Download SHRIMATI INDIRA GANDHI COLLEGE

SHRIMATI INDIRA GANDHI COLLEGE
THIRUCHIRAPALLI
GENERAL MICROBIOLOGY
Two marks:
1.Define bacteria?
These are microscopic,unicellular,prokaryotic
organisms. Ehrenberg established the genus bacterium
Their size ranges from 0.5m to 3micron they are in the form of
rods, spheres, spirals .Flagella, pili are present
2.Define halophiles?
A microorganisms whose growth is accelerated by or
dependent on high salt concentrations these are
chemoorganotrophic, aerobic bacteria & approximately
17 to 23% Nacl for good growth. The cytoplasmic membrane
and ribosomes are stable only at high concentrations of Kcl
3.What is capsule?
The bacterial cells are surrounded by a viscous
substances forming a covering layer or envelope around the cell
wall. This layer is called capsule. It protect the cell against
temporary drying by binding water molecules
4.Define gasvesicles?
These are present in phototrophs &halobacteria.These
enable the cells to alter their specific mass & to float in
water.They lack the capacity for active movement.
5.What is chlorosomes?
These are pigment bearing membranous structure. They
are in the form of thylakoids.They are involved in
photosynthesis.They are found in photosynthetic bacteria
6.Define carboxysomes?
These are present in autotrophic bacteria.these are
polyhedrical bodies that are similar to the size of
bacteriophages.It is found in nitrosomonas.
7.Define magnetosomes?
These are cellular inclusions present in some bacteria
they are sensitive to magnetic field.
8.Define phycobilisomes?
Granules on the surface of thylakoids, which contain
phycobilin pigment.
9.Define PHB?
A chloroform soluble polymer of beta hydroxybutyric
acid .It is occur in the form of intracellular granules within
certain bacteria & can be stained by fat soluble dyes.
10.Give an account of cyanophycean & sulphur
inclusions?
Stores of bound nitrogen are found among the
prokaryotes only in cyanobacteria. These contain cynophycin
granules which consist of a specific polypeptide.
11.Define microbial taxonomy?
It is the classification of microbes based on
physiological, metabolic, genetic & size & shape.
12.Explain Haeckal’s three kingdom concept?
Kingdom;protista (bacteria,fungi,algae,protozoa)
Kingdom;plantae
Kingdom;animalia
13.Define fungi?
Nucleated spore bearing achlorophyllous organism which
generally reproduces sexually & asexually & filamentous,
branched, somatic structure surrounded by cell wall contain
chitin or cellulose.
14.Define algae &?
Algae are chlorophyll bearing thallophytes in the sex
organs are either unicellular or multicellular & not protected by
sterile envelope
15.What is protozoa?
They are unicellular,nonphotosynthetic,eukaryotic organisms
they are under the kingdom protista.
Most are aquatic
16. Give any two culture collection centres?
American Type Culture Collection centre
Northern Regional Research Laborotory.
Five Marks:
1.Explain the morphological types of bacteria ?
Morphology of bacteria
The individual spherical bacterium is called micrococcus.Some
spherical bacteria are arranged in pairs and they are called
diplococci(sl.diplococcus).when the cocci are arranged in four they a
called tetracocci when the cocci are arranged in chains, they are call
streptococci. When the cocci are arranged in clusters like a bunch of
grapes they are called staphylococci
2 Explain the cellwall synthesis & cellwall gram positive?
Cell wall is a very rigid structure that gives shape to the
cell. The main function is to prevent the cell from expanding
and bursting of cell because of uptake of water the rigidity of
the wall can be destroyed by very high pressure or other severe
physical conditions. Most bacterial retain their original shape
during after such treatments.
Gram Positive
Peptidoglycan is present
It is made up of
Polysaccharides and
teichoicacids are present
The outer membranes is absent
It contain low level of lipids
It cannot be affected by
Lysozyme
Eg; staphylococcus aureus
3.Explain the structure & function & types of flagella?
Bacteria posses one or more long unbranched appendages called
Flagella. They are used for locomotion
Types:
When the flagellum is present at one end is called monotrichous
When the flagellum is present at both ends is called
amphitrichous
When the flagellum is present on the surfaces(body fully )
Are called peritrichous
Function:
It is used for locomotion
It is used for attachment of host cells
4.Expain Whittaker’s 5 kingdom concept?
The first classification system to have gained is Robert
H.Whittaker’s 5 kingdom the classification are:
Animalia:
It includes animals & eukaryotic cells
Plantae :
It includes multicellular plants
Monera:
Bacteria
Protista
Fungi
5. what are the major characteristics used in taxonomy
Characteristics used in taxonomy are;
Morphological features are important in microbial taxonomy
for many reasons
Morphology is easy to study and analyze,particularly in
eukaryotic microorganisms
The morphological similarity often is a good indication of
phylogenetic relatedness
Many different morphological features are employed in the
classification & identification of microorganisms
Many growth characteristics are considered as physiological
Characteristics.
