7.3

Question 1

tRNA

Answer 1

• 70 to 90 nucleotides long
• mRNA is longer
• Distinct pattern, cloverleaf

Question 2

Anticodon

Answer 2

• On end is 3 codon segment that is complementary to codon in mRNA
• On tip is the corresponding a.a

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Question 3

Wobble Hypothesis with Anti-codon

Answer 3

• Because of wobble hypothesis, thereis flexibility in the pairing of the 3rd nucleotide

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Question 4

Aminoacylation

Answer 4

• Aminoacelylationis the process of adding an amino acid to tRNA
• tRNA linked to its correct amino acid —> an aminoacyl-tRNA
• Energy in aminoacyl-tRNA drives the formatin of peptide bonds

Question 5

Ribosomes

Answer 5

• Carries out protein synthesis by translating mRNA into a.a

Made of:
1. Large subunit
2. Small subunit

Question 6

A site

Answer 6

• Aminoacetyle site
• Incoming aminoacetyl-tRNA carrying a.a binds to mRNA

Question 7

P Site

Answer 7

• Peptidyle Site
• Where peptide bonds form between a.a

Question 8

E Site

Answer 8

• Exit Site
• Exiting tRNA leaves the ribosome

Question 9

3 Steps of Translation

Question 10

1. Initiation

Answer 10

• Ribosomal subnit binds to mRNA 5’ cap
• Begins with meth. (start codon)

Initiation: Met-tRNA binds to small ribosomal subunit

• Ribosome moved along mRNA (scanning) until it reaches AUG
• AUG is recognized by anti-codon of tRNA
• Large ribosomal subunit binds to complete ribosome
• End of initiation is when Met-tRNA is in P site

Question 11

2. Elongation

Answer 11

• When Met-tRNA is in P site, and a site is empty
• Next tRNA binds to mRNA in A site (GTP prvides energy for this)
• Peptydal transferase cleaves a.a from P site of tRNA, and binds to a.a in A site of tRNA
• Ribosome moved growing polypeptide from A site to P site, empty tRNA exits from P site to E site

Process repeats until the ribosome reaches the STOP
codon

Question 12

Termination

Answer 12

• Translation STOPS when the A site of a ribosome arrives at a stop codon (UAA, UAG, or UGA) on the mRNA
• Protein releases factors, poly peptide chain, mRNA, and ribosomal subunits dissocosiates
• Protein folding then occurs

Question 13

Translation in Eukaryotes and Prokaryotes

IMAGE

Answer 13

• Multiple ribosomes can translate an mRNA molecule at the same time
• Increase production of proteins
• Called polysome