The genetic code and protein synthesis

Question 1

the coded mRNA dependent synthesis of protein

Answer 1

translation

Question 2

scientists who cracked the genetic code

Answer 2

Nirenberg and matthael

Question 3

base pairing at third position is not as constrained as the other two bases
permits flexibility in codon/anticodon recognition, allowing mRNA translation with less than 64 tRNAS

Answer 3

wobble hypothesis

Question 4

formation of aminoacyl-tRNAs

Answer 4

aminoacyl tRNA synthetase binds amino acid to tRNA using ATP

Question 5

in prokaryotes what are the sizes of the ribosomal subunits

Answer 5

50S and 30S

Question 6

what energy is used during translation

Answer 6

GTP

Question 7

protein synthesis occurs in three stages

Answer 7

initiation
elongation
termination

Question 8

binding of mRNA, ribosomal subunits and first aminoacyl-tRNA

Answer 8

initiation

Question 9

sequential formation of all peptide bonds

Answer 9

elongation

Question 10

stop codon recognition, release of polypeptide and dissociation of ribosome subunits

Answer 10

termination

Question 11

three sites in the ribosome

Answer 11

A site
P site
E site

Question 12

four steps in the formation of the prokaryotic initiation complex

Answer 12

IF-1 and IF-3 bind to the 30S subunit
30S subunit bind to mRNA shine-dalgarno sequence just upstream of AUG
30S slides AUG into the P site  to insure that first AUG is located 
IF-2 and GTP bind to the 30S subunit 
IF-1 falls away
GTP is hydrolyzed
IF-2 and IF-3 fall away
50S subunit attaches to 30S subunit

Question 13

blocks A site until ready for first aa-tRNA

Answer 13

IF-1

Question 14

prevents premature binding to 50S subunit

Answer 14

IF-3

Question 15

a purine rich mRNA sequence just upstream from the AUG start codon

Answer 15

shine dalgarno sequence

Question 16

prokaryotes initiate translation with

Answer 16

N-formyl-met-tRNA

Question 17

what enzyme forms peptide bonds

Answer 17

peptidyltransferase

Question 18

how is peptide bond formed

Answer 18

A site amino acid amino group acts as the nucleophile and attacks the carbonyl site of P site amino acid

Question 19

EF-G-GTP hydrolysis promotes

Answer 19

ribosome movement 5 prime to 3 prime allowing next codon into A site

Question 20

what are the five things you need to complete PCR

Answer 20

1. small amount of DNA
2. dNTPS to make complementary strand
3. DNA polymerase
4. buffer with ATP
5. DNA primers

Question 21

where is the DNA polymerase from

Answer 21

hot springs bacteria Taq

Question 22

what replaces the job of helicase

Answer 22

heating the DNA to 90 degrees celcius

Question 23

what is the process for one run of PCR

Answer 23

heat to 90 degrees to break DNA strands
cool to 40 degrees to allow primers to attache
heat to 70 degrees to allow polymerase to build strands

Question 24

what is the equation to tell how many molecules have been produced per so many cycles of PCR

Answer 24

2^n where n is the number of cycles

Question 25

what is the job of EF-G

Answer 25

using GTP to cause a conformational change resulting in peptide translocation

Question 26

what is the job of EF-Tu

Answer 26

delivering the next aa-tRNA to the A site

Question 27

when a stop codon reaches the A site...

Answer 27

a release factor binds to the A site and all members of the assembly dissociate

Question 28

what is different about transcription and translation in prokaryotes vs eukaryotes

Answer 28

in prokaryotes transcription and translation happen in the same place since there is no nucleus and translation of a protein can be occurring while transcription is still taking place

Question 29

the complex formed when transcription and translation are occurring at the same time

Answer 29

polysome

Question 30

what are the ribosomal subunits in eukaryotics

Answer 30

40S and 60S

Question 31

acts only in prokaryotes to block binding of aminoacyl tRNA to A site in ribosome

Answer 31

tetracycline

Question 32

acts only on prokaryotes to block the peptidyl transferase reaction on ribosome

Answer 32

chloramphenicol

Question 33

acts only in prokaryotes to block the translocation reaction on ribosomes

Answer 33

erythromycin

Question 34

acts only on eukaryotes to block mRNA synthesis by binding preferentially to RNA polymerase II

Answer 34

alpha-amanitin

Question 35

the modification of a newly formed protein that is often required to finish a protein or convert it from its inactive form to its active form

Answer 35

post translational modification of proteins

Question 36

the removal of N-terminal methionine, signal peptides; activation of precursor proteins

Answer 36

proteolytic cleavage

Question 37

the attachment of various sugar residues to proteins

Answer 37

glycosylation

Question 38

acylation and prenylation; allows membrane attachment/interaction; activation of Ras proteins

Answer 38

lipophilic modifications

Question 39

activation cascades, tagging for repair/destruction, collagen

Answer 39

phosphorylation, methylation, hydroxylation

Question 40

between cys residues to promote tertiary structure

Answer 40

disulfide formation

Question 41

excision of peptide segments and joining flanking segments

Answer 41

protein splicing

Question 42

a short peptide chain that directs the post translational transport of a protein to its final destination in the cell

Answer 42

signal peptide and protein targeting

Question 43

giant protein complexes that bind protein molecules with ubiquitin tags and degrades them

Answer 43

proteasomes