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.

1styear BIOLOGY Notes Chapter-5

Chapter-5
VARIETY OF LIFE

BASIS OF CLASSIFICATION OF LIVING ORGANISMS
The living organisms are classified on the basis of Homology, comparative Biochemistry cytology and Genetics.
(a) Homology
(b) Cytology.
(c) Bio-chemistry.
(d) Genetics

(A) HOMOLOGY
The organisms placed in a particular group, all have many fundamental similarities in their structure. EXAMPLE
The flipper, wing and arm are, all build on the same pattern but during the course of evolution, each has been modified from its basic pattern to serve a particular and usually highly specialized function, due to its adaptation different to environment or habitate. (Structures that are similar because of their common origin but may differ functionally is known as Homologus)

(B) BIOCHEMISTRY
It is particularly useful, when we classify organism like bacteria, which may all look alike and have an identical cellular structure with the help of chromatography and electrophoresis we can compare the amino acid sequence in the protein of different organisms or the order of bases in their DNA.

(C) CYTOLOGY
Microscopic observations of cell structure are also used to make a fundamental split in the classification of living things. They can be useful at the level of generic and species level. This sort of technique can show delicate difference between species or sub-species, which are identical in many other respects. Specie ? Genus ? Family ? Order ? Class ? Division ? Kingdom

(D) GENETICS
All the morphological, Bio-chemical properties and cytological aspects of an individual, or of a species depend on its genetic constitution. Hence the final tool helping in classifying an organism is Genetics.

TAXONOMIC HIERARCHY
The basic unit of the biological classification is specie. Closely related species are grouped-together into Genera. Genera are grouped into Families, families into order, orders into classes, classes into phyla and phyla or divisions into kingdoms. Each grouping of organisms with in the hierarchy is called taxon and each taxon has a rank and a name. For example class “mammalia” or Genus “Homo”. This ascending series of successively larger, more inclusive groups make up the “Taxonomic Hierarchy”.

CHANGES PROPOSED BY MARGUILES AND SCHWARTZ IN THE FIVE-KINGDOM SYSTEM
Marguiles and schwartz were American Biologist, put forward a modification of Robert Whittaker’s scheme. According to this modification.
• The multicellular alga should be removed from the plant kingdom and placed along with all unicellular organisms, in a new kingdom called “PROTOCTIST” which would replace Whittaker’s Protista kingdom.
• This modification made the plant kingdom a more natural group.
• Due to this modification the kingdom Protoctista became a kingdom that contains all those organisms, which cannot be fitted into any of the other kingdom.

VIRUS
Virus are very minute non cellular bodies considered between living and non-living organisms.

DISCOVERY OF VIRUS
The word virus is derived from a Latin word meaning “Poison”. A Russian Biologist Iwanosky in 1892 discovered Virus.

CHARACTERISTICS OF VIRUS
1. Viruses are non-cellular parasitic entities (obligate parasite)
2. Viruses cannot live and reproduce outside the living cells because they lack the machinery to do so by themselves.
3. The size of the viruses in range 20nm-250nm.
4. Viruses are either virulent destroying the cell in which they occur. While temperate Viruses become integrated into their host genome and remain stable for long period of time.

STRUCTURE OF VIRUS
1. The viruses may be small sphere like or golf balls, like rod shape tadpole and polyhedral.
2. They mainly consist of viral genome, capsids, envelopes and tail Fibers.

(A)GENOME
Viral genomes may consist of a single or several molecules of DNA or RNA.

(B)PROTEIN CAPSID (PROTEIN CORE)
The protein coat that encloses the viral genome is called Protein capsid. It may be of different shapes and mainly made up of proteins sub units called “capsomeres”

(C)VIRAL ENVELOPES
In some viruses accessory structure called Viral Envelopes are present that help them in infecting their host. They are membranes that enclose the protein core.

TAILS AND TAIL FIBRES
Many viruses possesses thread like long tail and tail fibers. These structures help in infecting the host. FIGURE / 5.5 (THE STRUCTURE OF BACTERIOPHAGE)

CLASSIFICATION OF VIRUSES
(A) ON THE BASIS OF MORPHOLOGY
Viruses are generally classified on the basis of Morphology and nucleic acids they contain. e.g. On the basis of morphology, Viruses are classified into rod shape (TMV), spherical (Polio Virus) and Tadpole (Bacteriophage Virus).

(B) ON THE BASIS OF MODES OF ORIGIN
Viruses can be classified on the basis of their mode of origin, which provide a systematic idea of some of their diversity. Following are the main characteristics of these groups:
1. Unenveloped plus strand viruses.
2. Enveloped plus strand RNAViruses.
3. Minus strand RNA Viruses.
4. Viroids
5. Double strand RNA Viruses.
6. Small genome DNA Viruses.
7. Medium genome and large genome DNA Viruses.
8. Bacteriophage.

LIFE CYCLE OF THE BACTERIOPHAGE
The virus that infects the bacteria (mostly E.coli) is known as “Bacteriophage”
Bacteriophage can reproduce by two alternative mechanisms.
1. The lytic cycle
2. The Lysogenic cycle.

