Ribosomes and mechanism of translation

Question 1

What subunits is a prokaryotic ribosome made up of?

Answer 1

70S: 50S + 30S

Question 2

What subunits is a eukaryotic ribosome made up of?

Answer 2

80S: 60S + 40S

Question 3

What is the weight of a prokaryotic ribosome?

Answer 3

2.3 x 10^6 daltons

Question 4

What is the weight of a eukaryotic ribosome?

Answer 4

4.6 x 10^6 daltons

Question 5

What percentage of the prokaryotic ribosome is RNA by mass?

Answer 5

65%

Question 6

What percentage of the eukaryotic ribosome is RNA by mass?

Answer 6

60%

Question 7

What subunits is a prokaryotic 50S subunit made up of?

Answer 7

23S RNA + 5S RNA

Question 8

How many ‘L’ proteins does the prokaryotic 50S subunit have?

Answer 8

31

Question 9

What subunit is a prokaryotic 30S subunit made up of?

Answer 9

16S RNA

Question 10

How many ‘S’ proteins does the prokaryotic 30S subunit have?

Answer 10

21

Question 11

What subunits is a eukaryotic 60S subunit made up of?

Answer 11

25S-28S RNA and 5.8S +5S RNA

Question 12

What subunits is a eukaryotic 40S subunit made up of?

Answer 12

17S-18S RNA

Question 13

How many ‘L’ proteins does the eukaryotic 60S subunit have?

Answer 13

45-50

Question 14

How many ‘S’ proteins does the eukaryotic 40S subunit have?

Answer 14

~30

Question 15

Are there many proteins at the subunit interface of ribosomes?

Answer 15

Very few

Question 16

The 60S ribosome subunit has ‘extra’ what mainly on its back (non-interface) surface?

Answer 16

‘Extra’ proteins

Question 17

Where do protein-protein interactions occur in eukaryotic ribosomal subunits?

Answer 17

On the ‘outside’ of the subunits

Question 18

Where do protein-protein interactions occur in eukaryotic ribosomal subunits?

Answer 18

On the ‘outside’ of the subunits

Question 19

Many ribosomal proteins have bizarre structures that are quite unlike what?

Answer 19

Globular proteins

Question 20

Give an example of a protein that contains a bizarre structure in a ribosome

Answer 20

Protein L15

Question 21

What do the ribosomal proteins that contain bizarre structures act like?

Answer 21

Hairpins: they form extended scaffolds on which rRNA is supported

Question 22

What do the ribosomal proteins that contain bizarre structures act like?

Answer 22

Hairpins: they form extended scaffolds on which rRNA is supported

Question 23

Are the decoding and peptidyl transferase centre (PTC) on the same ribosomal subunit?

Answer 23

No

Question 24

What does tRNA bridge?

Answer 24

The ribosomal subunit interface (water-free zone)

Question 25

EF-Tu and EF-G are examples of what biological phenomenon?

Answer 25

Molecular mimicry

Question 26

What does RF1 recognise?

Answer 26

UAG and UAA

Question 27

What does RF2 recognise?

Answer 27

UAA and UGA

Question 28

What enzyme is associated with RF3?

Answer 28

GTPase

Question 29

What are the stop codons?

Answer 29

UAG, UAA, UGA

Question 30

What does the ribosome release factor (RRF) plus EF-G generate?

Answer 30

Free 70S subunit

Question 31

During the initiation of translation in bacteria, what binds to the 30S subunit?

Answer 31

Proteins bind

Act as anti-association factors

Question 32

What is the recognition called between the 30S subunit and mRNA during the initiation of translation in bacteria?

Answer 32

Shine-Dalgarno (S-D) recognition

Question 33

How many tRNAmet does E. coli have?

Answer 33

2:
Initiator tRNA (tRNAf) used at AUG or GUG - start codons
Ordinary tRNA used at internal AUG

Question 34

What initiates translation in bacteria?

Answer 34

Formyl-methionine

Question 35

What enzyme catalyses the reaction of met-tRNAf into fmet-tRNAf?

Answer 35

Transformylase