Replication, Repair, Recombination

Front 1

Base Excision repair is what?
enzymes involved?

Back 1

repairs damage to a single nucleotide. base is removed with glycosylase and replaced with DNA ligase

Front 2

nucleotide excision repair is what?

Back 2

repairs damage 2–30 bases. thymine dimers SS-breaks. UvrABC endonuclease

Front 3

NER Transcription-Coupled Repair (TCR)

Back 3

Deploys high-priority NER repair enzymes to genes that are being actively transcribed.

Front 4

DNA polymerase I

Back 4

103kD mass. 600 turnover number, Pol A structural gene. Conditionally lethal. polyermizes. Exonuclease 3 to 5 and 5 to 3.

Front 5

non-homogenous end-joining

Back 5

a proenzyme binds to random DNAs joints them together after making them fit by cleaving frayed ends

Front 6

SOS response

Back 6

when a cell stopds dividing to specifically repair damaged DNA
error prone and mutagens able to have no proofreading by active Pols

Front 7

Methods to repair DS-DNA breaks

Back 7

recombination repair and non-homologous end-joining

Front 8

Transposons

Back 8

mobile genetic elements

Front 9

homologous recombination

Back 9

two aligned strands are nicked and makes cross over to pair with near complementary strands to make heterlogous DNA by which DNA ligase repairs. Known as holiday junctions.

Front 10

recombination repair

Back 10

1)A single nick breaks during replication fork.
2) RecBCA+ ReA mediated inversion
3)Branch by RuvAB makes holiday junc
4) RuvC resolved holiday junction leaves repication fork in tact. primers

Front 11

homologous end-joining

Back 11

double holliday junction fices DNA break
-DNA synthase and ligase
-resolved to yield 2 intactstrands

Front 12

3 transposon types

Back 12

-insertion sequences
-transposons and regulation
-genes not involved in transposon moved
-composite transposons

Front 13

mechanism of transposons

Back 13

1) staggered ss-cuts made in both strands
2) Each fray end binds to the DNA to form replication fork.
3) replication occurs to make a cointigrie (plasmid fusion)
4)cointigrie resolved into 2 plasmids by resolvase.

Front 14

DNA demethylation

Back 14

transfers matheyl group to Cys residue and is inactivated
O6-alkylguanine-DNA alkyltransferase

Front 15

Base Excision Repair. most frequent type

Back 15

if DNA glyocolase cleaves glycoside bond leaving a ribose with no base. deoxyribose cleaved by AP endonuclease and gap filled in with DNA polymerase or Ligase
-Uracil DNA glycosylase is most frequent occuring.

Front 16

UV causes

Back 16

formation of hydroxyl radical or pyrimidine dimers

Front 17

examples of chemical mutagens and what they do

Back 17

HNO2 nitrous acid deaminates.
Adenine->hypoxomethene -=C
Cytosine->Urical:A
DNA strands break by ROS

Front 18

Thymine Dimer

Back 18

UV light causes a cyclobutyl ring between 2 stacked thymines

Front 19

2 classes of chemical mutation

Back 19

Point mutations: 1 BP replaced by a different one.
Transitions: Purine replaced by purine or pyrimidine
Transversions: purine replaced by pyrimidine or vice versa.
Insertion/Deletion: a pair is removed or added.

Front 20

Projeria

Back 20

disease of rapid premature aging resulting in childhood death. Short telomeres.

Front 21

Mutation

Back 21

an inheritable alteration of genetic information

Front 22

how are tolomeres replicated

Back 22

telemorase makes a segment in a way similar to that of reverse transcriptase

Front 23

telemorase and cancer

Back 23

good drug target for cancer and leads to death of over proliferating cell

Front 24

Initiation of Euk. DNA replication

Back 24

One initiation->5-300kB
replicions->cluster of irigin sites (20-80/chrom) cluster activated

->Helicase binds, SSBholds as SS and DNA Pol-a binds puts RNA primer eplaced by pol-sigma

Front 25

Elongation of Euk. DNA replication

Back 25

Pol-sigma goes bidirectionally until another fork is met
Histone_dissociate when fork approaches and join when fork passes with correct pair made for DNA
RNase H1 removes RNA leaving 1 5'-RNA cleaved by flap endonuclease-1 (FEN1)

Front 26

four ways cells maintain genetic info accurately(bacterial)

Back 26

1) Balanced dNTP's levels
2) 2 step pol III activity
3) pol I and III 3'-5'
exonuclease activity to repair
4) DNA repair systems

Front 27

Euk Replication.
DNA pol a
DNA pol-sigma
DNA pol- gamma

Back 27

alpha-associates w/ primase lays RNA primer to 15 DNA. No exonuclease activity
Sigma-(pol III) associates with sliding clamp(PCNA) and elongates DNA
Gamma-Only in mutochondria

Front 28

Pol III holoenzyme

Back 28

polIII+B subunit(sliding clamp) the B clamp keeps pol III on DNA

Front 29

Then replicaiton is terminated

Back 29

When a segment of DNA codes for replication to step and release complexes two replication forks sites (TerC) by TUS protein which promotes helicase activity

Front 30

Then DNA (2 DS DNA) separated

Back 30

Topoisomerases unlink DNA

Front 31

Replisome

Back 31

Large complex containing 2PolIII enzymes.
T2 lies between

Front 32

Elongation-synthesis of leading and lagging strands

Back 32

Replisome moves along 5'-3'

Front 33

Pol I note

Back 33

Replace DNA fragments

Front 34

How is bacterial relication started?

Back 34

specific resides one bound by DNa A binds DNA B(a helicase) to unwind DNA then SS binding protein (SSB) holds it in SSDNA conformation

Front 35

DNA Gyrase(type II topoisomerase)

Back 35

undices negative supercoiling to facilitate dsDNA->ssDNA

Front 36

Role of primosome. What is it?

Back 36

DNA-B-DNA-G complex
primase->sunthesizes RNA primer for first part of leading strands and each okazaki fragment ~11 nucleotides long

Front 37

DNA Pol I

Back 37

adds nuclotides in 5'-3' direction editing mistakes in both 3'-5' and 5-3

Front 38

DNA pol II

Back 38

DNA repair

Front 39

DNA pol III

Back 39

Replicates DNA in 5'-3' direciton cant nrepair dsDNA

Front 40

Nucleotide Excision Repair

Back 40

responds to helix distortions when UvrABCendonuclease cleaves damaged DNA UVrD displaces fragment and DNA added by Pol I and DNA ligase

Front 41

Xeroderma Pigmentosa

Back 41

disease which NER(nucleotide exicison repair) wasnt functioning leading to sensitivity to sunlight and eye damage.

Front 42

semiconservative replication
-Who discovered

Back 42

1/2 of old DNA strands joints newly synthesized strands.
Meselson and Stahl

Front 43

DNA extends how? which direction?

Back 43

5'-3'. both directions

Front 44

2 nnames to designate strands

Back 44

leading and lagging strand

Front 45

Ames Test

Back 45

a strain of bacteria that is his-(cant make histidine) a suspected mutagen is spread with cells and # of abnormal cells is how carinogenic it is and liver is added to simulate normal metabolism

Front 46

How pyrimidine dimeres restored to monomers?

Back 46

DNA photophosphorylase

Front 47

Cockayne syndrome

Back 47

hypersensitivity of UV radiation, stunted growth developmental disabilities because of a distored DNA template.

Front 48

Mismatch repair

Back 48

Mut, Mut G combine on mismatch to make a leap where mut H and UvRd and endonuclease break off 2 strand where pol III replaces with good DNA