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Block 6 Week 3 Colt > Bacterial Genetics - Kozel > Flashcards

Bacterial Genetics - Kozel Flashcards

1
Q

An operon can (blank or blank) a single gene or a group of genes

A

activate or turn off

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2
Q

An operon is under the control of what two DNA sequences?

A

promoter or repressor

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3
Q

what is quorum sensing?

A

The ability to turn on virulence when sufficient numbers of bacteria are present

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4
Q

What are two examples of quorum sensing?

A

Biofilm production by psedomonas sp. and virulence factors by staph aureus

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5
Q

what is the most common form of gene regulation in bacteria? what is a good example of this?

A

negative regulation; the lactose operon

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6
Q

What are the three control genes in the lactose operon?

A
  1. protomer region of DNA where RNA pol begins transcription
  2. Operon: acts a traffic light for transcription of structural genes
  3. Regulatory genes: codes for repressor protein
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7
Q

In the absence of lactose, the operon is suppressed by (blank)

A

binding of repressor protein to operator sequence

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8
Q

How is the repression of the lactose operon reversed?

A

binding of lactose to the repressor protein

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9
Q

What two regions make up the lac operon?

A

control region and structural regions

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10
Q

what are the two genes within the control region?

A

P and O: promoter and operator

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11
Q

What are the three genes within the structural region?

A

Z, Y, and A

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12
Q

What is regulatory gene in the lac operon?

A

I

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13
Q

The operon is regulated by product of the (blank) gene I

A

regulatory

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14
Q

Explain how the lac operon is suppressed?

A

RNA pol transcribes the repressor mRNA which is made into the repressor protein. Repressor binds to operator region, blocking RNA pol movement

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15
Q

Explain how the lac operon is activated?

A
  1. RNA pol transcribes repressor mRNA; mRNA made into repressor protein
  2. Allolactose binds to repressor protein, preventing it from binding to the DNA
  3. RNA pol transcribes the structural genes
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16
Q

What enzymes do Z, Y, and A code for?

A

B-galactosidase, Permease, and Transacetylase

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17
Q

What is the result of a frameshift mutation?

A

Useless peptide or premature truncation

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18
Q

What is a null mutation?

A

Extensive insertion, deletion, or gross rearrangement

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19
Q

what is the result of a null rearrangement?

A

destroys gene function

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20
Q

what are the two methods of producing a null mutation?

A

recombination or genetic engineering

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21
Q

Is mutation an efficient means for developing antibiotic resistance?

A

NO

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22
Q

What is the uptake of naked DNA?

A

Transformation

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23
Q

What is one-way direct cell-to-cell transfer of DNA?

A

conjugation

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24
Q

conjugation happens through the (blank)

