Brainscape's Knowledge GenomeTM

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


See full index

MIM 2 > 17. Microbial Genetics I > Flashcards

17. Microbial Genetics I Flashcards

1
Q

core gene pool

A

chromosome that encodes for all of the necessary functions for survival of the bacteria

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

flexible gene pool

A
  • genes that allow the bacteria to be competitive
  • mobile, can be passed between bacteria
  • carried on: Genomic islands, islets, phages, plasmids, integrons, transposons.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

genomic islands

A
  • gene blocks that have come from somewhere else, often encode virulence factors
  • can code for properties like symbiosis.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

plasmids

A

Small, circular portions of DNA not associated with the nucleoid; carry antibiotic resistance
Can replicate independent of chromosome

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

phages

A

bacterial viruses, play a large part in transferring virulence factors

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

integrons

A
  • gene capture units
  • have 3 things: integrase, a promoter and an “at” site (that captures gene cassettes in the environment that have a corresponding at site)
  • can’t replicate on their own
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

transposons

A
  • can move from one location on a chromosome to another (or on any replicon, like plasmids, phages); involved in antibiotic resistance
  • must be associated with a replicon to replicate.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

transformation

A

free/naked DNA in the environment (from dead bacteria) is taken up by another bacteria and integrated through recombination mechanisms

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

transduction

A

gene is transferred by a bacteriophage

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

conjugation

A

transfer of genes via plasmids

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

how does transformation occur?

A
  • transforming DNA binds DNA binding proteins on cell surface (if cell is competent), uptake of ssDNA
  • competence-specific single-stranded DNA binding proteins bind the DNA
  • RecA proteins guide the single stranded DNA to the chromosome
  • homologous recombination occurs, produces a transformed cell!
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what does homologous (general) recombination require?

A
  • a large area of homology between the DNA sequences
  • participation of host proteins
  • it’s a non-additive process
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

bacteriophages generally don’t have ___

A

membranous components (just a capsid)

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

what are the two types of bacteriophages?

A

virulent and temperate

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

virulent bacteriophages

A
  • always enter the lytic cycle

- successful infection results in death of the infected cell

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

temperate bacteriophages

A

can enter the lytic cycle or establish a quiescent relationship with the infected cell (lysogeny, integrates genome with host)

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

upon integration, the phage is called a:

A

prophage

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

a bacterial cell with a prophage is called a __

A

lysogenic cell

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

ATT sequences

A

homologous sequences on the bacteria and bacteriophage (usually only one site on a bacteria)

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

site specific recombination requires

A
  • an ATT sequence
  • an integrase
  • it’s an additive process
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

lysogenic conversion

A

the phage confers upon the bacteria a new phenotypic trait

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

many bacterial toxigenic diseases (such as cholera) are caused by:

A

phages

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

flexible gene pool arized from ____

A

horizontal gene transfer.

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

4 important features of transformation that occurs via general recombination:

A
  • requires RecA (finds homology and promotes integration of foreign DNA)
  • requires extensive homology bw donor and recipient DNA
  • is a replacement event, NOT additive
  • cell must be in a state of competence to take up free DNA
25
Q

What makes a cell competent? (required for transformation)

A
  • cell secretes a protein, competent factor into environment, which can act in autocrine/paracrine fashion.
  • CF interacts with a cell surface receptor to turn on expression of proteins that will allow the cell to take up transforming DNA.
26
Q

_____ bacteria do not make competence factor, how do these become competent then?

A

Gm Negative – instead recognizes environmental stress or is competent constitutively

27
Q

in the first step of transformation, DNA recognized by the cell surface is ___ stranded, when it enters it is ____

A

dsDNA

ssDNA

28
Q

phages contain only ___ and ___

A

nucleic acid core (DNA/RNA) and protein encapsulation/nucleocapsid.

29
Q

T4 has ___ host range, because …

A

narrow, limited by the cell surface receptors it can bind to.

30
Q

specialized transduction

A

a phage will transduce only specific regions of the bacterial chromosome

31
Q

generalized transduction

A

random fragments of disintegrating host DNA are picked up by the phage during assembly; any gene can be transmitted this way

32
Q

lytic cycle

A

a viral reproductive cycle in which copies of a virus are made within a host cell, which then bursts open, releasing new viruses

33
Q

virulent phages

A

always follows the lytic cycle

34
Q

lysogenic cycle

A

a viral reproductive cycle in which the viral DNA is added to the host cell’s DNA and is copied along with the host cell’s DNA

35
Q

prophage

A
  • phage DNA that’s embedded in the host chromosome, maintained and replicated indefinitely. Occurs during lysogenic cycle of temperate phage.
  • stably inherited by host progeny and noninfectious.
  • REVERSIBLE relationship– prophage can revert to vegetative state and develop lytically.
36
Q

temperate phage reproduces through ___ cycle

A

A phage that is capable of reproducing by either the lytic or lysogenic cycle.
Lysogenic relationship is reversible, can revert to lytic cycle.

