Bacterial & Viral Genetics

Question 1

What is the typical size of a bacterium?

Answer 1

0.5-5 micrometers

Question 2

Bacteria have rapid reproduction rates. Under lab conditions, E.coli divide every ___ minutes.

Answer 2

20

Question 3

What are the four factors that give rise to high levels of genetic diversity in prokaryotes?

Answer 3

1. Long evolutionary history
2. Rapid reproduction
3. Spontaneous mutations
4. Genetic recombination

Question 4

How do prokaryotes reproduce?

Answer 4

Asexually by binary fission

Question 5

What are the three types of horizontal gene transfer?

Answer 5

1. Transformation
2. Transduction
3. Conjugation

Question 6

What is conjugation encoded by?

Answer 6

Plasmids or transposons

Question 7

What are plasmids?

Answer 7

Circular DNA sections that replicate independently of chromosomes

Question 8

What are transposons?

Answer 8

Transposable elements are mobile sections of DNA that can move within or between genomes

Question 9

What is genetic recombination?

Answer 9

The rearrangement of donor and recipient genomes into new, hybrid genomes, which can result in new phenotypes

Question 10

Viruses are said to be obligate parasites. What does this mean?

Answer 10

They cannot replicate on their own

Question 11

What is transformation?

Answer 11

A recipient, competent cell can uptake foreign DNA from its surrounding environments

Question 12

What is transduction?

Answer 12

Phages carry prokaryotic genes from one host cell to a recipient cell

Question 13

What is conjugation?

Answer 13

Two cells are pulled together and form a mating bridge, through which DNA can pass through

Question 14

During conjugation, two cells form a mating bridge. What is this bridge called?

Answer 14

A sex plus or a F-pilus

Question 15

The ability of a cell to donate its DNA during conjugation relies upon the presence of what in the DNA of the donor cell?

Answer 15

The F-factor

Question 16

What does it mean when a bacteria is considered to be competent?

Answer 16

The bacteria has pores in its cell membrane/cell wall that is able to take up DNA from the environment

Question 17

When a prokaryote contains an F-factor, it is considered to be what?

Answer 17

F-positive

Question 18

If a prokaryote does not contain an F-factor, what is it considered to be?

Answer 18

F-negative

Question 19

Name the process by which F+ cells form a mating bridge with F-cells, copy their plasmid and transfer to the F-cell.

Answer 19

Conjugation

Question 20

Name the process by which competent bacteria take up the DNA from the environment.

Answer 20

Transformation

Question 21

Name the process by which bacteriophages transfer genetic material between the bacteria.

Answer 21

Transduction

Question 22

Staphylococcus aureus is a harmless bacteria that lives on the skin and nasal passages. What is its genetic variant called that can cause flesh-eating disease?

Answer 22

Methicillin-resistant S.aureus (MRSA)

Question 23

Why are viruses considered to be non-living?

Answer 23

1. They are not composed of cells
2. They cannot carry out metabolism
3. They do not reproduce/self-replicate
4. They don’t use energy
5. They cannot maintain homeostasis

Question 24

What is viral genetic material made up of?

Answer 24

Double or single-stranded DNA or RNA

Question 25

Viruses are said to be obligate parasites. What does this mean?

Answer 25

They cannot replicate on their own

Question 26

What are the three components of a virus?

Answer 26

1. Genetic material
2. A protein shell (capsid)
3. An envelope

Question 27

What is a viral capsid made up of?

Answer 27

One or more types of proteins (capsomeres)

Question 28

What is a virus’ ‘host range’?

Answer 28

The number of host species a virus can infect

Question 29

How are viruses classified?

Answer 29

By the Baltimore classification of viruses - this is based on genome type and mechanism of replication

Question 30

How many classes of viruses are there in the Baltimore classification?

Answer 30

Seven

Question 31

Which of the positive (+) or negative (-) strand RNA genomes of viruses can be directly translated?

Answer 31

Positive (+) strand RNA virus genomes can be directly translate

Question 32

What is the replication cycle of a virus?

Answer 32

1. Attachment
2. Entry
3. Integration
4. Synthesis
5. Self-assembly
6. Release

Question 33

Some viruses can integrate into the host genome using what enzyme?

Answer 33

Integrase

Question 34

What type of virus is HIV?

Answer 34

A retrovirus

Question 35

Some retroviruses require what enzyme to reverse transcribe their RNA into DNA before translation?

Answer 35

Reverse transcriptase

Question 36

What are the two pathways in the life cycle of a Phage Lambda?

Answer 36

The Lytic cycle and the Lysogenic cycle

Question 37

What happens during the Lytic cycle of a Phage Lambda?

Answer 37

Injected DNA from the Phage Lambda takes over the bacterial replicative machinery to synthesise new phage DNA and proteins. New phages are assembled and released

Question 38

What happens during the Lysogenic cycle of the Phage Lambda?

Answer 38

The viral proteins break the virus’s and bacteria’s DNA molecules at specific sites and join them together. The viral DNA is integrated and as the bacteria divides, the phage DNA replicates too

Question 39

During the Lysogenic cycle, the viral DNA is integrated into bacterial DNA. What is the viral DNA now known as?

Answer 39

The prophage

Question 40

What is the intrinsic mechanism by which bacteria can become antibiotic resistant?

Answer 40

By mutations

Question 41

What are the extrinsic mechanisms by which bacteria can become antibiotic-resistant?

Answer 41

By transformation, transduction, and conjugation