6. Explain the structure of fungi?
The plant body of a fungus consists of thread is called hypha
A hypha consists of thin wall & has a inner lining of cytoplasm
A hypha do not have cross walls
The cross walls are called septa a hypha with hypha with septa
called septate
The chemical composition varies.cellulose & chitin are rich in
cellwall the aseptate hyphae have number of nuclei and is called
coenocytic
A fungal plant body usually consists of a mass of hyphae called
mycelium.
7Explain the characteristics of algae?
It is live in aquatic or moist habitats
Chlorophyll & other photosynthetic pigments are found
The are autotrophic in nutrition
Starch is the common reserve food in algae
They may be prokaryotic or eukaryotic
Asexual & sexual reproduction takes place
The plant body consists of either unicellular or multicellular
8.Explain rhodophyta?
It includes 7 orders.it is also called red algae
Red colour chromatrophores which contain excess of
phycoerythrin,chlorophylls,carotenoids,xanthophylls,pyrenoits
Asexual & sexual reproduction are common
It may be unicellular or multicellular
Cellwall is made up of polysaccharides & polyuronic acids
Food reserves are stored as floridean starch
It is mostly occur in marine water
Ten marks:
1.Explain the preservation method of microbes?
There are six types of preservation methods.they are
Transfer on fresh media;
Microbial cultures ae maintained by periodic transfer on fresh
sterile media in tubes the frequency of transfer varies with the
organisms after growth the cultures are stored at 37ºc for 20-30
days to keep the cultures viable to use appropriate growth
medium temperature
Overlaying with mineral oil
The oil must be above the tip of the surface the method is simple
&viability is high it stored at 0º-5ºc
Lyophilization;
The cell suspensions are placed in small vials which are then
frozen by immersing in a mixture of ice & vaccum & stored at
low temperature it provide long term survival without a change
in characters
Storage at low temperature;
Cultures are frozen in the presence of glycerol or
dimethylsulfoxide in liquid nitrogen at 196ºc this method is
called gyogenic preservation
Storage in sterile soil;
It is used for preserving spore forming bacteria & fungi spore
suspensions are added to sterile soil & dried at room
temperature & stored at refrigerator
Storage in silica gel;
Bacteria & yeast are stored at silica gel for 1-2years
2.Explain the Asexual reproduction of algae?
protoplasm of the cell divides into many small parts .Each
parts develop new plants.there are different spores are formed
they are;
Monospores;
They are produced in monosporangium without cell division the
mother cell develops in to monospore & it develop in to a new
individual
Statospores;
These are thickwalled resting spores & it develop into a new
individuals
Paraspores;
The spores are produced from triploid sporophyte
Microspores;
These are small spores the protoplast divides & develop in to a
new individual
Auxospores;
It is produced in unfavourable conditions the protoplast divides
&germinates &into a new individual
Endospores;
The spores are produced within the protoplasm & nucleus these
are found in bluegreen algae.
3.Write the sexual reproduction of fungi?
The process of sexual reproduction begins joining of two
cells & their fusion of protoplasts called plasmogamy the sex
organelles are called gametangia & they produce gametes there
are different types of spores formed in sexual reproduction
Ascospores;
These are single celled spores are produced in a sac called ascus
Basidiospores;
These are single celled spores formed from a club shaped
structure called basidium.
Zygospores;
These are large, thick walled spores formed when the two
hyphae are fuse together
Oospores;
These are formed from a female structure called oogonium
fertilization of the eggs by male gamets & give rise to oospores
The asexual reproduction are also takes place they are;
Sporangiospores;
These are single celled formed from sporangia alpanospores are
non motile.
Conidiospores;
These are formed at the tip or side of hypha small spores are
called microconidia large spores are called macroconidia.
Anthrospores;
These are formed from at the disjointing of hyphal cells.
Chlamydospoes;
These are resistant to adverse conditions these are formed from
vegetative hypha.
Blastospores;
These are formed by budding.
4.Explain the isolation of bacteria & fungi?
Isolation of bacteria;
Soil sample is collected
Serial dilution is performed
It is plated on either nutrient agar
The spread plate or streak plate or pour plate technique is
performed.
Then it is incubated on 37ºc for 24 hrs.
The colonies are formed.
To detect the bacteria is done by biochemical test.
Isolation of fungi;
Soil sample is collected
Serial dilution is performed
It is plated on rose Bengal agar or potato dextrose agar.
Then it is incubated on 37ºc for 4 days
The colonies are formed.
5. What is carboxysomes&PHB & capsules?
These are present in autotrophic bacteria.these are
polyhedrical bodies that are similar to the size of
bacteriophages.It is found in nitrosomonas.
A chloroform soluble polymer of beta hydroxybutyric acid .It is
occur in the form of intracellular granules within certain
bacteria & can be stained by fat soluble dyes.
The bacterial cells are surrounded by a viscous substances
forming a covering layer or envelope around the cell wall. This
layer is called capsule. It protect the cell against temporary
drying by binding water molecules .