1styear BIOLOGY Notes Chapter-8

Chapter-8
KINGDOM FUNGI 

KINGDOM FUNGI
“Fungi are a group of unicellular to multicellular, thalloid, heterotrophic, eukaryotic living organisms having a body called MYCELLIUM, made up of HYPHAE which are non-chlorophyllous & have cell wall (made up of chitin). Reproduction is usually A***UAL by means of spores”.

FUNGI ARE NEITHER COMPLETELY PLANTS NOR ANIMALS
Previously fungi were regarded as plants as they resemble the plants in many characteristics. But in addition fungi have many qualities just like the animals. So they are regarded in the midway between plants and animals.

PLANT LIKE CHARACTERISTICS OF FUNGI
Fungi resemble the plants in
• Having Cell Wall
• Lacking Centrioles
• Being non-motile

ANIMAL LIKE CHARACTERISTICS OF FUNGI
But Fungi also resemble with animals as they are
• Heterotrophic
• Lack cellulose in their cell wall
• Presence of chitin
It means that Fungi are neither completely plants nor animals.

CONFIRMATION
Detail studies also confirm that Fungi are different from all other organisms.

NUCLEAR MITOSIS
They have a characteristic mitosis called Nuclear-mitosis, during which nuclear membrane does not break & spindle is formed with in the nucleus.

SOME REPRESENTATIVES OF KINGDOM FUNGI
Some imp. Examples are as follows:-
• YEAST
• MUSHROOMS
• PENICILLIUM
• MOLD
• MUCOR
• RHIZOPUS

STRUCTURE OF BODY OF FUNGUS
MYCELIUM
The complete multicellular body of fungus is called MYCELIUM, which is composed of white fluffy mass of branched hyphae.

HYPHAE
A few of true fungi are unicellular (such as yeast) but most have multicellular body (mycelium) consisting of long, slender, branched, tubular, thread like filaments called as Hyphae which spread extensively over the surface of substrate.

HYPHAE
TYPES OF HYPHAE
Hyphae can be divided in to two types:
1. Septate or Multicellular Hyphae
2. Non-septate or multinuclear or coenocytic hyphae.

1.SEPTATE HYPHAE
DEFINITION
“Those hyphae which are separated by cross-walls called “septa” into individual cells containing one or more nuclei , are called “Septate Hyphae”
EXAMPLE: Mushrooms

2. NON-SEPTATE HYPHAE
DEFINITION
Those hyphae, which lack septa & are not divided into individual cells, instead these are in the form of long, multinucleated large cells are called Non-septate or Coenocytic Hyphae.
EXAMPLE: Mucor & Rhizopus

CELL WALL OF HYPHAE
CHITIN is the chief component present in the cell wall of most fungi, Because it is more resistant to decay than are the Cellulose & lignin which make up plant cell wall.

CYTOPLASM OF HYPHAE
In septate Hyphae ----- Cytoplasm flows through the pores of septa from cell to cell, carrying the materials to growing tips & enabling the hyphae to grow rapidly, under favorable conditions. In non-septate hyphae ------ cytoplasm moves effectively, distributing the materials throughout.

NUCLEI OF HYPHAE
All fungal nuclei are HAPLOID except for transient diploid zygote that forms during ***ual reproduction.

MAIN FUNCTION OF HYPHAE
Extensive spreading system of Hyphae provides enormous surface area for absorption.

NUTRITION IN FUNGI
ABSORPTIVE HETEROTROPHS
All fungi lack chlorophyll & are heterotrophs ( obtain carbon & energy from organic matter, They obtain their food by direct absorption from immediate environment & are thus “ABSORPTIVE HETEROTROPHS”.

DIFFERENT MODES OF HETEROTROPHIC NUTRITION IN FUNGI
Being Heterotrophic, fungi can exist as
1- Saprotrophs or saprobes ( Decomposers )
2- Parasites
3- Predators
4- Mutualists

1. SAPROBIC OR SAPROTROPHIC FUNGI ( DECOMPOSERS)
Saprobic fungi along with bacteria, are the major decomposers of biosphere, contributing to the recycling of the elements (C,N,P,O,H & etc) used by living things.

DEFINITION
“Those fungi which obtain their food (energy, carbon & nitrogen), directly by digesting the dead organic matter are called “SAPROBIC FUNGI” OR “DECOMPOSERS”

MECHANISM OF ABSORBING FOOD (DEVELOPMENT OF RHIZOIDS)
These fungi anchor to the substrate by modified hyphae, the RHIZOID, which provide enormous surface area for absorptive mode of nutrition.

SECRETION OF DIGESTIVE JUICES
Saprobic fungi secrete digestive juices, which digest organic matter & the organic molecules thus produced are absorbed, back into the fungus.

2. PARASITIC FUNGI
DEFINITION
Those fungi which absorb nutrients directly from living host cytoplasm are called PARASITIC FUNGI.

MECHANISM
For obtaining, their food requirements, these fungi develop specialized hyphal tips called as HAUSTORIA which penetrate the host tissues for absorbing nutrients.

TYPES OR PARASITIC FUNGI
Parasitic fungi may be of two types

A. OBLIGATE PARASITES
B. FACULTATIVE PARASITES.

(A) OBLIGATE PARASITES
DEFINITION
Those parasitic fungi which can grow only in their living host & cannot be grown on available defined growth culture medium, are called “ Obligate Parasites”.
EXAMPLES
• Many mildews
• Most of Rust species.

(B) FACULTATIVE PARASITES
DEFINITION
“Those parasitic fungi which can grow parasitically on their host as well as by themselves on artificial growth media, are called “ Facultative Parasites”.

3. PREDATORY FUNGI
DEFINITION
“Those fungi which obtain their food by killing other living organisms are called PREDATORY FUNGUS
EXAMPLES
1. Oyster Mushrooms ( Pleurotus astreatus ).
2. Some species of Arthrobotrys.

MECHANISM OF OBTAINING FOOD
1. IN OYSTER MUSHROOMS
Oyster mushroom is a carnivorous fungus. It Paralyses the nematodes (that feed on this fungus), penetrate them & absorb their nutritional contents, primarily to fulfill nitrogen requirements. It fulfill it glucose requirements by breaking the woods.

2. IN ARTHROBOTRYS
• Constrictor ring development
Some species of Arthrobotrys trap soil nemotodes by forming CONSTRICTING RING, their hyphae invading & digesting the unlucky victim.

4. MUTUALISTIC FUNGI
DEFINITION
“Those fungi which form such symbiotic associations with other living organisms in which both partners of association get benefit from each other are called MUTUALISTIC FUNGI & Such association are called as “MUTUALISTIC SYMBIOTIC ASSOCIATIONS”

TWO MUTUALISTIC SYMBIOTIC ASSOCIATIONS FORMED BY FUNGI
Fungi form two key mutualistic symbiotic associations. These are:
1. LICHENS
2.MYCORRHIZAE

1. LICHENS
SYMBIOTIC PARTNERS IN LICHENS
Lichens are mutualistc & have symbiotic associations b/w certain fungi (mostly Ascomycetes) & imperfect fungi & few Basidiomycetes (about 20 out of 15000 species of lichens) & certain photoautotroph either green algae or cynobacterium or sometimes both.

MUTUAL BENEFIT
In lichens, fungi protect the algal partner from strong light & desiccation & itself gets food through the courtesy of alga.

AREAS WHERE LICHENS GROW
Lichens can grow at such places such as bare rocks & etc, where neither of the components alone can grow.

ECOLOGICAL IMPORTANCE OF LICHENS
From ecological point of view, lichens are very important because they serve as BIO INDICATORS of AIR POLLUTION.

2. MYCORRHIZAE
SYMBIOTIC PARTNERS
Mycorrhizae are mutualistic association b/w certain fungi & roots of vascular plants (about 95% of all kinds of vascular plants).

MUTUAL BENEFIT
The fungal hyphae dramatically increase the amount of soil contact & total surface area for absorption & help in direct absorption of nutrients from soil. The plant on the other hand, supplies organic carbon to fungal hyphae.

