Prokaryotic Translation

Question 1

What is the first amino acid added?

Answer 1

N-formylmethionine or fMET

Question 2

first amino acid inserted by

Answer 2

methionyl-tRNAfMET

Question 3

Regular methionyl-tRNAmet is used for the elongation of the polypeptide chain can only bind to

Answer 3

A site

Question 4

How does a ribosome know where to start translation on an mRNA?

Answer 4

mRNA contains a ribosomal RNA binding sequence… Shine Dalgarno sequence

Question 5

– base pairs with the 16s rRNA of the small subunit

Answer 5

Shine Dalgarno sequence

Question 6

Ribosomes are large RNA-protein complexes

composed of two subunits.

Answer 6

10^3 kDa

Question 7

prokaryotes 50S and 30S subunits associate to form a

Answer 7

70s ribosome

Question 8

– measurement of mass based on density

gradient centrifugation

Answer 8

Svedberg units

Question 9

Each – of the ribosome is composed of a set of proteins complexed
with one or more rRNAs

Answer 9

subunit

Question 10

Has multiple Ribosome-binding sites (Shine Dalgarno sequences) so multiple polypeptides can be synthesized –

Answer 10

simultaneously and independently

Question 11

Initiation Factor – binds to 30S subunit to prevent 50S from binding

Answer 11

IF3

Question 12

– helps entry of initial methionyl-tRNAfmet

Answer 12

IF3 & IF1

Question 13

– (GTP-binding protein) binds to the P site and is required for attachment of first aa- tRNA

Answer 13

IF2

Question 14

16S of the small subunit recognize – and binds to mRNA at AUG

Answer 14

Shine- Dalgarno sequence

Question 15

Initiator methionyl-tRNAfMet binds to the start codon AUG at –

Answer 15

P site and IF2

Question 16

When IF3 is release…

Answer 16

50s binds to 30s

Question 17

At the end of initiation,

Answer 17

GTP is hydrolyzed and IF2-GDP and IF1 are released

Question 18

– brings in each new aminoacyl-tRNA to the A site”

Answer 18

EF-Tu-GTP

Question 19

Aminoacyl-tRNA binds to 2nd codon at –

Answer 19

A site

Question 20

Peptide bond is form between the 2 aa by

Answer 20

Peptidyl transferase is rRNA from 50S

Question 21

– drives the translocation step with hydrolysis of GTP”

Answer 21

EF-G-GTP

Question 22

RF1 recognizes –.

Answer 22

UAG and UAA stop codons

Question 23

RF2 recognizes –

Answer 23

UGA and UAA stop codons

Question 24

both release factors require

Answer 24

GTPase RF3

Question 25

After binding of RF1 or 2 with RF3-GTP into the A site

Answer 25

1. The new polypeptide is cleaved from the last tRNA.

2. GTP is hydrolyzed, the subunits are separated

Question 26

In bacteria, ribosomes begin translating mRNA while –

Answer 26

the mRNA is being synthesized

Question 27

Several ribosomes can translate one mRNA –

Answer 27

simultaneously