Biochem Exam 3 Mcshan

Front 1

DNA polymerase III (PolC)

functions

Back 1

DNA synthesis
Multi-proteins complex
3' --> 5' proofreading exonuclease activity

Front 2

primase

Back 2

makes RNA primers

Front 3

DNA gyrase

Back 3

relieves supercoiling

Front 4

DNA ligase

Back 4

seals gaps in DNA strands

Front 5

Cells that are defective for MMR show mutations rates of ____ times higher than normal and said to have ______ phenotype

Back 5

-100-1000 times higher than normal

-mutator phenotype

Front 6

what is the major post-replicaiton DNA repair system?

Back 6

Mismatch repair

Front 7

How does MMR work?

Back 7

1. Uses DNA METHYLATION for strand discrimination between the methylated template (old) strand is distinguished from the unmethylated (new) strand.

2. Corrects the error in the unmethylated strand

3. Replaces up to several thousand baases of DNA around the error

Front 8

How Bases excision repair works?

Back 8

1. a damaged or inappropriate base is removed from its sugar linkage by a GLYCOSYLASE ENZYME which cut the base-sugar bond

2. the AP ENDONUCLEASE then removes the remainder of the damaged nucleotide

3. DNA polymerase and ligase repair the missing base

Front 9

what is the major repair DNA repair system in mammals

Back 9

Nucleotide excision repair

Front 10

How Nucleotide excision repair works?

Back 10

1. Recognizes DNA damage which is "bulky" and creates a block of DNA replication and transcription

2. Cleaves DNA strand containing the damage by ENDONUCLEASES on either side of damage followed by EXONUCLEASE removal of a short segment containing the damaged region (~ 30 bases in mammals)

3. DNA polymerase fills in the gaps

Front 11

know the two enzymes involved in homologous recombination

Back 11

RecA and RecBCD

Front 12

role of RecA

Back 12

-Pairing of two DNAs

-Formation of Holliday intermediates

-Branch migration

-Forms long, multiprotein helical filaments on the DNA strand

Front 13

role of RecBCD enzyme complex

Back 13

-helps initiate homologous recombination

-helicase (unwinding) and nuclease activities

-Recognizes Chi sites:
5' GCTGGTGG 3'

Front 14

know the two enzymes involved in homologous recombination

Back 14

RecA and RecBCD

Front 15

role of RecA

Back 15

-Pairing of two DNAs

-Formation of Holliday intermediates

-Branch migration

-Forms long, multiprotein helical filaments on the DNA strand

Front 16

role of RecBCD enzyme complex

Back 16

-helps initiate homologous recombination

-helicase (unwinding) and nuclease activities

-Recognizes Chi sites:
5' GCTGGTGG 3'

Front 17

Used by bacteriophages (phages, bacterial viruses) to integrate their DNA into the bacterial DNA

Back 17

Site-specific recombination

Front 18

Recombinase aka?

Back 18

Integrase

Front 19

Role of Site-specific recombination

Back 19

-Recombination occurs at a SPECIFIC DNA SEQUENCE that is shared by two molecules (homologous recombination can occur at any shared sequence)

-Can mediate DNA integrase and excision as well as DNA INVERSION

-Mediated by an enzyme (RECOMBINASE) that recognizes that specific sequence

-DOES NOT REQUIRE RecA

Front 20

Two types of transposition?

Back 20

-Simple transposition

-Replicative transposition

Front 21

Simple transpostion

Back 21

"cut and paste" method

leaves a double-strand break in donor strand that must be repaired

Front 22

Replicative transposition

Back 22

-Proceeds via formation of a cointegate intermediate

-Donor and recipient both end up with copies of the transposon

Front 23

____ elements are often associated with antibotic resistance

Back 23

Mobile DNA elements

Front 24

Transposons

Back 24

encode the protein that mediates transposion: transposase enzyme

-targets DNA sequence is duplicated when the transposon inserts itself

Front 25

What are the multiple tasks in the cell homologous recombination is used for?

Back 25

1. DNA Repair

2. Restarting of stalled replication forks

3. Generation of genetic diversity during meiosis

4. DNA Replication

5. Generation of antibody diversity

Front 26

Flucytosine (5-fluorocytosine) target?

Back 26

Antifungal agent (interfere with nucleotide synthesis)

Front 27

Adensosine arabinoside target?

Back 27

Antiviral (Interferance with nucleotide synthesis)

Front 28

Zidovudine (AZT) target?

Back 28

Anti-HIV-1 (reverse transcriptase inhibitor)

(Interference with Nucleotide Synthesis

Front 29

Rifamycin target?

Back 29

antibiotic

-inhibition of DNA-Directed DNA Polymerase

Front 30

Ciprofloxacin target?

Back 30

DNA gyrase inhibitor

-inhibition of DNA Replication

Front 31

Flucytosine (5-fluorocytosine) target?

Back 31

Antifungal agent (interfere with nucleotide synthesis)

Front 32

Adensosine arabinoside target?

Back 32

Antiviral (Interferance with nucleotide synthesis)

Front 33

Zidovudine (AZT) target?

Back 33

Anti-HIV-1 (reverse transcriptase inhibitor)

(Interference with Nucleotide Synthesis

Front 34

Rifamycin target?

Back 34

antibiotic

-inhibition of DNA-Directed DNA Polymerase

Front 35

Ciprofloxacin target?

Back 35

DNA gyrase inhibitor

-inhibition of DNA Replication