A

sex pilus

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25
Conjugation can transfer antibiotic resistance (between/within) speceis
between!
26
What is transduction?
transfer of bacterial viruses (bacteriophages)
27
Can transduction happen trans-species?
they must be the same or closely related species
28
What is generalized transduction
random host DNA is transferred during phage packaging
29
What is specialized transduction?
Intact genes adjacent to the phage are packaged along with it
30
What was the Griffin experiment?
A mix of heat-killed ecapsulated bacteria (fatal) mixed with nonencapsulated bacteria (nonfatal) caused the mouse to die when injected
31
What did the Griffin experiment show?
bacterial recombination
32
What are the two requriements for transformation?
Cell must be at the end of log growth and it must be the rigth bacterial species such as strep pneumoniae or Niesseria gonorrhea
33
(blank) Can be produced by artificial means, e.g., electroporation or inducing changes in membrane permeability
transformation
34
In transformation, DNA is integrated into chromosome by (blank)
homologous recombination
35
Avery, MacLeod, and MCarty demonstrated what fundamental principle?
DNA carries genetic information
36
What must be present in the recipient cell to allow for conjugation?
F factor (fertility factor)
37
How is F factor maintained in the bacteria?
as a plasmid
38
T/F: plasmids replicate INDEPENDENTLY of the bacterial chromosome
true
39
What the fuck is an episome?
A plasmid that can integrate into the host chromosome
40
During conjugation, how is male/female determined?
male: has conjugative F plasmid female: no plasmid
41
T/F: the F plasmid carries all the genes it needs for its own transfer
true
42
The F plasmid has the ability to initiate DNA synthesis at the (blank)
transfer origin of the plasmid
43
When a bacteria receives the F plasmid, the bacteria gains the designation of?
F+
44
What is the F pilus made of?
repeating units of F pilin
45
Does the F pilus bind to the F- or F+ cell?
binds to F-
46
What is High frequency transfer of chromosomal markers (Hfr)
incorporation of the F plasmid into the host chromosome
47
During conjugation, the Hfr cell will cleave its chromosome at the (blank)
oriT; origin for conjugal transfer
48
Genes adjacent to the F factor go (first/last) and the F plasmd goes (first/last)
first, last
49
How does one map genes using conjugation?
disruption of Hfr transfer at various points in time gives you chromosome fragments of different lengths
50
The integration of the Hfr fragment into the recipient cell happens by (blank)
reciprocal recombination (homologous recombination)
51
What are the two general uses for plasmids?
1. resistance and defense | 2. aggression and virulence
52
T/F: there are resistance genese to almost all antibiotics
treu
53
T/F: there are resistance genes to antibacterial compounds such as heavy metals, mercurials, and toxic anions
true
54
T/F: there are resistance genes to radiation and bacteriophages
true
55
What are bacteriocins?
compounds toxic for other bacteria
56
toxins and attachment proteins make up (blank) factors
virulence
57
What are the two ways a transposon can move WITHIN a cell?
1. from one position to another in the genome | 2. between a plasmid and the genome
58
What is the difference between a simple and complex transposon?
simple: only contains the transposon gene complex: also contains genes for antibiotic resistance, etc.
59
The insertion sequences of transposons are (blank) repeats
inverted
60
What is the function of the inverted repeats in a transposon?
allow recognition by transposase
61
Does transposase require regions of extensive homology to move transposons?
nope! BUT HOMOLOGOUS RECOMBINATION DOES
62
what is the function of transposase?
disconnects DNA from rest of sequence and catalyzes transposition into new location
63
What is transposase specific for?
IS
64
(blank) encodes genes needed for conjugal transfer of resistance
resistance transfer factor (RTF)
65
What type of plasmid contains drug-resistance transposons?
conjugal resistance plasmids
66
what is the r-determinant in a plasmid?
it's what codes for antibiotic Resistance!
67
In conjugal resistance plasmids, what is the mechanism for multiple drug resistance?
r-determinant
68
In conjugal resistance plasmids, what is the mechanism for transfer to new bacteria?
RTF
69
If the plasmid carries multiple resistance genes, treatment with one antibiotic promotes resistance to (blank) antibiotics
multiple
70
many bacterial virulence factors ( like diphtheria toxin) are genes encoded by (blank)
temperate bacteriophage,
71
what type of transduction is used if the bacteriophage is lysogenic?
specialized transduction, because it is integrated into the host chromosome!
72
Describe the lytic bacteriophage life cycle?
1. Phage attaches to host cell and injects DNA 2. Phage DNA circularizes 3. New phage DNA and proteins and synthed and assembled into virions 4. Cell lyses, releasing phage virion
73
Describe the lysogenic bacteriophage life cycle?
1. Phage attaches to host cell and injects DNA 2. Phage DNA circularizes 3. Phage DNA integrates with bacterial c'some via RECOMBINATION 4. Lysogenic bacteria reproduces normally 5. Prophage excises from bacterial c-some initiating lytic cycle
74
What do we call a bacterium that has phage DNA integrated into its chromosome?
prophage
75
by what means is phage DNA incorporated into the host chromosome?
recombination
76
Do bacteriophages use DNA or RNA?
DNA
77
Describe the process of generalized transduction?
1. Phage attaches and injects DNA 2. Phage DNA and proteins replicate and bacterial c-some is broken into pieces 3. Phage DNA AND some bacterial DNA are packaged into individual phage capsules 4. Phage containing only host bacterial c-some DNA infects a new cell 5. Recombination occurs and old-host DNA is incorporated into new-host c-some
78
How is the genotype of the new-host in generalized transduction compared to the genotypes of the donor DNA and itself?
unique
79
Describe the process of specialized transduction?
1. Prophage exists in the c-some of host DNA 2. Phage excises carrying with it an adjacent gene (gal gene in this case) 3. Phage matures, cell lyses, phage released containing gal gene +phage DNA 4. Phage infects a new cell that lacks galactose utilization 5. Prophage and gal gene incorporated into host c-some 6. lysogenic cell can now metabolize galactose

Block 6 Week 3 Colt (4 decks)

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