The genetic code and protein synthesis Flashcards Preview

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Flashcards in The genetic code and protein synthesis Deck (43)
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1
Q

the coded mRNA dependent synthesis of protein

A

translation

2
Q

scientists who cracked the genetic code

A

Nirenberg and matthael

3
Q

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

A

wobble hypothesis

4
Q

formation of aminoacyl-tRNAs

A

aminoacyl tRNA synthetase binds amino acid to tRNA using ATP

5
Q

in prokaryotes what are the sizes of the ribosomal subunits

A

50S and 30S

6
Q

what energy is used during translation

A

GTP

7
Q

protein synthesis occurs in three stages

A

initiation
elongation
termination

8
Q

binding of mRNA, ribosomal subunits and first aminoacyl-tRNA

A

initiation

9
Q

sequential formation of all peptide bonds

A

elongation

10
Q

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

A

termination

11
Q

three sites in the ribosome

A

A site
P site
E site

12
Q

four steps in the formation of the prokaryotic initiation complex

A
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
13
Q

blocks A site until ready for first aa-tRNA

A

IF-1

14
Q

prevents premature binding to 50S subunit

A

IF-3

15
Q

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

A

shine dalgarno sequence

16
Q

prokaryotes initiate translation with

A

N-formyl-met-tRNA

17
Q

what enzyme forms peptide bonds

A

peptidyltransferase

18
Q

how is peptide bond formed

A

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

19
Q

EF-G-GTP hydrolysis promotes

A

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

20
Q

what are the five things you need to complete PCR

A
  1. small amount of DNA
  2. dNTPS to make complementary strand
  3. DNA polymerase
  4. buffer with ATP
  5. DNA primers
21
Q

where is the DNA polymerase from

A

hot springs bacteria Taq

22
Q

what replaces the job of helicase

A

heating the DNA to 90 degrees celcius

23
Q

what is the process for one run of PCR

A

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

24
Q

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

A

2^n where n is the number of cycles

25
Q

what is the job of EF-G

A

using GTP to cause a conformational change resulting in peptide translocation

26
Q

what is the job of EF-Tu

A

delivering the next aa-tRNA to the A site

27
Q

when a stop codon reaches the A site…

A

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

28
Q

what is different about transcription and translation in prokaryotes vs eukaryotes

A

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

29
Q

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

A

polysome

30
Q

what are the ribosomal subunits in eukaryotics

A

40S and 60S

31
Q

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

A

tetracycline

32
Q

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

A

chloramphenicol

33
Q

acts only in prokaryotes to block the translocation reaction on ribosomes

A

erythromycin

34
Q

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

A

alpha-amanitin

35
Q

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

A

post translational modification of proteins

36
Q

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

A

proteolytic cleavage

37
Q

the attachment of various sugar residues to proteins

A

glycosylation

38
Q

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

A

lipophilic modifications

39
Q

activation cascades, tagging for repair/destruction, collagen

A

phosphorylation, methylation, hydroxylation

40
Q

between cys residues to promote tertiary structure

A

disulfide formation

41
Q

excision of peptide segments and joining flanking segments

A

protein splicing

42
Q

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

A

signal peptide and protein targeting

43
Q

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

A

proteasomes