Module B (2)

Front 1

All parts of the sos repair

Back 1

1. All targets of RecA are cleaved at the dipeptide Ala-Gly

2. Inducible promoter of uvrB repair gene is repressed by LexA under normal conditions

3. RecA activates LexA to self-cleave and this inhibits repressor activity of LexA

Front 2

Retrieval or recombination-repair systems in E. coli do NOT use these proteins (______) to perform these (_______) functions?

Back 2

RecA and SSB; bind to double stranded DNA

Front 3

Default repair systems show bias in error correction. Name the true statements.

Back 3

1. MutS/L removes T from GT and CT mismatch pairs, and is not dependent on GATC methylation.

2. MutM removes oxidated dGTP that is paired with C, but is not able to hydrolyze it as a free nucleotide .

3. MutY removes A from CA and GA mismatches, and does not use MutS/L system.

Front 4

In dam methylation mismatch repair, which protein translocates to the GATC site and is able to bind to two sites simultaneously, thus making a DNA loop?

Back 4

MutS

Front 5

Name all parts of SOS repair

Back 5

1. UV exposure activates RecA

2. Repair uvrB gene is regulated by dual promoter, one constitutive and one inducible

3. LexA repressor binds to the SOS boxes in repair genes promoters and represses their activity under normal conditions

Front 6

What triggers the SOS response

Back 6

1. Crosslinking and alkylating chemical agents

2. Thymine shortage

3. UV irradiation

Front 7

what can happen in the recombination repair of the replication errors

Back 7

1. A stalled replication fork may restart after repairing the damage and use helicase to move the fork forward.

2. A stalled fork may reverse by pairing between the two daughter strands.

3. The structure of the stalled fork is the same as Holliday junction and may be converted to a duplex and ds breaks by resolvases.

Front 8

In dam methylation mismatch repair, which protein acts as the nuclease and nicks the unmethylated strand?

Back 8

MutH

Front 9

parts of SOS repair

Back 9

1. LexA gene itself is de-repressed when LexA is self-cleaved.

2. RecA gene is induced approximately 50-fold, which results in protein induction of 1200 x50=60,000 molecules/cell upon UV.

3. LexA repressor protein normally keeps levels of LexA, RecA, and excision repair enzymes low.

Front 10

Random true facts about msh

Back 10

1. MSH repair system in yeast is homologous to the E. coli MutS/L system.

2. Msh2/Msh6 complex binds single base mismatches, while other proteins do the repairing.

3. Msh2/Msh3 complex binds DNA loops resulting from replication slippage.

Front 11

In dam methylation mismatch repair, which protein recognizes the mismatch?

Back 11

MutS

Front 12

uvr facts

Back 12

1. In uvr (excision repair) mutants, additional RecA mutation eliminates all remaining repair capabilities.

2. In retrieval repair, uvr (excision repair) and rec (recombination) pathways are interconnected.

3. Replication in uvr-/recA- double mutant results in production of DNA fragments as long as distance between individual T-T dimers.

Front 13

When two bases are mismatched, how does the cell know which base to repair?

Back 13

Dam methylation system marks the GATC sequence in the original strand and unmethylated daughter strand is repaired.

Front 14

Mutations in genes that encode __________ represent the Mutator phenotype.

Back 14

repair system proteins, or fidelity of replication proteins

Front 15

What activity is encoded by MutY and what does it do?

Back 15

Adenosine glycosylase; creates apurinic site

Front 16

In dam methylation mismatch repair, what is the signal that causes MutH to join the Mut complex and to nick the unmethylated strand?

Back 16

Recognition of the GATC site by MutS

Front 17

Which function is NOT an activity of RecA?

Back 17

Act as a nuclease, which directly cleaves LexA repressor

Front 18

In yeast mismatch repair system, which proteins ______recognize mismatches, and which are specificity factors_______?

Back 18

Msh2; Msh3 and Msh6