Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Microbiology > Lecture 5: Bacterial Genetics > Flashcards

Lecture 5: Bacterial Genetics Flashcards

1
Q

What is a mutant

A

Offspring from a normal member of a species but genetically distinct from wild type

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

What is a mutation

A

Any heritable change in DNA sequence

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

What is an allele

A

Different forms of the same gene

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

What are isogenic strains

A

Two linages of the same bacterium that have a single change

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

Do mutations occur spontaneously or are they driven by selective pressures

A

Occur spontaneously but if you apply selective pressure you will create mutations that are resistant

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

What is selection

A

Growth condition that allows for growth of only a specific kind of mutant

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

What is a spontaneous base pair change

A

Occurring by insertion of incorrect base during replication

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

What is an induced base pair change

A

Addition of external factors (mutagens) that alter chemical bonds in DNA and need repair

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

What happens to base pairs with UV exposure

A

Form thymine dimer (T-T instead of T-A)

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

CCC encodes for ___

A

Proline

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

What is a silent or synonymous mutation and example

A

Change in base pair that doesn’t change coding of amino acid

CCC- encodes proline but so does CCA, CCG, CCU

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

What is a missense or nonsynonymous mutations

A

Changes in AA
CCU codes for proline but CGC codes arginine, GCC codes alanine

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

What is a null mutation

A

Loss of function of gene being altered

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

Does a nonsynonymous mutation always lead to a change in phenotype

A

No

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

Is mutation always beneficial to bacterium

A

No

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

How does transcription and translation occur in prokaryotes

A

Occurs simultaneously (CTT) because lack nucleus and nuclear membrane so mRNA is produced and ribosomes are immediately added

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

What is polycistronic

A

In prokaryotes there are multiple translation start sites, multiple genes controlled by one promoter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is monocistronic

A

In eukaryotes single translation start site, 1 gene/1 promoter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe how transcription termination can occur with Rho

A

Rho binds rut sites that are not covered by ribosomes, progresses up to the mRNA strand until it hits RNA polymerase and dislodges it

Controls genes produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What type of mutation is a mutation that changes from coding an amino acid to coding a stop codon- lead to early translation termination

A

Nonsense mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the two stop codons

A

UAG and UAA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What type of mutation can cause both early termination of transcription and translation

A

Non-sense mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are frame shift mutations

A

Base deletions or additions that alter the reading frame of the mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is vertical gene transfer

A

DNA replication provides Daugherty cells with copy of parental DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is horizontal gene transfer
Evolutionary process that distributes genes between divergent prokaryotic linages
26
What is transformation
Uptake of naked DNA from the environment and stable incorporation into genome
27
What is transduction
Transfer of DNA by virus or viral vector (bacteriophage)
28
What is transposition
Transposon genes are transferred from one organism to another through copying and insertion processes
29
What is conjugation or mating
Transfer of genetic material between bacteria by direct cell to cell contact between two cells
30
Why do we care that bacterial cells share DNA
Because can turn avirulent pathogen to virulent
31
What is natural competence
Ability of bacterium to take up DNA
32
What are some examples of bacterium with natural competence
Streptococcus pneumoniae, Neisseria gonorrhoeae, Haemophilius influenza
33
How does DNA uptake in gram negative cells
1. Binding dsDNA to outer membrane surface 2. Moving dsDNA across outer membrane 3. Degradation of one DNA strand 4, translocation of ssDNA molecule into cell
34
How does DNA uptake in gram positive cells
1. Binding dsDNA to outer cell surface 2. Degradation of one DNA strand 3. Translocation of ssDNA molecule into cell
35
How do bacteria regulate competence
Quorum sensing
36
What is quorum sensing
Bacterial communication, relays number of cells in an environment based on secreted protein or product
37
Describe the example of quorum sending with Streptococcus pneumoniae
1. Build up of competence stimulating peptide (CSP) due to S. Pneumoniae population increased leads to induction of competence 2. Fratricide- killing of neighboring non-competent cells as sources of DNA 3. CSP1 producing builds up, triggers competence in CSP1, CSP2 remains non-competent 4. Will lyse non-competent and take up DNA that may contain antibiotic resistance genes
38
Competence is critical to the development of ____
Antibiotic resistance
39
What is transduction
Bacteriophage- bacterial viruses infect and move DNA
40
P1 bacteriophage infects what
E. Coli
41
P22 bacteriophage infects what
Salmonella
42
Phage lambda infects what
E. Coli and salmonella
43
What is specialized transduction
Phage transfers small amount of bacterial DNA adjacent to phage DNA in chromosome- produces infections particles with phage DNA
44
What is generalized transduction
Transduction phage- mutation leads to misreading pac sites, carries bacterial DNA
45
DNA loaded into the phage head is recognized by ___
PAC sites bound by tail proteins on the phage
46
What happens to tail protein in generalized transduction
Mutation in tail protein recognize alternate pac sites found commonly on bacterial chromosome so get a mixture of infection particles and bacterial DNA
47
Generalized transduction must have a ___ marker
Selectable
48
What is lytic growth
Phage replicates- produces phage proteins, generates functional viral particle
49
What is lysogenic growth
Phage silently insert into bacterial chromosome and phage DNA is replicated during cell division as if it is bacterial DNA
50
What is a prophage or lysogen
Lytic genes repressed, viral DNA remains silent in host
51
What is a transposon
DNA element that “hop” or transpose from one place in DNA to another
52
How does transposition work via insertion sequence/elements
1. Inverted repeats with transposase in middle 2. Cuts DNA and allows transposon to insert
53
Insertion elements are called __DNA because they provide no benefit to host, only cut and paste
Selfish DNA
54
What are composite transposons
Large transposable elements flanked by insertion sequences that may or may not be identical
55
Composite transposons are typically carrying ___ markers
Antibiotic resistance markers
56
What are noncomposite transposons
Genes involved in transpotion and non-transposition genes are clustered together and flanked by terminal inverted repeat sequences
57
What is the mechanism of transposition
1. Transposition initiated by DNA replicaition 2. dsDNA break is left behind as transposon goes elsewhere to insert 3. Break must be fixed for cell to be viable 4. Repair mechanisms use the other chromosome copy as template- transposon repaired in donor DNA
58
What is the conjugative transposons mechanism
1. Transposon excises from the chromosome and circularizes 2. Genes encoding proteins that form a channel connecting two cells allow for a transfer of ssDNA 3. Each cell has one strand of DNA that is replicated and the transposon re-inserts
59
What are the reasons for using transposons in molecular biology
1. Transpose at high frequency 2. Transpose randomly 3. Easily selectable marker 4. Broad host range
60
What are the common transposons
Tn5 and Tn10
61
T or F: F plasmid is a self-transmissible plasmid with tra genes- transfer apparatus
True
62
What are the two functions of tra in F-plasmid
1. Dtr- DNA transfer and conjugal replication- preparation of DNA for transfer 2. Mpf-mating pair formation- supramolecular structure (pill) to pass DNA to recipient
63
Describe the steps in F plasmid transfer
1. Mating pair is established 2. Single strand DNA is transferred 3. DNA replication occurs in both donor and recipient 4. Cells separate
64
T or F: mobilizable plasmids have their own tra apparatus
False- depend on tra from self-transmissible plasmid or helper plasmid
65
Describe high frequency recombination and F- mating for genetic mapping
F can be integrated into chromosome and use markers that will be moved into recipient cell, over time look for genes transferred to recipient
66
T or F: the longer it takes for a gene to be transferred the further down the road in the chromosome it is located
True
67
Original map of E. Coli chromosome was based on ___
Minutes
68
What are pathogenicity islands
Horizontally acquired selections of bacterial chromosome that encode genes primarily associates with virulence
69
What are the pathogenicity islands associated with salmonella
Island 1 and 2
70
How can you tell DNA was horizontally acquired
1. Look at close relatives 2. Look at GC content 3. Repeat sequences flanking genes
71
SPI2 in salmonella pathogenicity islands is required for what
Replication in macrophages
72
what is the normal GC in salmonella and what is the SPI2 GC content
Normal GC: 52.7% SPI2 GC content: 43%

Microbiology (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions