3-2: Prokaryotic Genetics Flashcards

1
Q

How are genes named

A

First three letters describe function, fourth designated specific gene
Italicized, last letter capitalized

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2
Q

Example of gene name

A

btuC (Vitamin B12 Uptake, gene C)

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3
Q

How are proteins named

A

Same, but not italicized and first letter also capitalized (e.g. BtuC)

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4
Q

What is a mutation

A

Heritable change in the DNA sequence of a genome (substitution, insertions, deletions)

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5
Q

What is the wild-type strain

A

Strain isolated from nature or parent strain

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6
Q

What is the phenotype. Eg.

A

Observable characteristics of an organism
E.g. metabolic, virulence, morphology

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7
Q

What is a genomic locus

A

a specific position on a gene

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8
Q

How are mutations named

A

Add number to gene name
e.g. hisC1

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9
Q

How is a deletion mutation shown

A

Delta symbol

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10
Q

How are phenotypes named

A

Three letters with (+) or (-) symbol
His+ can make histidine

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11
Q

How do we isolate mutagens

A

Can induce mutations
Can isolate mutants by selection (parent does not grow)

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12
Q

Example of something you can select for to isolate mutant

A

Antibiotic resistance

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13
Q

How do you use indicator plates for screening

A

Phenotype linked to colony appearance (colour, fluorescence)

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14
Q

How do you use indicator plates for screening

A

Phenotype linked to colony appearance (colour, fluorescence)

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15
Q

What is a point mutation

A

Mutation to a single base pair within a protein-coding sequence

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16
Q

What are the three kinds of point mutations

A

Silent (different codon, same aa)
Missense (one aa to a different aa)
Nonsense (change in aa to stop codon; premature end to protein)

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17
Q

What is truncation

A

The premature end to a protein sequence due to a nonsense mutation

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18
Q

What is a deletion vs insertion mutation

A

Deletion: DNA lost
Insertion: DNA added

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19
Q

What can deletion or insertion mutations lead to

A

Frameshift mutation (shifts all downstream codons, scrambles sequence) = disruptive

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20
Q

What is a reversion

A

Mutant that acquires another mutation and reverts back to wild-type

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21
Q

What is a suppressor mutation

A

Mutation that compensates for the effects of a prior mutation

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22
Q

What is the natural mutation rate of prokaryotes

A

10^6 to 10^7 per 1000 base pairs per round of replication

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23
Q

What is horizontal gene transfer

A

Acquiring new genetic material (foreign DNA) from the environment

24
Q

Three ways foreign DNA can enter prokaryotic cells

A

Transformation
Transduction
Conjugation

25
What can happen to the DNA once it is inside the cell (horizontal gene transfer)
Be degraded Replicate as separate entity (phage) Be integrated into chromosome (recombination, transposition)
26
What can happen to the DNA once it is inside the cell (horizontal gene transfer)
Be degraded Replicate as separate entity (phage) Be integrated into chromosome (recombination, transposition)
27
Physical exchange of DNA between genetic elements of the same cell
Genetic recombination
28
Important type of genetic recombination
Homologous recombination
29
What does homologous recombination do
DNA repair mechanism (double strand breaks), horizontal gene transfer, genome rearrangements (deletions, insertions)
30
What is the main protein in homologous recombination, what does it do
RecA, binds ssDNA, searches for homologous dsDNA, mediates strand invasion
31
What happens during homologous recombination
DNA strand from one source (chromosome) fused to DNA strand from another (foreign DNA)
32
What is a transposable element
Mobile genetic element, can be inserted into another DNA source
33
What enzyme is involved in transposition. What does it do
Transposase enzyme Recognize inverted repeats, cleaves transposable element of DNA, cleaves another DNA and inserts transposable element into it
34
What are the two kinds of transposable elements
Conservative (cut and paste) Replicative (copy and paste)
35
What are transposons used for in lab
Generate mutant strains
36
Process by which free DNA is incorporated into a recipient cell bringing about genetic change
Transformation
37
Where does the DNA for transformation come from
Lysed cells within their environment
38
How does DNA cross the cell membrane
Cell needs to actively take it up (regulated process)
39
What is it called when cells can take up free DNA
The cell is competent
40
How is DNA captured in competent cells
Pili captures it, retracts, one stand of DNA degraded and other passed through cm
41
What is a bacteriophage
Virus that infects bacteria
42
What is a viruses DNA packaged into
Virions
43
What are the two bacteriophage pathways
Lytic pathway: DNA replicated into new particles using host resources, lyse cell and release to infect new Lysogenic pathway: viral DNA integrated into host DNA (prophage)
44
What is a temperate phage
One that can operate via lytic or lysogenic pathway
45
What is transduction
Virus transfers bacterial DNA from one cell to another
46
What are the two kinds of transduction
Generalized transduction: during lytic cycle, host cell DNA accidentally packaged into viral particle, injected into new cell Specialized transduction: after prophage forms, its DNA is excised from genome but some neighboring host DNA is also packaged then injected into new cell
47
What is conjugation
Horizontal gene transfer requiring cell-cell contact "mating"
48
What mediates conjugation
Conjugative plasmids
49
What is the F plasmid
Fertility plasmid Strains with F plasmid = F+ = donor cell
50
What kinds of cells can mate
F+ (donor) and F- (recipient) only
51
What kind of pilus do F+ cells encode
Conjugative pilus
52
What does the conjugative pilus do
Attaches to other cell, brings them together, forms conjugative bridge
53
What secretion system is used in conjugation
Type four Transfers F plasmid DNA from F+ cell to F- cell
54
What is an Hfr cell
Insertion sequence of F plasmid integrates into chromosome of recipient Part of donors chromosomal DNA transferred Donor DNA incorporated into recipient genome Full F plasmid not transferred, recipient is still F-
55
What acquired genes will be maintained
Those that provide a selective advantage
56
What happens to most acquired DNA
Lost