TYPES OF MYCORRHIZAE
There are two main types of mycorrhizae.
1. Endomycorrhizae
2. Ectomycorrhizae

1. ENDOMYCORRHIZAE
In Endomycorrhizae, the fungal hyphae penetrate the outer cells of plant root, forming coils, swellings & minute branches, & also extend out into surrounding soil.

2.ECTOMYCORRHIZAE
In Ectomycorshizae the hyphae surround & extend between the cell but don’t penetrate the cell walls of roots.
EXAMPLE
Mutualistic association between fungi & pines & firs

REPRODUCTION IN FUNGI
Two kinds of reproduction are usually found in Fungi
1. A***UAL REPRODUCTION
2. ***UAL REPRODUCTION
Except In perfect Fungi in which ***ual reproduction has not been observed.

1. A***UAL REPRODUCTION
DEFINITIION
The most common means of reproduction in fungi which does not involve ***es, reduction division & fertilization is called A ***UAL REPRODUCTION

DIFFERENT MODES OF A***UAL REPRODUCTION
In fungi , a***ual reproduction take place by following ways:
1- SPORE FORMATION
2- CONIDIA FORMATION
3- FRAGMENTATION
4- BUDDING.

1- SPORE FORMATION
INTRODUCTION
It is the most common type of a***ual reproduction in fungi in which large no of spores are developed with in the sporangia. Each spore on generation produces another mycelium.

EXPLANATION OF THE PROCESS
SPORES
Spores may be produced by ***ual or a***ual process, are haploid, thick walled, non-motile & not needing water for their dispersal, They are very small & produced in very large no. with in the SPORANGIUM.

SPORANGIUM
Spores are produced inside the reproductive structures called SPORANGIA, which develop as swellings at the tips of SPORANGIOPHORES.

SEPARATION OF SPORANGIUM FROM HYPHAE
After the formation of spores, sporangium becomes separated from hypae by a complete septa.

BREAKAGE OF SPORANGIAL WALL
On maturity of the spores, the outer wall of sporangium breaks down & spores are dispersed.

DISPERSION OF SPORES
Spores are usually dispersed by air currents to great distances & cause wide distribution of many kinds of fungi. They may also be dispersed by small animals & insects & by rain splashes.

GERMINATION OF SPORES
In a favorable condition, on a proper substrate, the spore germinates giving rise to new fungal hyphae.
EXAMPLE

2.CONIDIA FORMATION
INTRODUCTION
The type of a***ual reproduction in fungi in which large number of a***ual spores called “CONIDIA are formed, each on germination giving rise to new mycelium is known as CONIDIAL REPRODUCTION.

EXPLANATION
CONIDIA
Conidia are non-motile, a***ual spores which may be produced in very large number & can survive for weeks, causing rapid colonization on new food.

CONIDIOPHORES
Conidia are not developed inside the sporangium but they are usually cut off at the end of modified hyphae called CONIDIOPHORES, commonly in chains or clusters.
EXAMPLE
A***ual reproduction by conidia formation is very common in ASCOMYCETES.

3.FRAGMENTATION
It is the type of a***ual reproduction in which mycelium of some fungal hyphae breaks into pieces or fragments. Each fragment develops into a new mycelium.

4. BUDDING
INTRODUCTION
Budding is an asymmetric a***ual division in which tiny outgrowth or bud is produced which may separate & grow by simple relatively equal cell division into new mycelium.
EXAMPLE
Unicellular yeasts reproduce by budding

***UAL REPRODUCTION
INTRODUCTION
Details of ***ual reproduction very in different groups of fungi on the basis of which fungi can be divided into four major phyla, However the fusion of haploid nuclei & meiosis are common to all.
EXPLANATION
***ual reproduction in fungi takes place through several stages, which are as follows.

PLASMOGAMY
When fungi reproduce ***ually, hyphae of two genetically different but compatible mating types come together & their cytoplasm fuse. This process is called PLASMOGAMY, This step is common in all types of fungi.

IN ZYGOMYCOTA
In Zygomycota after Plasmogamy following steps occur.

KARYOGAMY
In zygomycetes, Plasmogamy is followed by fusion of nuclei, called as KARYOGAMY

ZYGOT FOMATION & MEIOSIS
In ZYGOMYCETES, fusion of nuclei, leads directly to the formation of zygot, which divides by meiosis when it germinates.

IN ASCOMYCOTA AND BASIDIOMYCOTA
In these groups of fungi, following steps after plasmogamy.

FORMATION OF DIKARYOTIC NYPHAE
In these groups, the two genetic types of haploid nuclei from two individuals my coexist & divide in the same hyphae for most of the life of fungus. Such as fungal hyphae is called DIKARYOTIC OR HETEROKARYOTIC HYPHA/CELL.

FORMATION OF FRUITING BODIES
Extensive growth of dikaryotic hyphae may lead to the formation of massive structures of interwoven hyphae called as Fruiting Bodies, such as
• Basidia/ Basidiocarps
• Asci/ Ascocarps

SYNGAMY & MEIOSIS
Fusion of two haploid nuclei occurs with in the fruiting bodies forming a zygote, This is called as SYNGAMY, followed immediately by meiosis.

FORMATION OF HAPLOID ***UAL SPORES
Each zygote divides immediately by meiosis to form four haploid spores, which when release are dispersed, some of them giving rise to new hyphae.

CLASSIFICATION OF FUNGI
There are four major divisions of fungi, which are divided on the basis of their ***ual reproduction.
1- ZYGOMYCOTA
2- ASCOMYCOTA
3- BASIDIOMYCOTA
4- DEUTEROMYCOTA

1- ZYGOMYCOTA
INTRODUCTION
Zygomycota are by far the smallest of four groups of fungi, with only about 600 named species. This group includes more frequently bread molds as well as a variety of other microscopic fungi found on decaying organic material.

CHARACTERISTIC FEATURE
The group is named after a characteristic feature of the life cycle of its member, the production of temporalily dormant structures called ZYGOSPORES.
The zygomycetes lack septa in their hyphae i.e coenocytic hyphae, except when they form sporangia or gametangia.

LIFE CYCLE OF ZYGOMYCOTA
In the life cycle of zygomycota, two types of reproduction occurs:
A- ***UAL REPRODUCTION IN ZYGOMYCOTA
B- A***UAL REPRODUCTION IN ZYGOMYCOTA

(A) ***UAL REPRODUCTION IN ZYGOMYCOTA
***ual reproduction takes place by fusion of GAMETANGIA in following steps:

FORMATION OF PROGAMETANGIUM
When two hyphae came in contact with each other, each of them gives a lateral progametangium, facing each other.

DIFFERENTIATION OF PROGAMETANGIA INTO GAMETANGIA & SUSPENSORS
Later on, each of the progametangium differentiates into two parts
• Apical swollen part called GAMETANGIUM, containing numerous nuclei
• Basal hollow part called SUSPENSOR.

GAMETANGIAL COPULATION
The gametangia may be formed on hyphae of different mating types or on a single hyphae. If different mating types are involved, fusion between pairs of haploid nuclei occurs immediately.

ZYGOT FORMATION
Fusion of haploid nuclei results in formation of diploid zygote nuclei, Except for the zygote nuclei, all nuclei of zygomycota are haploid.

ZYGOSPORE FORMATION
After the formation of diploid zygote nuclei, the fused portion of hyphae develops into ZYGOSPORES.

GERMINATION OF ZYGOSPORE
Under favorable condition zygospore germinates & giving rise to new mycelium. Meiosis occurs during germination.

(B) A***UAL REPRODUCTION IN ZYGOMYCOTA (BY SPORE FORMATION )
A***ual reproduction occurs much more frequently than ***ual reproduction in the zygomycetes.
EXPLANATION
As previously discussed in spore formation

EXAMPLES OF ZYGOMYCETES
1- MUCOR
2- RHIZOPUS STOLONIPER

2-ASCOMYCOTA
INTRODUCTION
The second division of fungi, the ASCOMYCOTA is a very large group of about 30,000 named species with many more being discovered each year.

CHARACTERISTIC FEATURE
The ascomycota are named for their characteristic reproductive structure, the microscopic, club shaped ASCUS.

TYPE OF HYPHAE
The hyphae of ascomycetes are divided by septa i.e septate hyphae, but the septa are perforated & the cytoplasm flows along the length of each hyphae. The septa that cut off the asci & conidia are initially perforated like all other septa, but later they often become blocked.

LIFE CYCLE OF ASCOMYCOTA
In life cycle of ascomycota, Both ***ual & a***ual reproduction occurs.

(A) ***UAL REPRODUCTION IN ASCOMYCOTA
***ual reproduction occurs through following steps.

1- FORMATION OF MALE GAMETANGIUM OR ANTHERIDIUM
The hyphae of ascomycetes may be either homokaryotic & heterokaryotic. The cells of these hyphae usually contain from several to many nuclei. These cells form Antheridium or male gametangium.

2- FEMALE GAMETANGIUM OR ASCOGONIUM
The gametangium which develop beak like out growth called as TRICHOGYNE, is called female gametangium or Ascogonium.

3- FUSION OF MALE & FEMALE GAMETANGIUM
When antheridium is formed , it fuses with trichogyne of an adjacent ascogonium. Fusion of cytoplasm or plasmogamy occurs.

4- PAIRING OF NUCLEI
After plasmogamy, nuclei from antheridium then migrate through the trichogyne into the ascogonium, & pair with nuclei of opposite mating types.

5- FORMATION OF DIKARYOTIC HYPHAE & DIKARYOTICY
Dikarytic hyphae then arise from the area of fusion. Throughout such hyphae, nuclei that represent the two different original mating types occur ( DIKARYOTICY ) Such hyphae are also called as HETEROKARYOTIC HYPHAE.

6- FORMATION OF ASCOCARPS OR FRUITING BODIES
Excessive growth of monokaryotic or dikaryotic hyphae results in formation of massive structures of tightly interwoven hyphae, called as FRUITING BODIES OF ASCOCARPS, which corresponds to the visible portions of a morel or cup fungus.

7- ASCI FORMATION
Asci are special reproductive structures which are formed on special fertile layers of dikaryotic hyphae with in the Ascocarps.

8- SEPARATION OF ASCI
-+The asci are cut off by the formation of septa at the tips of heterokaryotic hyphae.

9- SYNGAMY
There are two haploid nuclei with in each ascus one of each of which belongs to different mating type. Fusion of these two nuclei occurs within each ascus called as SYNGAMY.

10- ZYGOT FORMATION
Syngamy results in zygote formation, which divides immediately by meiosis, forming four haploid daughter cells.

11- FORMATION OF ASCOSPORES
Four haploid daughter nuclei, usually divide again by mitosis , producing 8 haploid nuclei that become walled & called ASCOSPORES.

12-BURSTING OF ASCUS
In most Ascomycetes, the ascus becomes highly turgid at maturity and ultimately bursts, often at a perforated area, which may be pore or slit or lid

13- DESPERSION & GERMINATION OF ASCOSPORES
After bursting, the ascospores may be thrown as far as 30 cm. Under favorable circumstances they germinate giving new hyphae.

TYPES OF ASCOCARPS IN ASCOMYCETES
According to their shape, Ascocarps are of following three types:

1- OPOTHECIUM
The ascocarps of cup fungi & the morels are open, with the asci lining the open cups called OPOTHECIUM.

2- CLEISTOTHECIUM
Some ascocarps are closed & called as ‘CLESTOTHECIUM’

3- PERITHECIUM
Some ascocarps have small opening at the apex called as PERITHECIUM. Ascocarps of NEUROSPORA are of this type.

(B) A***UAL REPRODUCTION IN ASCOMYCOTA (BY CONDIA FORMATION)
INTRODUCTION
The type of a***ual reproduction in fungi in which large number of a***ual spores called “CONIDIA are formed, each on germination giving rise to new mycelium is known as CONIDIAL REPRODUCTION.

EXPLANATION
CONIDIA
Conidia are non-motile, a***ual spores which may be produced in very large number & can survive for weeks, causing rapid colonization on new food.

CONIDIOPHORES
Conidia are not developed inside the sporangium but they are usually cut off at the end of modified hyphae called CONIDIOPHORES, commonly in chains or clusters.

EXAMPLE
A***ual reproduction by conidia formation is very common in ASCOMYCETES.

3.BASIDIOMYCOTA
INTRODUCTION
The basidiomycetes, third division of fungi have about 16,000 named species. More is known about some members of this group than about any other fungi.

CHARACTERISTIC FEATURE
Basidiomycetes are named for their characteristic ***ual reproductive structures, the BASIDIUM, which is club shaped like as ascus.

LIFE CYCLE OF BASIDIOMYCOTA
In life cycle of Basidiomycota, reproduction is usually ***ual. A***ual reproduction is not very important.

(A) ***UAL REPRODUCTION IN BASIDIOMYCOTA
The life cycle of basidiomycetes begin with the production of hyphae which may be of two types.
1- Homokaryotic hyphae giving rise to primary mycelium.
2- Heterokaryotic hyphae giving rise to secondary mycelium.

PRIMARY OR MONOKARYOTIC MYCELIUM
Homokaryotic or monokaryotic hyphae lack septa at first. Eventually, However, septa are formed between nuclei of these hyphae. A basidiomycete mycelium made up of monokaryotic hyphae is called PRIMARY MYCELIUM.

SECONDARY OR DIKARYOTIC MYCELIUM
Mycelium of basidiomycetes, with two nuclei, representing the two different mating types b/w each pair of septa, is called SECONDARY OR DIKARYOTIC MYCELIUM. Most of the mycelium of basidiomycetes that occur in nature is dikaryotic & often only dikaryotic mycelium is able to form basidiocarps.

FORMATION OF BASIDIOCARP OR FRUITING BODY 
Dikaryotic mycelium is responsible for the formation of FRUITING BODY in Basidiomycetes called as BASIDIOCARP, made up of tightly interwoven dikaryotic hyphae.

FORMATION OF BASIDIUM
Basidium is characteristic reproductive structure of Basidiomycetes, which is club shaped & formed with in the Basidiocarp. This produces slender projection at the end called as STERIGMATA, in this way.

SYNGAMY & ZYGOT FORMATION
Nuclear fusion or syangamy occurs in Basidium, giving rise to diploid zygote, the only diploid cell of the life cycle.

MEIOSIS & BASIDIOSPORE FORMATION
Meiosis occurs immediately after the formation of zygot, resulting in the formation of four haploid nuclei, which are incorporated in Basidiospores. In most member of this division basidiospores are borne at the sterignata

DISPERSION AND GERMINATION
Same as in Ascomycetes

(B) A***UAL REPRODUCTION IN IN BASIDIOMYCOTA
In contrast to their effective ***ual reproduction, a***ual reproduction is rare in most basidiomycetes.
EXAMPLES OF BASIDIOMYCETES
• MUSHROOMS
• TOAD STOOLS
• PUFF BALLS
• JELLY FUNGI
• SHELF FUNGI
• PLANT PATHOGENS CALLED RUSTS & SMUTS,

4.DEUTEROMYCOTA (FUGI IMPERFECTI)
INTRODUCTION
“The fungi that are classified is this group, are simply those in which the ***ual reproductive stages have not been observed. In other words, most of the Fungi Imperfecti are as ascomycota that have lost the ability to reproduce ***ually. There are some 17000 described species of this group.”

CHARACTERISTIC FEATURE
***ual reproduction is absent among Fungi Imperfecti

LIFE CYCLE OF DEUTEROMYCOTA
Although in life cycle of deuteromycetes or Fungi Imperfecti, true ***ual reproduction is absent, but there is certain type of GENETIC RECOMBINATION which seems to be responsible for some of the production of new pathogenic strains of wheat rust.

GENETIC RECOMBINATION IN FUNGI IMPERFECTI PARA***UALITY
In para***uality, exchange of portions of chromosomes between the genetically distinct nuclei with in a common hyphae takes place. This is the special type of genetic recombination occurs in fungi Imperfecti.
EXAMPLES OF FUNGI IMPERFECTI
Among the economically important genera of Fungi Imperfecti are
1- PENICILLIUM
2- ASPERGILLUS
3- Most of the fungi that cause skin diseases in humans, including athlete’s foot & ring worm are also fungi imperfecti.

ECONOMIC IMPORTANCE OF FUNGI
Fungi play a vast role in economic field they show both harmful & useful activities to human beings.

USEFUL FUNGI
Following are some of the beneficial effects of fungi.

FOOD
Many kinds of edible fungi are in the form of mushrooms, are a source of nourishing & delicious food dishes. But not all the mushrooms are edible. Some of them are poisonous & called as toad stools or death stool. Yeast, another kind of fungi, are utilized in baking industry.

MEDICINES
Nearly two dozens antibiotics have been isolated from different types of fungi & bacteria, like
• Penicilliun from penecillium notatum
• Neomycin
• Chloromycetin
• Tetramycin & etc.

FOOD PRODUCTION
Many kinds of Yeast are used in the production of bakery & brewery products. Some species of genus PENICILLIUM give characteristic flavors & aromas to the cheese.

FERMENTATION
Species of Aspergillus, are used for fermenting soya sauce & soya paste. Citric Acid is produced commercially with members of this genus under highly acidic condition.

SOIL FERTILITY
Fungi maintain the soil fertility by decomposing the dead organic matter e.g Mycorhizal fungi.

PRODUCTION OF ORGANIC COMPOUNDS
May species of fungi are used in the production of organic compound such as vitamins, proteins & fats. Saccharomyces, synthesizes a range of vitamin B group.

HARMFUL FUNGI
Following are some of the harmful effects of fungi,

FOOD SPOILAGE
Saprophytic fungi cause tremendous amounts of spoilage of food stuff. 15-20% of worlds fruit is lost each year due to fungal attack.

SPOILAGE OF WOOD & LEATHER ARTICLES
Many fungi spoil leather goods, woods, wool, books, timber, cotton & etc. WOOD-ROTTING FUNGI destroy not only living trees but also structural timber. BRACKET/SHELF FUNGI cause lot of damage to store cut lumber as well as stands of timber of living trees.

TOXINS
Many fungi are poisonous . AMANITA VERNA is a mushroom, which produces deadly poisonous substance known as AMANITIN, which causes serious problems in respiratory system & blood circulatory system.

FOOD POISONING
Some fungi during decomposing food release certain poisonous substances collectively known as MYCOTOXINS. Mycotoxins are the major source of food poisoning.

DISEASES
Fungi cause a number of diseases in plants as well as in human beings.

PLANT DISEASES CAUSED BY FUNGI
Fungi destroy many agricultural crops, fruits, ornamentals & other kinds of plants because they produce several enzymes that can breakdown cellulose, Lignin and even cutin. Following are some of the serious plant disease caused by Fungi.

RUST & SMUT DISEASES
Rust & smut diseases are serious diseases of WHEAT, RICE, CORN &other cerial crops. They cause extensive damage.

POTATO BLIGHT
A serious disease of potato caused by a fungus known as PHYTOPTHORA INFESTANS. Other plant disease are.
• Powdery mildews ( on grapes, rose, wheat & etc).
• Ergot of rye
• Red rot of sugar cane
• Potato will
• Cotton root rot
• Apple scab
• Brown rot of peaches, plums, apricots & cherries.

ANIMAL DISEASES CAUSED BY FUNGI
Following are some of the fungal diseases in man.

SKIN DISEASES
RING WORM & ATHELETE’S FOOT are superficial fungal infection caused by certain Fungi Inperfecti

ORAL THRUSH
CANIDIA ALBICANS, a yeast causes oral & Vaginal thrush.

ASPERGILLOSIS
Aspergillosis is the disease of ear & lungs caused by ASPERGILLUS. It occurs only in person with defective immune system such as AIDS & cause death.

CANCER
Some strains of ASPERGILLUS FLAVUS produce one of the most carcinogenic ( cancer causing ) mycotoxins called AFLATOXINS.

ERGOTISM
Ergotism is caused by eating bread made from PUROLE ERGOT- Contaminated flour. The poisonous material in the ergot causes nervous spasm, convulsions, psychotic delusion & even gangrene.

HISTOPLASMOSIS
Histoplasmosis is a serious disease of lungs caused by inhaling spores of a fungus, which is common in soil contaminated with bird’s feces.

1styear BIOLOGY Notes Chapter-7

Chapter-7
THE KINGDOM PROTOCTISTA (PROTISTS)

PLANT LIKE PROTOCTIST
ULVA: (SEA-LETTUCE)

OCCURANCE
• Ulva, commonly called Sea Lettuce, is a marine green alga.
• It is found attached to rocks, along the sea coast in intertidal zones (the area between the high tide and low tide mark)
• In Karachi, it is found on Manora coast.

STRUCTURE
• Ulva exhibits primitive simple multicellular organization.
• The plant body is a thallus, which is flat, erect , wrinkled and sheet like structure having a length of about 30 cm (1ft).
• The thallus is very thin and internally it is composed of two vertical rows of cells only.
• Its lower part forms a “hold fast”, consisting of long thread like cells for attachment to the substratum.

REPRODUCTION
Ulva can reproduce ***ually as well as a***ually.

(1)***UAL REPRODUCTION
• ***ual reproduction is isogamous and takes place in ***ual plants or gametophyte, which are haploid (n).
• Each cell of the gametophyte produces many biflagellate gametes, which are released in seawater.
• The gametes are morphologically similar or isogametes but the fusion takes place between gametes produce by two different gametophyte plants, which are termed as positive strain and the negative strain.
• Thus, ulva plant exhibits heterothallism (two type of plant body i.e. gametophyte (n) and sporophyte (2n) ulva).
• After fusion a diploid quadri flagellate zygote is formed.
• Zygote swims for some time then loses its flagella, secretes a wall around itself and undergoes a period of rest.
• Finally the zygote germinates and develops into a new diploid ulva plant, which is called a***ual plant or sporophyte.

(2)A***UAL REPRODUCTION
• A***ual reproduction takes place by formation of quadri flagellate zoospores in diploid a***ual plant or sporophyte, which is morphologically similar to gametophyte.
• Each cell (except the basal cells) of the sporophyte (2n) undergoes meioses or reduction division and forms 8-16 zoospores, which are released in water.
• After swimming they lose flagella and undergo a period of rest.
• Each zoospore ultimately developes and forms haploid ***ual plant i.e. gametophyte, thus completing the life cycle.

ALTERNATION OF GENERATION
A distinct regular alternation of generations between the haploid gametophytes (***ual plant) and diploid sporophyte (a***ual plant) is present. Since the two plants are morphologically similar so this process is known as “Alternation of generation (isomorphic)”

CHLORELLA

OCCURANCE
• Chlorella is a fresh water alga found floating in stagnant water of ponds, pools and ditches.
• It is easily cultured and has been used an experimental organism in research in photosynthesis.

STRUCTURE
• The body of chlorella is one celled, spherical in outline and solitary.
• It contains a single nucleus and a cup-shaped chloroplast usually with out pyrenoid.

REPRODUCTION (A***UAL REPRODUCTION)
• Reproduction takes place by aplanospore formation, which involves the division of protoplast into 8-16 daughter protoplast.
• Each daughter protoplast secrets a wall to produce a non-motile aplanospore.
• On release from the parent cell, each aplanospore forms a new vegetative cell.

IMPORTANCE
Recently an antibiotic known as “Chlorellin” useful for the control of bacterial diseases has been prepared from the plant.

FUNGI LIKE PROTOCTIST
SLIME MOLD (PLASMODIUM STAGE)
• In initial stages of life cycle, slime mold are creeping masses of living substances, having the consistency of an unboiled egg white and the colour of the yolk.
• It sends out protoplasmic arms that engulf and digest bacteria from the surface of rotten rock or leaves.
• This amoeboid stage of slime mold is called plasmodium stage.
• The plasmodium consists of the cytoplasm in which are embedded many nuclei, food vacuoles and undigested food particles.
• Plasmodia can move along the forest floor, on to dead leaves that are bathed in sunlight.

FRUITING BODY
• In dry warm environment metamorphosis in Plasmodia takes place and it changes into cluster of fruiting bodies.
• Depending on the species the fruiting bodies look like golf balls, feathers, bird cages or worm like and in a great variety of colours.

REPRODUCTION
• Each fruiting body produces a large number of microscopic a***ual reproductive cells known as spores.
• Each spore has a single nucleus and a thick protective wall.
• Germination of the spore occurs when there is plenty of water and suitable temperature.
• When a slime mold’s spore germinates, it produces one or more tiny cells.
• Each cell has a pair of flagella that propel it through the film of water, which is necessary for its germination.
• These flagellated cells some times function as gametes (*** cells) and fuse in pairs. This is true ***ual reproduction.
• Fusion of the gametes forms zygote, which become amoeboid and form a new plasmodium i.e. multinucleated slime mold

PHYTOPTHORA INFESTANS(WATER MOLD)
• This fungi like protoctist belongs to family Oomycotes.
• It is a pathogenic organism causing. “late blight of potato”

STRUCTURE
• The mycellium consist of Hyphae which are endophytic, branched, aseptate coenocytic, hyaline and nodulated.
• The rounded or branched hustoria are found which absorb food material from the host cells.

REPRODUCTION
***ual as well as a***ual reproductions are present.

(A)A***UAL REPRODUCTION
• A***ual reproduction takes place by means of biflagellate zoospores produce inside the productive structure Sporangia.
• The spores are produced on the branched Sporangiophore in favorable condition.
• Sporangiophore coming out through the stomata, in groups on the lower surface of infected leaves.
• The sporangia are produced on the branches of sporangiophore.
• On maturation, the sporangia the detached from sporangiophore.
• On maturation the protoplasm of the sporangium converts into uninucleate, vacuolated and naked zoospores.
• When mature sporangium burst the zoospores liberate in the film.

(B)***UAL REPRODUCTION
• ***ual reproduction is zoogamous.
• The female *** organ is oogonium. while the male *** organ is antheridium.
• The antherialium develops first and the oosgonium later.
• Both *** organ may develop on he same Hyphae or on two adjacent Hyphae lying side by side.
• The oogonium hyphae penetrates the antheridium.
• The oogonium is pear shaped and contains a single female nucleus in it.
• The fertilization takes place when the male and the female nuclei fuse in the egg after penetration of the oogonium in the antheridium.
• There is no fertilization tube and after fertilization the thick walled zoospore developed, which is present inside the oogonium.
• The oospore germinates in favorable conditions and produce new mycellium.
• Reduction division occurs during germinates of oospore.

ECONOMIC IMPORTANCE
• The Water Mold causes a disease in potato crop known as “late blight of potato”
• This disease effects both aerial and underground parts and whole plant becomes blighted in severe conditions.
• The disease appears in the form of brown spread patches on leaves and rapidly increases to the whole leaf surface.
• The tuber converts into a rotten pulpy mass emitting foul smell and remains small in size.
• A great danger to potato crop and causes sufficient damage of Potato crop.


EUGLENA
Euglena is an unicellular, flagellated organism. It belongs to the division “Euglenophyta”

OCCURANCE
Euglena commonly found in drains, ponds and is also present in soil, blackish water and even salt water.

DUEL NATURE
• Euglena has characteristics of both animals and plants.
• It is more evolved than green Algae.

STRUCTURE
1. It is somewhat elongated animal, almost pointed at both ends.
2. It has definite and easily stainable nucleus.
3. It has well defined chloroplast as in higher plants.
4. All the Euglena have two flagella usually one of them is long and the other one short by which they can swim activity.
5. They lack the outer cellulose cell wall, instead the protoplasm is bounded by a grooved layer called the “Pellicle”.
6. Euglena has a gullet near the base of the flagella and an eyespot containing a pigment called “Astaxanthin”.
7. Reproduction is usually a***uality by simple division.

TAXONOMIC POSITION OF EUGLENA
• One of the examples of Eukaryotes is Euglena.
• Belongs to group kingdom Protactista.

PLANT LIKE CHARACTERS IN EUGLENA
1. Presence of Chloroplast.
2. Undergoes physiological, biochemical process of photosynthesis.
3. Behaves as natural autotroph in presence of sunlight.

ANIMAL LIKE CHARACTERS IN EUGLENA
1. Absence of a cell wall.
2. Presence of a mouth with cytopharynx.
3. Eyespot containing animals pigment called “Astaxanthin”.
4. Presence of reservoir.
5. Can easily be converted into heterotopy after the loss of chloroplast.

ANIMAL LIKE PROTOCTISTA
PHYLUM PROTOZOA
GENERAL CHARACTERS
1. Protozoa are microscopic, unicellular (as single cell performs all vital activities) organisms.
2. These organisms are asymmetrical.
3. The body of organism may be naked or covered by pellicle to maintain the shape.
4. Cytoplasm of protozoans is usually divided into outer, ectoplasm and inner granular endoplasm.
5. Cell may be uninucleate or multinucleate. Nuclei are covered by nuclear membrane.
6. Protozoan may be solitary or colonial.
7. They are aquatic and are found in both fresh and marine water.
8. Nutrition may be holozoic (animal like), halophytic (plant like) or saprozoic (subsisting in dead organic matter) or parasitic.
9. Digestion is intracellular and is accomplished inside the food vacuole.
10. Locomotion takes place by flagella, cilia or psendopodia.
11. Respiration takes place through general body surface.
12. One or more contractile vacuoles are present for osmo-regulation.
13. Reproduction takes place by both a***ual and ***ual methods.
14. The a***ual methods include binary fission, multiple fission and budding.
15. ***ual reproductive methods include gamete formation (Isogamies and Anisogamous) or by conjugation.

CLASSIFICATION
About 30,000 species of protozoa are divided into five classes, which differ in their means of locomotion. 1. Class flagellate (Mastigophora).
2. Class sarcodina (Rhizopoda).
3. Class ciliate (Ciliophora).
4. Class suctoria.
5. Class sporozaa.

(1)CLASS FLAGELLATA
1. Locomotary organs are long hair like “Flagella” with are one or two in number.
2. Body is enclosed in a thin covering of “Pellicle”.
3. A***ual reproduction takes place by longitudinal fission.
4. Class Flagella is divided into sub classes.

(A) SUB-CLASS PHYTOFLAGELLATA (PHYTOMASTIGMA)
• Contain chlorophyll and perform process of photosynthesis.
• Examples: Euglena and Volvax.

(B) SUB-CLASS ZOOFLAGELLATA (ZOOMASTIGMA)
• Does not contain chlorophyll and are heterotrophic.
• Examples: Trypanosome and Leis mania.
• Some flagellates are parasites. For example: Trypanosome is a blood parasite human and causes African sleeping sickness. Its carrier is “Tse Tse fly”.

(2)CLASS SARCODINA (RHIZOPODA)
1. Locomotion takes place by “Psendopodium”.
2. Body shape is not definite and keep on changing because the pellicle is absent. Some have external sheats or skeletons.
3. Nutrition is mostly holozoic, some are parasite. E.g. Entamoeba, histolytic can cause human dysentery.
4. Example:

i. Entamoeba histolytic is a parasite living in intestine of man. ii. Foraminifera is a group including shelled sarcodimians. E.g. Polystomella. iii. Heliozoa is a group including fresh water organisms having fine, stiff and ray like psendopodia e.g. Actinophrys.

(3)CLASS CILIATA
1. Locomotory organs are cilia which are short, thin, protoplasmic structure, covering the body surface.
2. Body shape is definite and maintained by pellicle.
3. Many ciliates have a groove or depression called “Gullet” into which food can be brought.
This class is divided into two sub-classes.

