Translation

Question 1

Translation

Answer 1

-the production of a polypeptide
based on the codon sequence of an mRNA.
-is coupled with transcription in prokaryotic cells
-occurs in the cytoplasm, after nuclear transcription of mRNA,
in eukaryotic cells

Question 2

The coupling of transcription and translation is present in:

Answer 2

Prokaryotes

Question 3

Multiple
polypeptides can
be translated
from one mRNA
at once in:

Answer 3

both prokaryotes and eukaryotes

Question 4

Two significant regions of a tRNA molecule:

Answer 4

Anticodon and amino acid (3’ end)

Question 5

What does each ribosomal site hold?
A
P
E

Answer 5

A: aminoacyl tRNA
P: the tRNA with growing polypeptide attached
E: a tRNA that will exit

Question 6

Shine Delegrano Sequence

Answer 6

In prokaryotes, location where ribosomes bind to initiate translation. 7-8 units from AUG

Question 7

The Initiation of Translation in bacteria

Answer 7

1. Small subunit and initiator tRNA bind to the 5’ end of the mRNA.
2. Scanning begins to find the correct AUG start codon(euks).
3. Large subunit binds to the small subunit.

Question 8

Put the following events of bacterial transcription in
chronological order.
1. Sigma binds to the promoter region.
2. The double helix of DNA is unwound, breaking hydrogen
bonds between complementary strands.
3. Sigma binds to RNA polymerase.
4. Sigma is released.
5. Transcription begins.

Answer 8

1,3,2,5,4

Question 9

Where is the start codon located?

Answer 9

Immediately downstream of the 5’ UTR.

Question 10

Elongation of Translation

Answer 10

1. Charged tRNA enters at the A site of the ribosome.
2. A peptide bond is created between the amino acids in the A and P sites
3. The bond is broken between tRNA-a.a. in the P site
4. The ribosome translocates toward the 3’ end of the mRNA

Question 11

Wobble Rules

Answer 11

U -> A, G
G-> U, C

Question 12

Where does translation occur?

Answer 12

ribosomes

Question 13

Polyribosome

Answer 13

a messenger rna molecule that is being translated by two or more ribosomes.

Question 14

transfer RNA

Answer 14

an RNA molecule with an anticodon at one end and an amino acid at the other. Each carries a specific amino acid and binds to the corresponding codon in messenger RNA during translation.

Question 15

aminoacyl tRNA

Answer 15

tRNA with an amino acid attached.

Question 16

aminoacyl tRNA synthetases

Answer 16

catlyze the addition of amino acids to tRNA

Question 17

Protein Synthesis

Answer 17

1. An aminoacyl tRNA diffuses into the A site: if it’s anticodon matches a odon in mRNA, it stays in the ribosome.
2. A peptide bond forms between the amino acid held by the aminoacyl tRNA in the A site and the growing polypeptide, which was held by a tRNA in the P site.
3. The ribosome moves relative to the mRNA by one codon, and all three tRNA’s are shifted one position within the ribosome. The tRNa in the E site exits: the tRNA in the A site moves to the P site, The A site is empty and ready for another aminoacyl tRNA.

Question 18

Protein synthesis starts at the ___ end and ends at the ___ end.

Answer 18

Amino, carboxy.

Question 19

Peptidyl transferase,

Answer 19

The peptidyl transferase activity of the ribosome catalyzes peptide bond formation between the adjacent amino acids.

Question 20

How can 61 codons be translated with only 40 tRNAs?

Answer 20

wobbling

Question 21

In bacteria, what does the initiator tRNA code for?

Answer 21

F-Methionine

Question 22

Initiation differences prok vs euk:

Answer 22

Prok: F-Met
Euk: several initiators, ribosome first associates with 5’ cap, and initiator carries normal methionine.

Question 23

What does translocation require?

Answer 23

type of protein, elongation factor.

Question 24

How does translation termination occur?

Answer 24

When the translocating ribosome reaches one of the stop codons (UAA, UAG, UGA), a protein called release factor recognizes the stop codon and fills the A site

Question 25

How does release factor stop translation?

Answer 25

triggers the hydrolysis of a bond that links tRNA in the P site.

Question 26

Polypeptide folding

Answer 26

-post translational modification
-determined by the amino acid sequence
often guided and accelerated by molecular chaperones.

Question 27

Chemical modfication s