BT102 Midterm Past Papers 2022 by Admire Group of Zoologist

1. Function of cell membrane factors of bacterial cell death? 5

cell membrane is composed of a phospholipid. molecules arranged tail to tail with heads facing away from each other. This makes lipid molecules to appear as a bilayer. So all membranes enclosing the organelle in the cell or the cell itself look as bilayer structures. This is the basic design of the plasma membrane. Protein and carbohydrates are also inserted into the plasma membrane.

There are some basic functions of cell membrane in bacteria.

1. Selective permeable barrier
2. Passive and Active Transport
3. Respiration in microbes (bacteria)
4. Photosynthesis in microbes
5. Lipid synthesis
6. regulates the transport of substances in and out of the cell.
7. receives chemical messengers from other cell.
8. cell mobility, secretions, and absorptions of substances

• Cell wall parts are transported by a molecule called bactoprenol which is present in the plasma membrane.
• PM has many receptors in it with which various ligands can bind and initiate signals for gene expression etc.

2. Oxidation phosphorylation and mechanism of phosphorylation ? 3

Oxidative Phosphorylation

a. Electrons captured from foods are transferred to co-enzymes such as NAD+ or FAD etc.

Then these electrons pass through a series of electron carriers and then ultimately to the last electron acceptor molecules such as O2 or other inorganic compounds (nitrate, sulphate, carbonate etc) through a series of these electron carriers in system called electron transport chains.

During these events, ATP is generated by chemiosmosis.

B. PHOTOPHOSPHORYLATION

This occurs in plants and chlorophyll containing microbes or photosynthetic cells. In these cells, light energy is finally converted into ATP. An electron transport chain is also involved here. This is summarized in the accompanying diagram above. 3. Dry heat method sterilization? 3 a) Form of dry heat include: b) Dry heat (hot-air oven), c) Flaming (Platinum loop sterilization in the flame of Bunsen burner), d) Incineration (burning to ashes). e) Similarly, moist heat can also be grouped into autoclaving (15psi), boiling at 100oC, and Tyndallization (100oC for 3 consecutive days to sterilize sugar solution that can be degraded by autoclaving) and pasteurization (usually at low temperature than 100oC).

4. F PLUS cell ?? 2

In E. coli, fertility factor (F factor) plasmid was the first plasmid observed to be transferred from one organism to the other, hence those bacteria that have this plasmid are called F+ cells to differentiate from those that do not have one (F-). However, once Fcells acquire F+ plasmid, they also become F+.

Q5. Western blotting explain? Most important (5 marks)

Western Blotting: We can use this technique for the detection of antigen in the serum. Microbial proteins can be separated on SDS-PAGE by electrophoresis and the presence of these proteins can be detected by enzyme-tagged antibodies specific to those proteins. A color band will be seen where the specific protein (antigen) is present on the gel. Please remember that proteins in the gel are first transferred to a paper strip before they could be detected by specific antibodies as seen in the accompanying figure. 6. Function of cell wall of bacteria? 5

a) Cell wall is the most important layer in bacteria. It is rigid layer just outside the plasma

membrane. Most important structure in prokaryotes

b) It provides shape to the organism.

c) It provides protection from osmotic lysis.

d) It is involved in pathogenicity (ability of the organism to cause the

disease). Several antibiotics act on it. e) Each bacterium is enclosed by a rigid cell wall composed of peptidoglycan, a protein-sugar (polysaccharide) molecule. The wall gives the cell its shape and surrounds the cytoplasmic membrane, protecting it from the environment. It also helps to anchor appendages like the pili and flagella, which originate in the cytoplasm membrane and protrude through the wall to the outside. The strength of the wall is responsible for keeping the cell from bursting when there are large differences in osmotic pressure between the cytoplasm and the environment.

7. What is flagellum? And gives its function.

Long filamentous structure that propels bacteria is called flagellum. It helps bacteria to move.

Q8. Name two basic dyes?

In basic dye the color is in the positive ion. e.g I. 1-Crystal violet II. 2-Methylene III. 3-blue Malachite green IV. 4-Safranin

9. What is vertical horizontal gene transfer and write type of lateral gene transfer ? 3

Vertical Gene Transfer

This is a normal way of transferring genes from parents to offspring. This happens when a cell divides. Each daughter cell receives exactly what its parent cell has.

HORIZONTAL GENE TRANSFER

When genes are transferred from cells to cells within the same species, the process is called horizontal gene transfer. This can happen between cells of the same species, or across different species of organisms. Horizontal gene transfer involves a donor and a recipient cell. The recipient cell then incorporates received DNA into its own genome and this genome becomes a recombinant molecule or recombinant DNA. The cell that has this recombinant DNA in it is called a recombinant cell. Three processes are known by which genes can be transferred horizontally from one cell to the other, and they include:

1. Transformation
2. Conjugation
3. Transduction

Q10. Define osmotic pressure, osmotic pressure and plasmolysis?

Osmotic pressure is the force caused by a solution passing through a semi permeable surfaceby osmosis, which is equal to the force required to resist the solution from passing back through the surface. An example of osmotic pressure is the process to filter water.

plasmolysis

If cells are placed in hypertonic solutions, water leaves the cells shrinking the cells and damaging them. This process is called plasmolysis. Plasmolysis is the process in which cells lose water in a hypertonic solution

Q11. What is sporogenesis?

Formation of spores takes place within a vegetative cell and the process is called sporulation or sporogenesis. It is initiated when nutrients become unavailable.

Q12. Why 70% alcohol is more effective than 100% alcohol?

Ethanol, isopropanol are examples. Alcohols denature proteins, and dissolve lipids. Alcohols require water for being more effective. This is the reason that seventy percent alcohol is more effective than 100%. Please note that alcohols can effectively kill vegetative form of bacteria, and fungi but not spores. Alcohols are not very effective on wounds. Commonly used in hand sanitizers.