Ribosome

Question 1

Speed of ribosome

Answer 1

Ribosomes can join amino acids at a rate of 200 per minute.

Small proteins of 50-250 amino acids can therefore be made in a minute or two however, but larger proteins can take as long as two to three hours. Such as the 30,000 amino acid muscle protein titin.

Question 2

Number of ribosomes

Answer 2

In a mammalian cell there can be as many as 10 million ribosomes. In a prokaryotic cell, such as E.coli, the number is estimated to be about 15,000.

Question 3

Polyribosomes

Answer 3

Where several ribosomes can simultaneously translate the same mRNA molecule

Question 4

70S ribosome composition

Answer 4

30S
50S

Question 5

80S ribosome composition

Answer 5

40S
60S

Question 6

30S subunit

Answer 6

16S rRNA + 21 proteins

Question 7

50S subunit

Answer 7

23S rRNA + 5S rRNA. + 31 proteins

Question 8

40S subunit

Answer 8

18S rRNA + 33 proteins

Question 9

60S subunit

Answer 9

28S RRNA + 5S rRNA + 49 proteins

Question 10

The Nomura 30S assembly map

Answer 10

Proteins separated into primary, secondary, and tertiary binders

S15, S17, S4, S8, S20, S13, and S7 are primary binders

• In general, proteins lower down on the map are on outside of 30S particle.

Question 12

RNA binding sites in the ribosome

Answer 12

Each ribosome has:
a binding site for mRNA
three binding sites for tRNA

Question 13

A site

Answer 13

Aminoacyl-tRNA

Question 14

P site

Answer 14

Peptidyl-tRNA

Question 15

E site

Answer 15

Exit site

Question 16

When were ribosomes first studied

Answer 16

Pallade in the 1950s

Question 17

Which subunit binds first

Answer 17

Small subunit

Question 18

Promoter sequence

Answer 18

Shine-Dalgarno sequence

Question 19

tRNA synthetases

Answer 19

recognise unique structural features of cognate tRNAs

Question 20

Which terminus are new amino acids attached to

Answer 20

Carboxyl terminus

Question 22

Issues with understanding the structure of ribosome

Answer 22

Initial ribosome crystals were not robust and suffered from X-Ray damage

Question 23

Cryo-x-ray crystallography

Answer 23

Uses extremophileliquid nitrogen air stream - 100 degrees

Question 24

Miller and Urey

Answer 24

Origin of life - classic experiments
1950s

Question 25

RNA bases and catalytic properties

Answer 25

RNA bases can form, self combine and then possess catalytic properties Work better than enzymes at low temperatures

Question 26

Conserved core

Answer 26

Present in all ribosomes Made up of 2 strands of rRNA

Question 27

Rib-X pharmaceuticals

Answer 27

Drug company started by T.Steitz Produce antibiotics based on knowledge of ribosome

Question 28

Why is the ribosome a ribozyme

Answer 28

The catalytic part of the ribosome is composed of the RNA nucleotides

Question 29

What is needed for ribozyme action

Answer 29

Pull on bonds by water molecules