Brainscape's Knowledge GenomeTM

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


See full index

1: GENET 270 > Conjugation > Flashcards

Conjugation Flashcards

1
Q

what is conjugatio?

A

plasmid transferred from donor to recipient

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

How does conjugation happen?

A

A donor forms a mating pair using a pilus to interact with recipient

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

When plasmid is transferred, two strands of plasmid separate in what kinds of process? What does this process look like?

A

-process similar to rolling circle replication
-One strand transferred from donor to recipient & two single strands are replicated concurrently with transfer

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

conjugation first observed in 1947 by which scientists? How did they observe it?

A

-Lederberg and Tatum
-mixed together different auxotrophic strains and got strains unlike either of parents

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

What were Lederberg and Tatum possible explanations for their results? (3)

A

-cell fusion
-transforming factors in media
-bacterial sex

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

What was 1st conjugative plasmid discovered?

A

“fertility” (F) plasmid

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

F plasmid has tra genes. What are those genes required for?; plasmid also encodes what kind of system?

A

-transfer
-partitioning system

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

What are three replications origins of F plasmid? which one is functional?

A

RepFIA, RepFIB, RepFIC (only RepFIA/oriV functional)

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

what three characteristics make plasmids a selfish DNA elements?

A

-toxin/anti-toxin systems for post-segregational killing
-genes to prevent induction of SOS response
-genes that block T7 phage development

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

DNA transfer is mediated by tra genes which encode two things: whar are they?

A
  1. Mpf component: mating pair formation
  2. Dtr component: DNA transfer & conjugal replication
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the Mpf component? What is its function?

A

-holds donor & recipient together
-channel through which DNA transferred during mating

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

What is a pilus? Who makes the pilus and what was its function?

A

-10 nm diameter tube made of many copies of pilin protein
-made by donor to attach to receptor on recipient then retracts to draw donor & recipient together into mating pair

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

Pilus in mating pair formation is also ____ secretion systems

A

-Type IV

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

What is Type IV secretion systems?

A
  • multi-protein machine that synthesizes pilus
  • after pilus retraction, it is used as conduit for DNA transfer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Evolutionarily, Type IV secretion systems are conserved in many organisms; what is a secondary function of the system (eukaryotic cells)?

A

-used for the delivery of virulence factors into eukaryotic cells

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

Dtr component involves a relaxosome. What is the relaxosome?

A

complex of proteins that bind at oriT & prepare plasmid for transfer

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

relaxosome mainly involves which protein? what does this protein do?

A

-relaxase
-nick DNA to pass ssDNA through pore

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

What is a TraI relaxase protein and its function in relaxosome?

A
  • site-specific endonuclease
  • nicks & attaches to 5’ end at oriT via transesterification & pilots strand into recipient cell
    -recircularizes transferred strand via transesterification in recipient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

relaxosome also has other proteins (4)

A

-TraY & host IHF (integration host factor): needed for nicking
-TraM & TraD (MPF genes): coordinate DNA processing with transfer apparatus
-TraU (dtr component)
-helicase

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

What do coupling proteins do? example?

A

-signal contact with a recipient cell to the Dtr machinery
-TraD

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

TraD is a DNA translocator that does what?

A

DNA translocator that pumps DNA into recipient cell à related to FtsK (needed to turn type IV protein secreting machine into DNA transfer device)

18
Q

What are the 7 steps of conjugation?

A

1) Formation of mating pairs
2) Coupling protein signals to relaxase
3) Relaxase and helicase make single-strand nick at oriT
4) Relaxase and helicase translocated to recipient cell with DNA
5) Coupling proteins pumps DNA out of donor cell; relaxase seals nick in recipient cell
6) replication of 2nd strand in both donor and recipient; seperation of mating pair
7) left w/ with donor and transconjugant

19
Q

After the initiation of MPF, what happens to plasmid transfer rate? why?

A

-plasmid transfer occurs only sporadically
-due to regulation of traJ expression by FinP & FinO

20
Q

what is traJ? what is FinP? what is FinO

A

-transcriptional activator of tra genes
-sRNA inhbits traJ mRNA translation & stimulates degradation
-chaperone that stabilizes & unfolds FinP

21
Q

how does TraJ regulate conjugation?

A

1) lots of TraJ activates tra genes transcription
2) At first, no FinO made. FinO chaperones bind to FinP antisense RNA & align it with traJ RNA
3) Fin P sRna blocks traJ RNA and cause degradation (tra genes not activated)

22
Q

what is genetic organization of tra region?