37
Q

transducing phages

A

phage particles that contain a piece of bacterial chromosome instead of phage DNA inside the phage coat

38
Q

What’s a Hfr cell?

A

a bacterial cell with the F factor or F plasmid integrated into its chromosome (as an episome). Hfr = high frequency recombination

39
Q

prophage only exists in which phage reproductive cycle?

A

in lysogenic cycle. in lytic cycle no prophage, the phage DNA is not integrated in host chromosome, it just takes over.

40
Q

Which phage cycle takes longer to reproduce phage progeny?

A

lysogenic cycle, bc it depends on replication of the host and trigger that turns on lytic cycle.

41
Q

ONLY after a phage undergoes ____ will all of that phage’s progeny be considered transducing phages

A 
Specialized Transduction
(Generalized = packaging problem; bacterial DNA NOT associated with viral, but packaged anyway
specialized = Bacterial DNA is connected to viral DNA and replicated in progeny)
42
Q

bacterial conjugation in gram negative bacteria

A

1) F+ bacteria makes pilus with F- (recipient)
2) Pilus contracts to bring cells in contact
3) DNA transfer takes place

43
Q

bacterial conjugation in gram positive bacteria

A

Positive = no Pilus involved

  1. Cells come in contact via chemoattraction
  2. Pheromones attract donor cell to recipient.
  3. DNA is directly transferred upon contact
44
Q

major difference between F+/F- mating and Hfr/F- mating

A

F+/F-: Plasmid is replicated and transferred to f- directly
Hfr: plasmid is first added to donor, then that DNA segment is transferred and added to f- (still f- after transfer bc no plasmid is transferred)

45
Q

During ___ mating the plasmid genes AS WELL AS donor genes are integrated into the recipient’s chromosome

A

HFR & F- mating

46
Q

F’ Plasmid

A

F plasmid can be excised from the Hfr cell, if excised imprecisely (taking small fragment of the Hfr chromosome), the resulting plasmid is called F’ Plasmid.

47
Q

generalized transduction:

A
  • random fragments of bacterial chromosome accidently packaged into a viral capsid during lytic cycle (packaging mistake)
  • any gene of the host bacterium can be transferred to recipient, but only bacterial genome is transferred (via transducing phage)
  • doesn’t require lysogeny
48
Q

specialized transduction:

A
  • specific host genes near the prophage are excised (result of imprecise excision)
  • requires prophage and lysogeny
  • bacterial fragments become part of viral genome and are transduced to subsequent hosts, along with phage DNA.
49
Q

abortive transduction:

A

the transferred DNA is not integrated but often is able to temporarily survive and express

50
Q

CRISPR

A
  • clustered regularly interspaced short palindromic repeats
  • viral DNA fragments are inserted into CRISPR array. Acquired immunity against subsequent viral infection and plasmid transfer.
  • Absence of PAM within the CRISPR prevents autoimmunity
51
Q

describe the two processes of bacterial conjugation

A
  • a pilus forms and perhaps transfers DNA or brings the two cells in close contact with one another to enable transfer
  • a chemoattractant gradient brings the two cells into close proximity
52
Q

incompatibility groups

A

plasmids are selected based on these groups such that only one version exists in a population
-this is often used for taxonomy purposes

53
Q

the __ is the plasmid origin used in transfer, the __ is the plasmid origin used in normal replication

A

oriT, oriV

54
Q

how does a plasmid get integrated into the bacterial chromosome?

A

insertion sequences on the plasmid has counterparts on the bacterial chromosome, leading to homologous recombination

55
Q

Hfr plasmid

A

a plasmid + bacterial chromosome

56
Q

what are the mechanisms of plasmid specified resistance?

A
  • efflux pumps
  • degrade enzyme
  • modify enzyme
  • modification of the antibiotic target
  • bypass (specifies a new enzyme that isn’t affected by the antibiotic but does the same thing)
57
Q

Two types of resistance:

A
  • intrinsically resistant– already programmed into the basic organism
  • selective/developed resistance– all strains of an organism are initially sensitive to the challenge, over time a percentage of the strains develop resistance
58
Q

what are the two types of resistance and what is the significance?

A

plasmid and chromosomal

  • plasmid resistance can be transferred horizontally (rapid spread)
  • chromosomal resistance is slower and only transferred to offspring
59
Q

generalized recombination vs. site specific recombination

A

generalized recomb = transformation

site specific recombination = transduction

MIM 2 (14 decks)

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