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BMSC 220 > Topic 7 > Flashcards

Topic 7 Flashcards

1
Q

translation is carried out on…

A

ribosomes

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2
Q

mRNA read ….

A

5’ to 3’

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3
Q

tRNA

A

allow for change in “language” (between mRNA and amino acids)

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4
Q

how many possible amino acid encoding codons?

A

61 (+3 STOP)

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5
Q

tRNA read….

A

3’ to 5’ (anticodon)

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6
Q

aminoacyl tRNA

A

special tRNA with a specific amino acid covalently bound at 3’ end

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7
Q

rRNA

A

serves both a structural and functional role; RNA components of ribosomal subunit

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8
Q

anticodon is located on…

A

the tRNA

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9
Q

______ ribosomes are more complex than_________ ribosomes.

A

eukaryotic, prokaryotic

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10
Q

prokaryotic ribosomes

A

70S; 50S large, 30S small

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11
Q

eukaryotic ribosomes

A

80S; 60S large, 40S small

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12
Q

what makes up ribosomes?

A

protein and rRNA

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13
Q

ribosomes are assembled where

A

nucleolus of nucleus

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14
Q

describe ribosome assemble

A
  • ribosomal proteins are imported to nucleolus
  • they attach to pre-rRNA
  • pre-rRNA splits to two (large and small subunit)
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15
Q

tRNAs are synthesized by…

A

RNA pol III

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16
Q

__-shaped structure is critical for proper anticodon function

A

L

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17
Q

3 steps of tRNA processing

A

produced through RNA processing

  • RNA cleavage
  • covalent addition of CCA
  • base modification (RNA editing)
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18
Q

There are _____ different aminoacyl tRNA synthetase

A

20

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19
Q

Each aminoacyl tRNA synthetase recognizes

A
  • correct amino acid

- correct codon on mRNA

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20
Q

Three steps to “charge” a tRNA

A
  • activation of amino acid
  • addition of amino acid to tRNA
  • proper folding of tRNA which can bring amino acid to the ribosome
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21
Q

What are the first 2 controls for specificity of amino acid incorporation into a protein?

A
  • matching correct amino acid to correct tRNA (specificity of enzyme)
  • correct base-pairing of codon and anticodon (specificity of base pairing)
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22
Q

wobble hypothesis

A

some tRNAs can recognize more than one mRNA codon

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23
Q

monocistronic

A
  • one gene codes for one protein

- eukaryotic genome

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24
Q

plycistronic

A
  • one gene codes for more than one protein

- prokaryotic genome

25
Q

3 stages of translation

A
  • initiation
  • elongation
  • termination
26
Q

signals for translation initiation in prokaryotes

A

-Shine-Dalgarno sequence

27
Q

signals for translation initiation in eukaryotes

A

small ribosomal unit binds to 5’ cap of mRNA and slide along until it finds start codon

28
Q

initiation of translation in euk. part 1

A

40S ribosomal subunit + eIFs (eukaryote Initiation Factors) + charged tRNAmet assemble

29
Q

initiation of translation in euk. part 2

A
  • assembly from Step 1 meets up with a mature mRNA (poly AA tail + PABP and 5’ cap)
  • and binds to its 5’m7G cap
30
Q

initiation of translation in euk. part 3

A

Step 2 assembly starts at 5’m7G cap and scans mRNA for AUG start codon

31
Q

initiation of translation in euk. part 4

A
  • Entire complex dissociates from start site (except the 40S subunit and tRNAmet ),
  • 60S ribosomal subunit attaches
32
Q

elongation stage involves which 3 tRNA binding sites?

A
  • A (aminoacyl) site
  • P (peptidyl) site
  • E (exit) site
33
Q

A (aminoacyl) site

34
Q

P (peptidyl) site

35
Q

decoding centre

A

within small subunit; ensures proper aminoacyl tRNA pairs with codon

36
Q

third step in specificity

A

decoding centre

37
Q

elongation of translation step 1

A

tRNAmet is at start site from the cap

38
Q

elongation of translation step 2

A

the next tRNA comes to A site

39
Q

elongation of translation step 3

A

a peptide bond forms between the first two amino acids

40
Q

elongation of translation step 4

A

ribosome moves downstream (A site to P site); translocation

41
Q

elongation of translation step 5

A

repeat steps 2-4

42
Q

termination of translation step 1

A

stop codon ends up in A site

43
Q

termination of translation step 2

A

a releasing factor moves into A site

44
Q

termination of translation step 3

A

poly-peptide chain released

45
Q

termination of translation step 4

A

release factor causes ribosome to disassemble from mRNA

46
Q

post-translational modification

A

chemical modification of a polypeptide chain after translation

47
Q

chaperones

A

protein that keeps protein unfolded until completely synthesized and facilitates folding, but does not incorporate into complex

48
Q

proteolysis or cleavage

A

important for maturation of several proteins

49
Q

signal sequences

A

mature proteins that target proteins to specific cellular compartments

50
Q

some enzymes and hormones require……. to create a functionally active protein

51
Q

types of post-translational modification

A
  • phosphorylation
  • glycosylation
  • lipid addition
  • ubiquitylation
52
Q

phosphorylation

A

small molecules such as phosphate added to regulate protein activity

53
Q

glycosylation

A

carbohydrate addition to form glycoproteins

54
Q

lipid addition

A

lipid addition to form lipoproteins

55
Q

ubiquitylation

A

addition of ubiquitin polypeptide to target proteins for degradation

56
Q

unlike protein cleavage, PTMs are….

A

reversible

57
Q

What processes can ultimately regulate the level of a protein in the cell?

A

regulation of degradation

58
Q

autpophagy

A

protein degradation by lysosomes

BMSC 220 (12 decks)

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