A

-oriT
-traM
-traJ
-tra genes
-finO

23
Q

what are 3 types of conjugative elements?

A

-self-transmissible
-mobilizable
-promiscuous

24
Q

self-transmissible conjugative elements encode _____ needed to move amongst cells

A

all functions

25
Q

how are mobilizable conjugative elements transferred? Contains own Dtr systems/referred to as ____ genes.

A

-transferred by self transmissible plasmid (can be mobilized by tra systems)
-mob

26
Q

relaxases of mobilizable plasmids evolved to communicate with ______ of self-transmissible plasmids. in practice, only ____ region is needed for a plasmid to be mobilized by compatible self transmissible plasmid

A

-coupling proteins
-oriT

27
Q

What are the wteps of transfer of mobilizable plasmid

A

1) self transmissible plasmid encode the Mpf system & coupling protein
2) coupling protein signals to relaxase of mobilizable plasmid
3) nick made at oriT of mobilizable plasmid
4) mobilizable plasmid ssDNA transferred (rolling circle)
5) mobilizable plasmid replicated in recipient

28
Q

promiscuous plasmids can transfer DNA between ______ (ex. ________)

A

unrelated species (cyanobacteria, gram-positive, plant)

29
Q

promiscous plasmids contribute to the spread of _____

A

antibiotic resistance (bacteria carrying R plasmids selected for in normal flora, can be passed to pathogens)

30
Q

2 biological roles of conjugation

A

1)antibiotic resistance
2) evolution

31
Q

Conjugative plasmids are major way that antibiotic resistance determinants are spread. also spread through _____ (2)

A

-transduction & transformation

32
Q

conjugative plasmids can transfer chromosomal
DNA between bacteria that can lead to acquisition of new genes/mutations. Two mechanisms: ______ & ______

A
  • by integrating into the chr
  • through imperfect excision of Hfr from the chromosome
33
Q

Transfer of chromosomal DNA by plasmids: integrating into chromosones done by ___ strains

A

-Hfr

34
Q

Hfr stands for ____

A

high frequence of recombination

35
Q

many recombinants form when ____ strain mixed with other bacteria of same strain

A

-Hfr

36
Q

Hfr strains donate chr. DNA of host to a recipient cell due to homologous recombination of F/conjugative plasmid into chromosome (often between ______ elements). Subsequent initiation of conjugation leads to transfer of plasmid and chr.

A

-insertion sequence/IS

37
Q

___ strains are what Lederberg & Tatum observed

A

Hfr

38
Q

Hfr strains: transfer of whole chromosome rare since ______ before this can happen. transfer of entire plasmid sequence rare since ____

A

-mating pairs break apart
-oriT in Hfr strain is in the middle of integrated plasmid

39
Q

Conjugation and transfer of part of the bacterial chromosome from an Hfr donor to an ____recipient, resulting in recombination (changes allele in recipient)

A
  • F-
40
Q

Imperfect excision of Hfr from the chromosome leads to _____

A

F’ factors

41
Q

F’ factors created through a homologous recombination (like Hfr strains) event that leads to excision of ______; often through recombination between IS elements; can be very large

A

-conjugative plasmids + some chr. DNA from the chr

42
Q

uses of conjugation in the lab

A

triparental matings

43
Q

highly efficient triparental matings uses the ability of conjugative plasmids to transfer plasmid DNA used to _____

A

move genes

44
Q

triparental matings uses 3 strains:

A

1) strain carrying self-transmissible plasmid
2) strain carrying mobilizable plasmid with gene(s) to be moved
3) desired recipient strain

45
Q

triparental matings steps (3)

A

1) some self-transmissible plasmid will transfer into strain with mobilizable plasmid
2) quickly spread through strain with mobilizable plasmid because conjugation de-repressed immediately after transfer
3) then can efficiently move mobilizable plasmid to recipient for same reason

46
Q

A toxin-antitoxin system consists of a “toxin” and a corresponding “antitoxin”, usually encoded by _____. The toxin is usually a ____ while the antitoxin can be a ______

A
  • closely linked genes
    -protein
    -protein or an RNA
47
Q

Toxin-antitoxin systems are contained on plasmids. They ensure that only the daughter cells that inherit the plasmid ______ after cell division. If the plasmid is absent in a daughter cell, the ______ is degraded and the stable toxic protein kills the new cell; this is known as _______ aka _______

A

-survive
-unstable antitoxin (need to continually made by plasmid)
-‘post-segregational killing’ (PSK)
-plasmid addiction

1: GENET 270 (15 decks)

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