(i) SUB-CLASS PROTOCILIATA
• Cilia all of equal size and uniformly distributed.
• Cytosomes absent.
• Nuclei two to many but all of one type e.g. Opalina

(ii) SUB-CLASS ENCILIATE
• Cilia of different types and not uniformly distributed.
• Cytosomes usually present.
• Nuclei of two types types Micronucleus and Meganucleus e.g. Paramecium, Balantidium.

(4)CLASS SUCTORIA
1. They are closely related to ciliates, therefore both are includes in same sub-phylum i.e. sub phylum Ciliphora.
2. Young individual have cilia and swim about but the adults are sedentary and have stalks by which they are attached to the substrate.
3. Body bears a group of delicate cytoplasmic tentacles, some of which are pointed to pierce their prey, where as others are tripped with rounded adhesive, knobs to catch and hold the prey.
4. The tentacles secrete a toxic material which may paralyze the prey.
5. Suctorians have two nuclei i.e. meganucleus and micronucleus.
6. Reproduction is by a***ual budding. E.g. Acineta, Ephelota.

(5)CLASS SPOROZOA
1. All are parasites.
2. Lomotary organs are absent.
3. Body covered by a thick cuticle.
4. A***ual reproduction is by multiple fission or sporulation.
5. ***ual reproduction is isogamies or anisogamous.
6. Examples.

(i) Plasmodium is a human blood parasite enters the human blood when an infected female Anopheles mosquito bites humans. Plasmodium reproduces a***ually in man and ***ually in the body of mosquito.
(ii) Monocytis lives as a parasites in seminal vesicles of earthworm.


MALARIA
INTRODUCTION
“Malaria is an infectious disease marked by attacks of chills fever, sweating occurring at intervals that depends on the time required for the development of a new generation of parasites in the body”.

CAUSATIVE AGENT
Malaria is caused by a protozoan parasite of the genus PLASMODIUM. It was discovered by LAVERAN in 1878.

TRANSMITTING AGENT
Malaria is transmitted into the blood of man by the bite of an infected “FEMALE AND PHELES MOSQUITO”. It was discovered by KING in 1717.

SYMPTOMS OF MALARIA
The symptoms of malaria first appear after several days of infection in man. He time taken by parasite before it appears in the blood is called INCUBATION PERIOD.

SYMPTOMS DURING INCUBATION PERIOD
The symptoms that appears in incubation period:
• Nausea.
• Loss of appetite.
• Constipation.
• Insomnia.
• Headache.
• Muscular pain.
• Aches in joint develops.

USUAL SYMPTOMS OF MALARIA
• Onset of malarial fever
• Shauking chills
• Sweating
• Rise in body temp. (may be up 106°)

MALARIA – A BIOLOGICAL PROBLEM
Malaria has been one of the man’s most important biological problems. Millions of people have been killed only because of his disease. To solve this problem, various biological methods were applied to find out in details. Experiments were performed, observation and data were collected, and finally the complete life cycle of the malarial parasite was studied.

STUDYING MALARIA EXPERIMENTALLY
In the experimental study of malaria, several HYPOTHESIS were presented and deductions were made for each of them. Experiments were performed to test the deduction and observations are recorded. If the deductions are proved true, the hypothesis regarded as correct.

HYPOTHESIS (1)
A hypothesis was made about the malarial parasite plasmodium that: “Plasmodium is the cause of malaria”

DEDUCTION
To test the above hypothesis, the following deductions were made: “If the plasmodium is the cause of malaria, then the patients suffering from malaria should have malarial parasite in their blood”.

EXPERIMENT
Experiment were carried out by examining blood samples from malarial patients that showed positive result. To prove it further experiments were repeated whenever malaria accured.

RESULT
In this way the hypothesis that the “Plasmodium is the cause of malaria” was found to be true.

HYPOTHESIS (II)
It was noted that people living around the marshy places were usually have the attack of malaria. Thus the hypothesis was stated “Malaria is associated with marshes”

DEDUCTION
To test the statements, a deduction was made that “If marshes are eliminated”.

EXPERIMENT
On experimental basis, marshes were eliminated and as a result the role of infection of malaria was greatly much reduced.

RESULT
It was this proved that malaria is associated with marshes. Thus the hypothesis stands true. Thus, it is new understood that accurate methods are essential to understood biological problems.

LIFE – CYCLE OF MALARIAL PARASITE
DISCOVERY
Life cycle of plasmodium in ANOPHELES MOSQUITO was first discovered in 1898.

PHASES OF LIFE CYCLE
The life cycle of plasmodium is digenetic involving two phases is two hosts for completion.
1. A***UAL PHASE IN MAN (PRIMARY HOST)
2. ***UAL PHASE IN MOSQUITO (SECONDARY HOST)

A***UAL CYCLE IN MAN (SCHIZOGONY)
INTRODUCTION
The life cycle of plasmodium in mass is A***ual and is called SCHIZOGONY, because “SCHIZONTS” are produced.

PHASES OF SCHIZOGONY
According to Graham (1948), the life cycle of plasmodium can be divided into four phases;

1. PRE-ERYTHROCYTIC PHASE (LIVER SCHIZOGONY).
2. ERYTHROCYTIC PHASE.
3. POST-ERYTHROCYTIC PHASE.
4. GAMORONY OR GAMETOCYTIC PHASE.

EXPLANATION OF SCHIZOGONY
INFECTION
A healthy person acquires infection when a female Anopheles mosquito, containing infective stages (SPOROZOITES) of parasite is its salivary gland, bites him for ****ing his blood.

(1)PRE-ERYTHROCYTIC PHASE
Once with in the human blood, the sporozoites circulate in the blood for about half an hour.

INVASION OF LIVER
After circulation in the blood, the sporozoites get into liver to invade the hepatic cells.

SCHIZONT FORMATION
After penetrating the liver cells, each sporozoite grows for no. of days and becomes a SCHIZONT.

CRYPTOZOITE FORMATION
SCHIZONT divides to form a large number of uninucleate CRYPTOZOITES, which are liberated when the liver cell burst.

METACRYPTOZOITE FORMATION
The released cryptozoites invade the fresh liver cells and multiply producing enormous no. of metacryptozoites.

(2) ERYTHROCYTIC PHASE
TROPHOZOITE FORMATION
The metacryptozoites after escaping into the blood stream, invade the red blood corpuscles. Each become rounded and is called TROPHOZOITE.

SIGNET RING STAGE
When trophozoite grows in size, the nucleus is pushed to one side into the peripheral cytoplasm. It resembles a signet ring and is preferred to an SIGNET RING STAGE.

MEROZOITE FORMATION
The trophozoite ingesis a large amount of cytoplasm of the R.B.C. The blood H6 is broken down into its protein components, which is used by trophozoite develops into an active amoeboid trophozoite. After active feeding, it becomes rounded and grows in size and become and SCHIZONT. It now undergoes SCHIZOGONY and produces MEROZOITES.

RELEASE OF MEROZOITES IN BLOOD
With the rupture of RBC’S, the merozoites are liberated into the blood plasma. These invade fresh corpuscles to repeat the cycle. The time taken to complete one erythrocytic cycle depends upon the species of Rasnodium.

(3) POST-ERYTHROCYTIC PHASE
Some merozoites produced in erythrocytic phase reach the liver cells and undergo schizonic development. This is known as Post-Erythrocytic Phase.

(4) GAMOGONY
FORMATION OF GAMETOCYTES
When successful a***ual multiplication is achieved, the merozoites donot proceed further with the erythrocytic phase but, after entering the RBC, increase in size to form Gamocytes.

TYPES OF GAMETOCYTES
Gametocytes are of two types:
1. Male Microgamo Cycle
2. Female Macrogamo Cycle
The Gametocytes do not divide, but remain within the host blood until they are injected by the vendor, in which they continue their ***ual development.

***UAL CYCLE IN MOSQUITO
INTRODUCTION
***ual life cycle of Plasmodium is completed in the gut of Female Anopheles Mosquito resulting in infective Sporozoites. This cycle is completed in 12-23 days.

