Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Medical Microbiology > 4 Bacterial Genetics > Flashcards

4 Bacterial Genetics Flashcards

You may prefer our related Brainscape-certified flashcards:
USMLE® Step 1 flashcards Biology 101 flashcards
1
Q

Do bacteria have relatively large or small genomes?

A

Small

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Bacteria have ………………… DNA.
Bacteria have a …………………. genes.
Bacteria …….. introns.

A

Very little redundant DNA
Couple of thousand genes
Bacteria lack introns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Because bacteria are small it means they can what?

A

Respond quickly to environmental changes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are bacteria able to do with their genes?

A

Quickly switch on when needed and switch off when not needed (upregulation and downregulation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What must gene expression be?

A

Tightly regulated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What factors play a role in the gene expression process? And what do they do?

A

Sigma factors and cAMP - ensure proper transcription takes place in terms of starting and finishing points

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are operons?

A

Genes with similar roles, or those which interact and work together under the same control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Explain replica plates.

A

Replica plates are used to detect changes in bacteria.
Colonies grow on the original plate. Place a cloth (cheesecloth) over a block of wood which is almost the same size as the agar plate. Touch the plate gently with the cloth and transfer this imprint of colonies to fresh media (complete and minimal) and incubate.

By comparing the new plate with the original plate, look for colonies on the old plate which arent on the new plate, this is an indication of mutant colonies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Explain the Ames test.

A

Using bacteria to check for mutagens

Bacteria is added to the plate, the suspected mutagen is added and plate is incubated. If the chemical is a mutagen then many colonies will form, if not a mutagen, fewer colonies will form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How many chromosomes can DNA have?

A

One but they can have other forms of DNA present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where are most of the essential genes located?

A

On the bacterial chromosome (single copy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What do plasmids contain?

A

Non-essential (luxury) genes - can be multiple copies

This includes for antibiotic resistance, conjugation and virulence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are transposons and insertion sequences able to do?

A

Move from one position in the genome to another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens if a transposon inserts in the middle of a gene? And what is it good for?

A

Then it will lose its function.

Good for genetic analysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Explain Transformation.

A

Bacterial chromosome from a lysed cell breaks up and is then taken up by a recipient cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Give an example of some genera/species that conjugation takes place in.

A

Bacillus and Streptococcus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does the cell need to be in order for transformation to occur?

A

Competent cell

18
Q

How can cells become artificially competent?

A

Changes to the bacteria cell wall are required. Using the correct growth medium at the correct stage of growth, the DNA can then be transformed into the cells

19
Q

What often happens to transformed DNA?

A

DNA will be destroyed by nucleases produced by the recipient cell

20
Q

What is required for the DNA to be incorporated into the bacterial chromosome?

A

Requires the enzyme recA

21
Q

Do all bacterial cells contain plasmids?

A

No

22
Q

What does conjugation require?

A

Cell to cell contact (normally the same species)

23
Q

What does conjugation entail?

A

Plasmids being passed from one bacterium to another

24
Q

How is contact initiated?

A

The pilus on the donor

25
Q

Is the transfer of DNA is unidirectional or multidirectional?

A

Unidirectional - donor to recipient

26
Q

Explain conjugation.

A

Pilus of donor attaches to recipient. It then disassembles drawing the recipient closer. Once they are physically toughing then their cell walls and cytoplasmic membranes fuse allowing a pore to develop and forming a conjugation bridge. DNA moves through this bridge from the donor to the recipient (only one strand is transferred).

27
Q

What happens to the DNA once it enters the recipient cell?

A

Recipient can replicate the ssDNA to become dsDNA. Now DNA is the same in both cells

28
Q

What can conjugation also involve?

A

Extra DNA being transferred (not restricted to plasma)

Also presents an opportunity to pass on chromosomal DNA

29
Q

What are viruses in bacteria also referred to?

A

Bacteriophages (phages)

30
Q

How do viruses kill the cell? And how is this seen?

A

From a central point outwards and can be seen as plaques

31
Q

How are phages produced (think of the graph)?

A

Produces as a series of phases. Graph goes lag (latent), burst, latent, burst, etc.

32
Q

What does transduction entail?

A

A process by which bacterial viruses or phages infect bacteria

33
Q

What does transduction involve?

A

A phage which has come out of a donor cell which has probably been killed will find a new host. It attaches to the recipient and injects its DNA into the cell.

34
Q

Can transduction contain errors?

A

Yes

35
Q

How is DNA packaged into phages?

A

Some phages can package based on size of fragment in the core of the body of the phage

36
Q

What can packaged DNA sometimes contain?

A

Might contain DNA which should not have been included and so can act as a means of transferring DNA from one cell to another

37
Q

What can sometimes happen to the DNA from the phage?

A

It can become integrated into the bacterial chromosome

38
Q

What happens when the DNA from the phage becomes integrated into the bacterial chromosome?

A

The cell becomes resistant to further infection by that phage

39
Q

What is the stage called where the cell becomes resistant to further infection by the phage?

A

Prophage stage

40
Q

How long can a phage exist in the prophage stage?

A

Several generations

41
Q

What happens to the phage following the prophage stage? And why is this a good thing?

A

Excites itself again to become lytic

Good way to avoid competing with other phages (by waiting until the time for infection is more suitable

Medical Microbiology (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions