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Bio140 > Lecture 31 > Flashcards

Lecture 31 Flashcards

1
Q

Translation: Initiation

A

small subunit binds mRNA
first codon (AUG) on mRNA moves to P site on ribosome
large subunit binds, forming E,P,A sites for translation

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2
Q

translation

A

components: mRNA, tRNA, ribosome
stages: initiation, elongation, termination

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3
Q

Translation: Elongation

A
  • elongation factor (EF-Tu) binds to charged tRNA and to GTP and brings them to A site of ribosome
  • peptide bond forms between AA in P site and AA in A (peptide = bond between AA) catalyzed by peptidyl transferase on ribosome
  • tRNA in P site is empty and tRNa in A site has growing AA chain
  • ribosome translocates(moves to next codon on mRNA)
  • empty tRNA moves to e site, tRna with AA chain –> P site, A site ready to accept next charged tRNA: cycle repeats until the end
  • eventually tRNAs in the E site are ejected
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4
Q

Translation: termination

A
  • stop codon enters A site (UAA, UGA, UAG)
  • stop codons do not bind tRNA, bind release factors
  • dissociate entire complex, releases new protein
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5
Q

Messenger RNA (mRNA)

A

made up of codons, uses bases U, A, C, G

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6
Q

codon

A
  • a block of information on mRNA, made of a set of 3 bases; specifies an amino acid
  • 64 possible codons for only 20 amino acids
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7
Q

Transfer RNA (tRNA)

A
  • 2D structure: clover leaf
  • 3D structure: L-shape
  • 2 functional ends: acceptor stem that binds amino acid (3’) and anti-codon loop of 3 sequential nucleotides that are complimentary to 1 codon on mRNA
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8
Q

initiator tRNA

A

charged with special amino acid (formylmethionine aka fmet)

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9
Q

ribosome

A

site of protein synthesis (where translation occurs) composed of protiens, enzymes (peptidyl transferase), ribosomal RNA (rRNA) when large and small subunits come together, they form 3 binding sites (P, A, and E)

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10
Q

stop codons

A

UAA, UGA, UAG

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11
Q

start codon

A

AUG

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12
Q

formylmethionine

A

charges initiator tRNA

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13
Q

elongation factor (EF-Tu)

A

binds to charged tRNA and GTP and brings them to A site of ribosome

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14
Q

genetic code

A

sequences of nucleotides that make each strand of DNA unique

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15
Q

Degenerate

A

some amino acids are specified by multiple codons

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16
Q

peptide bond

A

forms between amino acid in P site and amino acid in A site catalyzed by peptidyl transferase on ribosome

17
Q

cloverleaf

A

2D structure due to complementary binding in molecule

18
Q

acceptor stem

A

3’ end binds amino acid (one end of the 3D structure)

19
Q

release factor

A

stop codons bind with these in step 2 of termination, then in step 3 they dissociate the entire complex, releasing new proteins

20
Q

anticodon loop

A

on tRNA is amino acid, tRNA binds to mRNA at the UUU codon

21
Q

charging reaction

A
  • happens on enzyme called aminoacyl tRNA synthase active site, specific amino acid will react with ATP and attach AMP to carboxyl end of amino acid
  • specific tRNA with appropriate anticodon binds to ezyme
  • amino acid transferred to acceptor stem of tRNA with energy from AMP (energy from AMP is used to drive reaction)
  • charged tRNA leaves enzyme and goes to ribosome
22
Q

aminoacyl tRNA synthease

A

where the charging reactions occur

23
Q

anticodon

A

on tRNA is AAA it binds to the UUU codon on mRNA

24
Q

ribosomal small subunit

A

binds mRNA

25
Q

ribosomal large subunit

A

binds after AUG codon binds in P site forming the E P and A sites for translation

26
Q

Peptidyl transferase

A

enzyme catalyzing translation

27
Q

P site (peptidyl)

A

binds tRNA attached to amino acid chain

28
Q

A site (aminoacyl

A

binds charged tRNA

29
Q

E site (exit)

A

binds empty tRNA (no AA attached)

30
Q

GTP

A

gets bound to charged tRNA and brought to the site A of the ribosome

31
Q

amino acids

A

translated from DNA strand, the codons all code for a certain amino acid and they make a protein

32
Q

translocation

A

fourth step of elongation: ribosome moves to the next codon on mRNA, empty tRNA is moved to E site, tRNA with AA chain to the P site, and A site is ready to accept next charged tRNA

33
Q

L-shaped

A

3D structure of tRNA, clover leaf folds in on itself forming L-shaped structure has 2 functional ends: acceptor stem and anti-codon loop

Bio140 (9 decks)

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