(1)THE LYTIC CYCLE
The life cycle of the bacteriophage that eventually ends in death of the host cell is known as “A LYTIC CYCLE”

The following are the stages of lytic cycle.
1. Initially the bacteriophage uses his tail fibers to stick to specific receptor present on the outer surface of E-coli bacteria.
2. The sheath of the viral tail contracts, thrusting a hollow core through the bacterial wall and membrane of the bacterial cell and then phage injects its DNA into the cell.
3. The empty capsid of the phage is left outside the cell.
4. The bacterial cell’s DNA is destroyed (hydrolyzed).
5. The phage DNA takes control over the bacterial metabolic machinery and uses it to produce phage proteins and viral nucleotide.
6. Copies of the phage genome are developed and different parts of the phage come together forming daughter phages.
7. In the last stage of lytic cycle the daughter phages released, hydrolytic enzymes “lysozymes”, which digest the bacterial cell wall.
8. Due to osmosis, bacterial cell swells and finally burst releasing 100-200 daughter phage particles.

2. THE LYSOGENIC CYCLE
The life cycle of the Bacteriophage in which the viral genome replicates without destroying the host cell is known as lysogenic cycle.
Viruses that are capable of using both modes of reproduction with in a bacterium are called “Temperate Viruses”.
The following are the stages of lysogenic cycle.
(1) In this cycle infection of the E-coli cell begins when the phage binds to the surface of cell and injects its DNA.
(2) With in the host cell, the phage DNA molecule forms a circle.
(3) The DNA molecules of Viruses incorporated by genetic recombination into a specific site on the host cell’s chromosome. Now it is known as “Prophage cycle”
(4) The phage genome is mostly silent with in the bacterium.
(5) When E-coli cell prepares to divide, it replicates the phage DNA also, and passes the viral copies to the daughter cells.
(6) This mechanism enables the virus to propagate with out killing the host cell upon which it depends.
At some point, prophage give rise to the active phages that lyses their host cells. It is usually an environmental trigger such as radiations, or the presence of certain chemicals that convert the virus from the lysogenic to the lytic mode.

VIRAL DISEASES
1. ANIMAL DISEASES
(1) Poliomyelitis.
(2) Colds
(3) Encephalitis.
(4) Dengue fever.
(5) Yellow fever.
(6) AIDS
(7) Rabies.
(8) Measles.
(9) Mumps.
(10) Hepatitis.

2. PLANT DISEASES
(1) Tobacco Mosaic Virus (TMV) (Tobacco leaves disease) or (Tobacco Mosaic Disease)

AIDS
CAUSITIVE AGENT
AIDS is stand for Acquired Immuno-Deficiency Syndrome, caused by Human Immune Deficiency Virus (HIDV)

SYMPTOMS
(1) Short flu like illness.
(2) Pneumonia like conditions.
(3) Disfiguring form of Skin Cancer (Kaposi’s Sarcoma)
(4) Weight loss and fever.
(5) Dementia (loss of thoughts)
(6) Diarrhea (loose motion with increasing frequency)
(7) Septicemia (Blood Poisoning)
Severity of the Immuno-Deficiency varies and bouts of illness may persist for years.
HIV mostly infects lymphocytes and causes brain cell damage, in more than 50% of cases. Irreversible dementia and eventual death occurs.

TRANSMISSION
(1) The HIV virus can only survive in the body fluids and transmitted by blood or semen.
(2) In 90% of cases the transmission occurs by ***ual contact. Some other modes of transmission are as follow:
• Unsterilized syringes and needles mostly in intravenous drug abusers.
• By giving blood or blood products already infected with HIV.
• Close contact between infected and non-infected people.
• From an infected pregnant women to her baby through placenta or through breast milk.

CONTROL AND TREATMENT
No particular drug is available for treatment of AIDS but there are some drugs, which are effective against this disease like Azidothymadine, Zidovudine and sumarin.

PREVENTION
• Use of the clean needles and sterilize syringes.
• Education and public awareness about the disease and restricted ***-ual contacts with preventive measures.
• Tranfusion of screened blood and blood products.

HEPATITIS
Hepatitis is an inflammation of the liver cells caused by viral infections, toxic agents or drugs.

SIGNS AND SYMPTOMS
• Jaundice.
• Abdominal pain.
• Liver enlargement.
• Fatigue and fever.

TYPES OF HEPATITIS
There are various types of Hepatitis few of them are as follow:

(1)HEPATITIS “A”
• Cause by non-enveloped RNA virus.
• Transmitted by contact with faeces from infected individual.
• Most common form of Hepatitis world wide.

(2)HEPATITIS “B” (SERUM HEPATITIS)
• Caused by DNA viruses.
• More common in Asians, Africans and male homo***uals.
• Often persist in carrier form without causing any symptoms.
• Transmission mostly occurs through skin contacts, blood transfusion and other medical procedures. (Surgery, NG tube, Catheters)
• The virus of this disease can cause liver cancer mostly in carriers.

TREATMENT AND PREVENTION
• New vaccines against the virus have been produced which are of great importance especially for person who required frequent blood transfusion.

(3)HEPATITIS “C”
• Transmission occurs through mother to child during pregnancy.
• By ***-ual contacts.
• Most common transfusion associated Hepatitis.
• It causes liver cancers more often than HBV.