module 2 - 3.10 protein synthesis Flashcards

1
Q

what is the central dogma of molecular biology?

A

DNA —transcription–> / <–reverse transcription– RNA –translation–> polypeptide

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2
Q

what is transcription?

A
  • the process of making a copy of something
  • info held on DNA molecule is transcribed into info held on mRNA molecule
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3
Q

how is a copy of the DNA base sequence made?

A

made as an mRNA molecule by RNA polymerase

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4
Q

what does mRNA do?

A

moves genetic information and genes from nuclear pores to ribosomes

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5
Q

what is translation?

A

the process of conversion of something from one form into another e.g. language

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6
Q

what is the sequence of codons on the mRNA translated into?

A

a sequence of amino acids, making a polypeptide

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7
Q

what does translation use to transfer tRNA molecules?

A

ribosomes

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8
Q

what is 1 language?
what is 2 language?

A
  1. codons
  2. amino acids
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9
Q

why is information in DNA transcribed into mRNA?

A

so it can be used multiple times

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10
Q

what is the first stage of transcription?

A

initiation

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11
Q

what is the promoter region?

A

RNA polymerase binding site for DNA

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12
Q

what is the sense strand of DNA?

A

holds the triplet code for the sequence of amino acids

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13
Q

what is the antisense strand of DNA?

A

does not code for the sequence of amino acids but is complementary in base sequence to the sense DNA strand

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14
Q

what does the antisense strand act as?

A

acts as the template DNA strand for RNA polymerase so that the mRNA has the same base sequence as the sense DNA strand

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15
Q

what is the second stage of transcription?

A

elongation

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16
Q

what is RNA polymerase’s error rate from its proof reading ability?

A

1 in 10^4 to 10^6

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17
Q

what is the fidelity of RNA polymerase making mRNA?

A

high fidelity

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18
Q

how many nucleotides can RNA polymerase synthesize per second?

A

40-80 nucleotides per second

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19
Q

what is the third stage of transcription?

A

termination

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20
Q

what do all polypeptides have as their first amino acid?

A

methionine

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21
Q

why don’t all proteins start with methionine?

A

because some polypeptides go through post translational modification from the golgi

22
Q

if methionine (ATG) is the start codon, what is the codon and anticodon for methionine?

A

codon - AUG
anticodon - UAC

23
Q

what does a tRNA molecule consist of?

A

a single RNA strand - 80 nucleotides long

24
Q

where is the anticodon on a tRNA molecule?

A

at the end (bottom) 3 single stranded bases that are complementary to a codon on mRNA

25
Q

what is the amino acid acceptor site?

A

a short sequence of bases that can bind to the only amino acid that the anticodon is complementary to on the mRNA

26
Q

what do tRNA molecules serve as?

A

the physical link between mRNA and amino acids used to make a polypeptide

27
Q

how many tRNA molecules are there compared to codons?

A

the same amount - there is a tRNA molecule for every codon

28
Q

where are tRNA molecules coded?

A

in the nucleolus

29
Q

what 2 components are ribosomes made from?

A
  • ribosomal RNA (rRNA)
  • proteins
30
Q

what are ribosomes?

A
  • complex macromolecular machines, found within all living cells
  • site of biological protein synthesis
31
Q

what are the 2 subunits of ribosomes?

A
  • small ribosomal subunit that ‘reads’ the mRNA
  • the large ribosomal subunits that has 2 binding sites for tRNA molecules and catalytic site for joining amino acids together
32
Q

which bonds join amino acids?

A

peptide bonds

33
Q

what is the first stage of translation?

A

initiation by forming an initiation complex

34
Q

how does the tRNA anticodon UAC bind to the complementary codon AUG?

A

complimentary base pairing

35
Q

how many tRNA’s are there with the anticodon UAG? and why is this?

A
  • one
  • it can only bind to the amino acid methionine (at he amino acid acceptor site)
36
Q

what is formed when a large ribosome subunit is joined to the party?

A

a ribosome

37
Q

what is the second stage of translation?

A

elongation of the polypeptide

38
Q

what is the second amino acid that is brought into the second tRNA binding site on the ribosome during elongation of the polypeptide?

A

valine

39
Q

what is the catalytic site on the polypeptide called/

A

peptidyl transferase

40
Q

what is peptidyl transferase made of?

A

rRNA

41
Q

what does the catalytic site on the ribosome create?

A

a peptide bond between methionine and valine by a condensation reaction

42
Q

what happens to the first tRNA (UAC/ valine)?

A

it detaches to the ribosome and will be bound to the fresh amino acid of methionine

43
Q

how many does the ribosome move along the mRNA strand after the first tRNA molecule detaches?

A

moves along by one codon, the second tRNA bind site is now clear

44
Q

what type of bond is formed from the peptidyl transferase between valine and histidine?

A

peptide bond through a condensation reaction

45
Q

how many amino acids are joined by the ribosome per second?

A

60

46
Q

what is the third stage of translation?

A

termination of a polypeptide

47
Q

how long does the termination of a polypeptide continue for?

A

until ribosome encounters a stop codon on the mRNA

48
Q

what are the stop codons in RNA?

A

UAG
UAA
UGA

49
Q

what are the stop codons in DNA?

A

TAG
TAA
TGA

50
Q

what do stop codons do?

A

cause the ribosomal subunits to detach from each other and from the mRNA

51
Q

when the polypeptide folds up into its final shape, what may it undergo?

A

post translational modification to form a protein (from the golgi)