chapter 14

Question 1

the biological polymerization of amino acids into polypeptide chains
- requires mRNA, tRNA, amino acids, and ribosomes

Answer 1

Translation

Question 2

serve as adaptor molecules to adapt the triplet codons in mRNA to the correct amino acid

Answer 2

tRNA

Question 3

base adenine, has a NH2

Answer 3

adenosine

Question 4

deaminated adenosine; base hypoxanthine

Answer 4

Inosine
(rare bases in tRNA)

Question 5

A tRNA has an _ that base-pairs with the codon in the mRNA

Answer 5

anticodon

Question 6

• s catalyze attachment of amino acid to tRNA
• charges (activates) tRNAs with the appropriate amino acid

Answer 6

Aminoacyl-tRNA synthetases

Question 7

where translation occurs

Answer 7

ribosome

Question 8

prokaryotic cells have _ type of ribosome located in the ___

Answer 8

1; cytoplasm

Question 9

eukaryotic cells have __ types of ribosom:

located in

Answer 9

2 ; cytoplasm & organelles

Question 10

• consist of ribosomal proteins and ribosomal RNAs
• have large and small subunits
• rRNAs provide for important catalytic functions associated with translation

Answer 10

ribosomes

Question 11

ribosome: small subunit binds to

Answer 11

mRNA

Question 12

3 distinct binding areas

Answer 12

E,P, and A sites

Question 13

large subunit has _

Answer 13

peptidyl transferase activity

Question 14

• the small and large ribosomal subunits
• GTP
• charged initiator tRNA, Mg2+
• initiation factors

Answer 14

translation initiation requires

Question 15

In bacteria, the AUG start codon is preceded by a _), which base-pairs with a region of the 16S rRNA of the _S small subunit

Answer 15

Shine-Dalgarno sequence (AGGAGG); 30

Question 16

1) small ribosomal subunit binds first
2) fMet tRNA positioned in P site
3) then the large subunit binds

Answer 16

Three sequential steps in initiation phase:

Question 17

in eukaryotic initiation tRNA is designated with _;

• it carries methionine rather than a formylmethionine
• 40s subunit

Answer 17

tRNA met

Question 18

consensus sequence for optimal start codon recognition
- aka Kozak’s consensus

Answer 18

A/G at -3 and AUG G at 1,2,3, 4

Question 19

Small ribosomal subunit binds to 5’ cap, then scans the mRNA for the first AUG codon

Answer 19

initiation phase in eukaryotes

Question 20

Initiation factors bind to the _ cap in mRNA & to the _

Answer 20

5’ ; polyA tail

Question 21

Once right AUG found, the _ subunit joins

Answer 21

60S

Question 22

Addition of amino acids to C-terminus of polypeptide

Answer 22

Elongation phase

Question 23

elongation requires both ribosomal subunits assembled with the mRNA to form the _site and _ site

Answer 23

P (peptidyl) site and A (aminoacyl) site

Question 24

Charged tRNAs ushered into A site by _

Answer 24

elongation factors

Question 25

catalyzes peptide bond formation between the amino acid on the tRNA at the A site and the growing peptide chain bound to the tRNA in the P site

Answer 25

peptidyl transferase

Question 26

uncharged tRNA moves to the _

Answer 26

E (exit) site

Question 27

Release of ribosomal subunits, mRNA, and polypeptide

Answer 27

termination phase

Question 28

_ factors bind to the stop codons

Answer 28

Release

Question 29

mRNAs with several ribosomes translating at once

Answer 29

Polyribosomes or polysomes

Question 30

cleave the polypeptide chain from the tRNA and release it from the translation complex

Answer 30

GTP-dependent release factors

Question 31

bacteria 3 release factors

Answer 31

RF1, 2, 3

Question 32

The initial amino acid incorporated into all proteins

Answer 32

methionine (N-formylmethionine (fmet) in bacteria)

Question 33

binds GTP and facilitates termination process

Answer 33

RF3

Question 34

recognizes UAA and UAG

Answer 34

RF1

Question 35

recognizes UAA and UGA

Answer 35

RF2

Question 36

Eukaryote release factor that recognizes all three stop codons

Answer 36

eRF1

Question 37

Three stop or nonsense codons

Answer 37

UAG; UAA; UGA