Ribosomes and mechanism of translation Flashcards Preview

BS2091 Biochemistry I: from genes to proteins > Ribosomes and mechanism of translation > Flashcards

Flashcards in Ribosomes and mechanism of translation Deck (35):
1

What subunits is a prokaryotic ribosome made up of?

70S: 50S + 30S

2

What subunits is a eukaryotic ribosome made up of?

80S: 60S + 40S

3

What is the weight of a prokaryotic ribosome?

2.3 x 10^6 daltons

4

What is the weight of a eukaryotic ribosome?

4.6 x 10^6 daltons

5

What percentage of the prokaryotic ribosome is RNA by mass?

65%

6

What percentage of the eukaryotic ribosome is RNA by mass?

60%

7

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

23S RNA + 5S RNA

8

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

31

9

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

16S RNA

10

How many 'S' proteins does the prokaryotic 30S subunit have?

21

11

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

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

12

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

17S-18S RNA

13

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

45-50

14

How many 'S' proteins does the eukaryotic 40S subunit have?

~30

15

Are there many proteins at the subunit interface of ribosomes?

Very few

16

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

'Extra' proteins

17

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

On the 'outside' of the subunits

18

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

On the 'outside' of the subunits

19

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

Globular proteins

20

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

Protein L15

21

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

Hairpins: they form extended scaffolds on which rRNA is supported

22

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

Hairpins: they form extended scaffolds on which rRNA is supported

23

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

No

24

What does tRNA bridge?

The ribosomal subunit interface (water-free zone)

25

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

Molecular mimicry

26

What does RF1 recognise?

UAG and UAA

27

What does RF2 recognise?

UAA and UGA

28

What enzyme is associated with RF3?

GTPase

29

What are the stop codons?

UAG, UAA, UGA

30

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

Free 70S subunit

31

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

Proteins bind
Act as anti-association factors

32

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

Shine-Dalgarno (S-D) recognition

33

How many tRNAmet does E. coli have?

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

34

What initiates translation in bacteria?

Formyl-methionine

35

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

Transformylase