Lectures 7-15, Jasna part 2

Question 1

Explain the properties of a bacteria cytoplasmic membrane

Answer 1

Fluid-mosaic model, embedded proteins, somewhat fluid, stabilized by hydrogen bonds, hydrophobic interactions and ionic bonds

Question 2

What are capsules and slime layers

Answer 2

Polysaccharide layers that assist in attachment to surfaces and protect against phagocytosis

Question 3

What are gas vesicles

Answer 3

spindle shaped. gas filled structures made of protein and confer buoyancy in planktonic cells and are impermeable to water

Question 4

What is the sec system

Answer 4

Collection of proteins that effect translocation for most of the proteins through the membrane of the cell.

Question 5

What do sec proteins carry

Answer 5

An N-terminal tag called the leader sequence

Question 6

What does the leader sequence do

Answer 6

Prompts the cell to translocate a protein through the membrane of the cell

Question 7

What is the two-component regulatory system

Answer 7

A system where prokaryotes regulate cellular metabolism in response to environmental fluctuations

Question 8

What is quorom sensing

Answer 8

Mechanism by which bacteria assess their population density, ensures a sufficient number of cells are present before initiating a response that requires certain cell density

Question 9

What are antisense RNAs (small RNA)

Answer 9

Antisense RNAs that are corresponding to the non-coding (antisense) strand anneal to mRNA and block translation

Question 10

What are trans-sRNAs (small RNA)

Answer 10

trans-sRNA binds to mRNA with the help of small proteins called RNA chaperones to regulate translation and increase/decrease stability of mRNA

Question 11

What are Riboswitches

Answer 11

RNA domains in an mRNA molecule that can bind small molecules to control translation of mRNA.

Question 12

What are point mutations

Answer 12

Mutations that change only one base pair, can lead to silent, missense or nonsense mutations.

Question 13

What are induced mutations

Answer 13

Mutations made environmentally or deliberately (exposure from UV or radiation)

Question 14

What are transposable elements

Answer 14

Segments of DNA that can move from one site to another site on the same or a different molecule.

Question 15

What is a plasmid

Answer 15

Genetic elements that replicate independently of the host chromosome

Question 16

Difference between selectable and non-selectable mutations

Answer 16

Selectable mutations have a growth advantage over the parent in specific conditions, where as non-selectable dont and are hard to detect.

Question 17

What is the purpose of genome sequencing

Answer 17

Identify new components of cells, therapeutic advantages and replication advantages

Question 18

What is shot-gun sequencing

Answer 18

DNA is broken up into small fragments and then reassembling the sequences by looking for regions of overlap using a computer to find the whole genome sequence

Question 19

Outline the steps in computer identification of ORFs

Answer 19

1. Computer finds start codons
2. Computer finds stop codons
3. Computer counts codons between start and stop codons
4. Computer finds possible RBS
5. Computer calculates codon bias in ORF
6. Computer decides if ORF is genuine
7. List of probable orfs

Question 20

What is the aims test

Answer 20

The aims test uses bacterial mutations to detect for potentially hazardous chemicals. It does this by looking for an increase in mutation of bacteria in prescence of suspected mutagen

Question 21

What is the TCA cycle

Answer 21

The TCA cycle feeds the electron transport chain NADH and FADH2 by completely oxidising pyruvate to CO2. The TCA cycle also generates compounds available for bio-synthetic purposes (oxaloacetate).

Question 22

What does ATP synthase do

Answer 22

ATP synthase is a complex which makes use of the proton potential created by the action of the electron transport chain in mitochondria. It transports a proton down the gradient and uses the energy to complete the phosphorylation of ADP to ATP.

Question 23

What does the electron transport chain do

Answer 23

Electrons enter the ETC and move down the complexes through reaction centre, the lower the reaction centre the higher the afffinity, this creates energy, coupling this with pumping of protons across cytoplasmic membrane to form proton motive force, this force is then used in ATP synthase to form ATP

Question 24

Describe the brief mechanism of translocation

Answer 24

The hydrophobic signal sequence inserts into membrane, the remainder of the protein is threaded into translocon channel with help of accessory proteins. Signal-peptidase (protease) cuts the signal sequence away from the rest of protein which is released into cytoplasm

Question 25

How do you make a phylogenetic tree

Answer 25

Make primers against regions unchanged across species. PCR amplify homologous genes from different species. Find out how different genes of the different species are. Then represents results as a tree