Mcb 250 Exam Ii

Front 1

Differences between Eukaryotic and Prokaryotic Translation?

Back 1

1. scans mRNA for first AUG
2. eukaryotic ribosomes are larger
3. Initiation:
-eukaryotes have no ribosome binding site, cap is recognized
-met-tRNA instead of formyl-Met-tRNA

Front 2

IF1

Back 2

prevents tRNA from binding to the portion of the small subunit that will become part of the A site by binding to the A site

Front 3

IF2

Back 3

GTPase that interacts with small subunit, IF1, and initiator tRNA. Facilitates their association and prevents other tRNAs from associating.

Front 4

IF3

Back 4

prevents formation of 70S ribosomes from 30S and 50S subunits.
Occupies E site.

Front 5

70S initiation complex

Back 5

last step of initiation, which is association of the large subunit to the small subunit after start codon and initiator tRNA base pair and IF3 is relased by conformational change in small subunit

Front 6

function of α-C-terminal domain

Back 6

interacts with UP element

Front 7

mediator complex

Back 7

multi-protein complex that mediates between proteins and the pre-initiation complex

Front 8

B-DNA

Back 8

most stable configuration

Front 9

Top IV

Back 9

Type II topoisomerase
ATP-Dependent
cuts both strands

Front 10

DNA Gyrase

Back 10

Type II topoisomerase
ATP-Dependent
introduces negative supercoils

Front 11

Top I

Back 11

Type I topoisomerase
ATP-Independent
passes ONE strand through another

Front 12

Top III

Back 12

Type I topoisomerase
ATP-Independent
passes ONE strand through another

Front 13

Rank from traveling far to less traveling:
Nicked Circle DNA, Linear, Supercoiled

Back 13

Supercoiled> Linear > Nicked Circle

Front 14

Modifications of N-terminal tails to make histones fall off and allow access to chromosomes:

Back 14

acetylation of lysines
phosphorylation of serines

Front 15

ssB

Back 15

single stranded binding protein.
binds to single strands to prevent reformation of double helix and hairpins from forming

Front 16

RNase H

Back 16

removes RNA primers

Front 17

DNA Pol I

Back 17

removes RNA primers and fills gap with DNA

Front 18

DNA Pol III

Back 18

highly processive, synthesizes DNA starting at RNA primers

Front 19

Ligase

Back 19

fixes nicks in backbone, uses ATP

Front 20

helicase

Back 20

unwinds DNA, requires ATP and DnaC to load

Front 21

DNA Pol III holoenzyme accuracy

Back 21

1) without correct base pairing the incoming dNTP is not positioned correctly for the reaction to occur
2) the 2'-OH of ribonucleotides don't fit in the active sit
3) 3'->5' exonuclease activity removes misincorporated bases

Front 22

DnaB

Back 22

helicase

Front 23

DnaC

Back 23

loader for DnaB(helicase)

Front 24

DnaG

Back 24

primase

Front 25

DnaA

Back 25

replication initiation factor

Front 26

Dam

Back 26

DNA Adenine Methyltransferase
finds sequences GATC and adds a methyl group to the A, which protrudes into the major groove

Front 27

seqA

Back 27

binds hemimethylated oriC, preventing DnaA binding and dam methylation

Front 28

Replication Initiation Controlled by:

Back 28

1)DnaA-ATP levels
2)control of access to oriC (seqA)

Front 29

Eukaryotic DNA Replication differences:

Back 29

-replisome moves more slowly
-multiple ori
-less known
-chromosomes end up shorter after each round

Front 30

Telomerase

Back 30

ribonucleoprotein, reverse transcriptase

Front 31

-35 and -10 promoters

Back 31

-35: TTGACA
-10: TATAAT

Front 32

RnaseP

Back 32

catalyzes maturation of 5' terminus of tRNA

Front 33

RNA Pol I

Back 33

rRNA

Front 34

RNA Pol II

Back 34

mRNA

Front 35

RNA Pol III

Back 35

tRNA

Front 36

Eukaryotic Transcription differences

Back 36

-3 RNA Polymerases
-mRNA is monocistronic
-mRNA is capped and polyadenylated
-splicing of mRNA

Front 37

HAT

Back 37

Histone acetyl transferase
-decreases affinity of histones for chromosomes

Front 38

transition mutation

Back 38

pyrimidine to pyrimidine
purine to purine
T to C
A to G

Front 39

transversion

Back 39

pyrimidine to purine

Front 40

MutS

Back 40

scans DNA for mismatch repair system, recognizes mismatches from the distortion they cause in the backbones

Front 41

MutH

Back 41

activated by MutL, causes a nick on one strand near the site of the mismatch

Front 42

MutL

Back 42

recruited by MutS, required to recruit MutH

Front 43

GTPase

Back 43

protein that binds and hydrolyses GTP

Front 44

aminoacyl-tRNA synthetase

Back 44

charge tRNAs with amino acids

Front 45

where is amino acid attached to tRNA

Back 45

3' terminus at CCA sequence

Front 46

IF1

Back 46

prevents tRNA from binding to the A site

Front 47

IF2

Back 47

facilitates association of initiator tRNA with P site and prevents other tRNA from blocking the P site

Front 48

IF3

Back 48

binds to small subunit and blocks in from associatin with the large subunit

Front 49

EF-Tu-GTP

Back 49

escorts charged tRNA to A site

Front 50

factor binding center

Back 50

does GTP hydrolysis and creates EF-Tu-GDP which dissociates

Front 51

EF-G-GTP

Back 51

moves peptidyl-tRNA from the A-site to the P-site during translocation. drives translocation by replacing tRNA in the A site.

Front 52

EF-Ts

Back 52

stimulates release of GDP from EF-Tu so that EF-Tu can bind GTP again.

Front 53

Eukaryotic Translation Differences

Back 53

1) binding of initator tRNA in small subunit precedes association with mRNA
2) separate set of factors mediates recognition of mRNA
3) scans for first AUG sequences
4)initiator is methinione
5) no RBS

Front 54

peptide bond formation

Back 54

catalyzed by 23S rRNA