PHASES OF ***UAL CYCLE
This cycle comprises of following stages:
1. Gametogony
2. Syngamy or Fertilization
3. Sporogony

EXPLANATION OF ***UAL CYCLE
(1) GAMETOGONY=
Gametogony refers to the Formation of Gametes. The gamocytes are taken up along with the blood into the stomach of the mosquito and develop into gametes.

FEMALE MACROGAMETE
The female gamocytes soon become macrogamete, which is larger in size and ready to fertilize.

MALE MICROGAMETE
Each male gamocyte forms 6 to 8 sperms like microgametes by a process of Exflagellation.

(2) SYNGANY OR FERTILIZATION
ZYGOT FORMATION
Within the gut of mosquito the two gametes of opposite ***es fuse together to form a zygot. This process is called Syngamy.

OKINETE FORMATION
After fertilization zygot differentiates into motile worm-like ookinete.

OOCYST FORMATION
Ookinete penetrates the stomach wall to settle down just under the mid gut. Here after observing nutrients, it develops a cyst around it and becomes spherical. This encysted is called Oocyst.

(3) SPOROGONY
The oocyst then enters a phase of a***ual multiplication, the Sporogony.

SPOROBLAST FORMATION
In 6 to 7 days, the nucleus of oocyst divides into several nuclei and cytoplasm envelops each one of them and thus hundreds of oval shaped Sporoblasts are formed.

SPOROZOITE FORMATION
The sporoblast nucleus again divides and forms hundreds of filamentous, uninucleated Sporozoites. The cyst bursts and liberated sporozoites migrates to the Salivary Gland where they await to penetrate to a human host.

1styear BIOLOGY Notes Chapter-6

Chapter-6
KINGDOM MONERA

BACTERIA
DISCOVERY
Bacteria was discovered by A.V. Leuwenhoek in 1676.

STRUCTURE OF BACTERIA
Bacteria are smallest and simplest living organism measures from 0.2m to 2 micron in breadth and 2 to 10 micron in length. They are strictly unicellular but some species remain associated with each other after cell division and form colonies.
A generalized bacterial cell consists of following structures.

(1)FLAGELLA
They are extremely thin appendages, which originate from basal body, a structure in the cytoplasm beneath cell membrane. Flagella help in bacterial locomotion.

(2)PILLI
They are hollow, filamentous flagella like appendages, which help in conjugation but not in locomotion.

(3)CAPSULE
It is a protective sheath made up of polysaccharides and proteins. It provides greater pathogenicity and protects bacteria against phagocytosis.

(4) CELL WALL
Bacterial cell wall mostly made up of amino acids, sugar and chitin. It surrounds the cell membrane, determine shape and protects bacteria from osmotic lyses. Most bacteria have a unique macromolecule called Peptidoglycan in addition to it. Sugar molecules, teichoic acid, glyco proteins and lipo polysaccharide are also present.

(5)CELL MEMBRANE
• It is present inside the cell wall attached to it at few places containing many pores.
• It is made up of lipids and proteins.
• It acts as a respiratory structure.

(6)CYTOPLASM
Bacterial cytoplasm is granular containing many small vacuoles, glycogen particles and ribosomes.

(7)MESOSOMES
• These are the invaginations of the cell membrane into the cytoplasm.
• They are in the form of vesicles, tubules or lamella.
• They help in the DNA replication, cell division, respiration and export of enzyme.

(8)BACTERIAL HEREDITARY MATERIAL
• Bacterial hereditary material DNA is found as concentrated structures called Bacterial chromosomes or chromatin bodies. It is mostly scattered in the cytoplasm.
• A small fragment of extra chromosomal circular DNA, called Plasmid is also present.

CLASSIFICATION OF BACTERIA
ON THE BASIS OF SHAPE
On the basis of shape bacteria can be divided into four categories.

(1) COCCI
• These are spherical or rounded bacteria presents in the form of mono, diplo or streptococcus form.
• They are non-flagellated and cannot move from one place to another place.

(2) BACILLI
• Bacilli are rod shaped bacteria, can be present in the form of diplo or streplobacilli.
• They may be flagellated and can move from one place to another.

(3) SPIRILLA
• These are spiral or cork, screw shape bacteria also known as spirochetes.
• It includes chlamydia and rekettia.

(4)VIBRIO OR COMMA
• These are slightly curved bacteria like vibrio cholera.
• They may be flagellated and can move.

ON THE BASIS OF RESPIRATION
On the basis of respiration bacteria can be divided into two main types.
(1)AEROBES
Require oxygen for respiration.

(2)ANAEROBES
Respire with out oxygen
Sub-classes of this classification are as follow:

(A)FACULTATIVE BACTERIA
Respire with or without oxygen.

(B)MICRO AEROPHILIC BACTERIA
Require low concentration of oxygen for growth

(C)OBLIGATE ANAEROBES
These bacteria only survive in absence of oxygen.

(D)FACULTATIVE ANAEROBES
These bacteria use oxygen but can respire with out it .

(E)OBLIGATE AEROBES
These bacteria only survive in the presence of oxygen.

ON THE BASIS OF NUTRITION
Bacteria can be divided into four main types on the basis of nutrition. Which are as follow.

(1) SAPROTROPHIC BACTERIA
• These bacteria depend on the dead organic matter for their nutrition.
• They are mostly present in the humus of soil and posses large number of enzymes that convert complex substances of humus to simpler compounds.

(2) SYMBIOTIC BACTERIA
• These bacteria are found associated with other living organism.
• They obtain their food from the host without harming it. E.g. Rizobium redicicola (Symbionts in the root nodules of pea family plants).

(3) PARASITIC BACTERIA
• These bacteria grow inside the tissues of other living organism
• They obtain food at the expense of their host.
• These bacteria lack certain complex system of enzymes therefore they usually depend upon host cell. E.g. Pneumococcus, Mycobacterium tuberculosis, Salmonella typhi.

(4) AUTOTROPHIC BACTERIA
• These bacteria can sythesize organic compound from simple inorganic substances.
Autotrophic bacteria can be divided into photosynthetic or chemosynthetic.

(A) PHOTOSYNTHETIC
• These bacteria contain green pigment chlorophyll, which is known as bacterial chlorophyll, or chlorobium chlorophyll.
• These pigments are present in mesosomes (invagination of the cell membrane in the cytoplasm)
• These bacteria utilize H2S during photosynthesis instead of water and liberate sulphur instead of oxygen.
sunlight

(B) CHEMOSYNTHETIC
• These bacteria obtain their energy from oxidation of some inorganic substances like iron, hydrogen, nitrogen and sulphur compounds.

LOCOMOTION IN BACTERIA
• Some bacteria can move from one place to another with the help of a wipe like structure flagella.
• Flagella allow bacteria to disperse into new habitats, to migrate towards nutrients and to leave unfavorable environment.
• Flagellated bacteria show orientation towards various stimuli, a behavior called Taxis.
• Some bacteria are chemo tactic, phototectic or magnetotatic.

GROWTH IN BACTERIA
In favorable conditions bacteria can grow, very rapidly. There are some factors affecting growth of bacteria such as Temperature, nutrient availability, PH and ion concentration. Bacterial growth can be divided into four main phases, which are as follows

(1)LAG PHASE
It is inactive phase during which bacteria prepare them for division.

(2)LOG PHASE
In this phase bacteria grow and multiply very rapidly.

(3)STATIONARY PHASE
In this phase bacterial multiplication is equal to bacteria death rate.

(4)DECLINE/DEATH PHASE
In this phase death is more rapid then multiplication rate.

REPRODUCTION IN BACTERIA
Usually a***ual reproduction is present in bacteria which is as follow

FISSION
Fission is the fastest mode of bacterial a***ual reproduction (Binary Fission)
• It usually takes place in favorable conditions.
• Hereditary material DNA in the form of chromatin body replicates.
• After the replication of hereditary material a constriction appears in the middle of the cell, which later splits it into two parts.
• Newly form bacterial cells grow in size and form nature bacterial cells.
• The single fission takes place in 20-30 minutes.

ENDOSPORE FORMATION
• It is the method of bacterial survival under unfavorable conditions. Following are the main characters of this process.
• During this process, the whole protoplasmic content gets shrink into a small mass.
• A cyst is formed inside the parental wall around constricted protoplasm to form endospore.
• On the return of favorable conditions parental wall raptures due to decay and endospore is set free.
• In the end, this endospore enlarges to form a mature bacterial cell.

GENETIC RECOMBINATION IN BACTERIA
Genetic changes with the help of which bacteria adopt new characteristics (drugs resistance pathogenic ability) is known as Genetic recombination
Three types of genetic recombination are present in bacteria, which are given as follow.

1.CONJUGATION
Simple process of genetic recombination in which genetic material is transferred from one bacteria to another through a conjugating tube. Conjugation in bacteria was discovered by Joshua Lederburg and Edward L.Tatum in 1946

EXPERIMENT
J.laderberg and E.Tatum performed an interesting experiment in order to prove conjugation in bacteria. Following are the main steps of this experiment.

1. They selected a wild type bacteria (E-coli) and obtain (triple nutritional mutants) different from one another.
2. Wild-type was capable of synthesizing six substances symbolized as A, B, C, D, E and F.
3. Mutant type I was capable of synthesizing three substances symbolized as A, B and C but not D, E and F.
4. Mutant type II was capable of synthesizing three substances D,E and F but not A,B and C.
5. These mutant type I and II were grown together in the growth medium having all the six substances A, B, C, D, E and F.
6. After several hours, three types of bacteria were detected after nutritional test which were,

i. Both mutant I and mutant II types.
ii. Wild type bacteria synthesizing all the six substances.
iii. A new type of bacterial strain requiring all the six substances for growth.
In this experiment, appearance of wild type and one new type is an evidence that conjugation had taken place.

2. TRANSDUCTION
It is the mode of genetic recombination in which genetic material is transferred from one bacteria to another by a third party, which is usually bacteriophage.
This process was experimentally carried out by Lederberg and Zinder in 1952.

EXPERIMENT
1. In this experiment, a bacteriophage is made to attack a bacterium known as “donor” (D).
2. The injected DNA of bacteriophage multiply to form a large number of daughter phages.
3. The donor bacterium (D) gives some of its genetic material “D” to the multiplying particles.
4. The phages released from this donor bacterium contain the genetic material of phage plus a little piece of the donor genetic material “D”.
5. These new phages then made to attack a new bacterium known as “Recipient” (R).
6. These recipient bacterium is not destroyed like the donor in order to reproduce normally. In this way, genetic material of the donor bacterium is carried to the recipient bacterium by a bacteriophage and this process is known as Transduction.

3. TRANSFORMATION
In this process, genetic information transfers from one bacteria to another by producing a change it (undergo a change).
This type of genetic recombination was first proved by Fred Griffith in 1928.

EXPERIMENT
• Griffithi injected a small quantity of R-type bacteria and a large quantity of heat killed S-type bacteria into the same mouse.
• This treatment proved fatal as mouse surprisingly suffered from Pneumonia and died.
• The autopsy of the mouse revealed the presence of living S-type bacteria in the mouse in addition to R- type.
From this experiment Griffith concluded that,
• The live R-type bacteria had been transformed into live S-type bacteria due to transfer of some material from dead S-type, cells.
• Thus this transformation occurred due to genetic recombination in R-type bacteria.
In his experiment, he had been working on two strains of bacteria “Pnemococcus”. One strain is known as smooth type (Virulent and causes Pneumonia) while the second strain is known as (Rough type (Non-Virulent and does not cause pneumonia).

VACCINATION
DEFINITION
Inoculation of host with inactive or weaken pathogens or pathogenic products to stimulate protective immunity.
• In case of subsequent natural infection with the same pathogen the immune system easily recognized the invader and comfortably managed to overcome the pathogen.
• A vaccine can taken orally (Polio vaccine) or injected into the body (Tetanus Vaccine).

IMMUNIZATION
DEFINITION
It is a process of induction of specific immunity by injecting antigens, antibodies or immune cells.
• Immunity can be protective or curative in nature.
• It promotes increased immunity against specific diseases.

CYNOBACTERIA (BLUE GREEN ALGAE)
MAIN CHARACTERISTICS OF CYNOBACTERIA
• They are prokaryotic unicellular autotrophic organisms mostly occur in colony form.
• They posses double layered cell wall.
• The protoplasm differentiated into an outer colored region chromoplasm, which contain various pigments in which chlorophyll “a” and phycocyanin are more important.
• Inner colorless region of the protoplasm is known as centroplasm.
• They are mostly aquatic (fresh water)
• ***ual reproduction is absent.
• A***ual reproduction takes place by means of Harmogonia, zoospores, akinates and fragmentation.

NOSTOC
• Nostoc is a typical example of blue green algae.

STRUCTURE
• Nostoc is a filamentous prokaryotic algae in which filaments are intermixed in a glatinous mass-forming ball like structure known as coenobium.
• A single filament look like a chain of beads.
• Each filament is unbranched and has a single row of rounded or oval cells.
• Each cell has double layered wall, outer thick wall is made up of cellulose mixed up with pectic compounds. While inner thin layer is made up of cellulose only.
• The protoplasm is differentiated into an outer colored region (chromoplasm) and an inner colorless region (centroplasm).
• The chromoplasm various pigments like chlorophyll, axanthophylls, carotene, phycocyanin and phycoerythrin.
• Ribosome’s, pseudovacuoe and reserve food in the form of cynophyceae starch are present.
• Hereditary material is present in cytoplasm with out the nuclear membrane.
• In Nostoc filaments slightly larger, colorless cells with thick walled known as “Heterocyst” are present.The function o Heterocyst is nitrogen fixation, food storage and multiplication of filament during unfavorable conditions.

NUTRITION
• It is an autotroph and prepares its food in the presence of sunlight.
• It also capable of fixing atmospheric nitrogen and converts it into nitrates in order to prepare amino acids and proteins, this activity takes place in Heterocysts.

REPRODUCTION
• Only a***ual reproduction is present which takes place by following methods.

(1) HORMOGONIA
• A portion of the filaments between two heterocysts is known as Hormogonia.
• During favorable conditions, filaments break up at the junction of each Heterocyst.
• The end cells of each homogonous divide to form long filaments of Nostoc.

(2) AKINETES
• It is the method of survival during unfavorable conditions.
• These are non-motile spores, formed from certain vegetative cells.
• Each akinete contains an outer layer “exospore” and inner layer “endospores”.
• On the return of favorable conditions, each akinete germinates by rupturing exospore and formed independent filaments by simple cell division.

IMPORTANCE OF CYNOBACTERIA
• They release oxygen as a by-product during photosynthesis.
• Many are capable of fixing atmospheric nitrogen.
• They are first colonizers of moist soil.
• Nostoc anabena is used as nitrogen fertilizer in agriculture due to its nitrogen fixing ability.

MONERA
• Discovery of bacteria A.V.Leuventoek.
• Size of bacteria = 0.2-2 micron (breadth)
• = 2-10 micron (length).
• Cell wall of bacteria made up of peptidoglycan.
• Arch bacteria do not contain peptidoglycan.
• Bacterial replications, cell division, respiration, export of enzymes = By means of mesosomes (invaginations of cell membrane)
• Saprophytic bacteria form humus (important component of soil)
• Photosynthetic bacteria = use H2S in photosynthesis instead of water.
• Chlorobium chlorophyll or bacterial chlorophyll discovered by Von Nell 1930.

DIVERSITY OF LIFE
• Father of taxonomy = Charles Linneus.
• Genetics = final tool in classifying living organism.
• Basic unit of Biological classification = species.
• Five kingdom system of Robert Whittaker = 1969.
• Discovery of Virus = Iwanosky 1892.
• TMV Virus discover by Wendell Stanley in 1935.
• Size of Virus = 20nm-250nm.
• AIDS is caused by Human Immune Deficiency Virus (HIV)
• As a result of lytic cycle of bacterio phage 100-200 daughter phage viruses are produced.