Animal Cells (Part Two)

Question 1

What is the concentration of proteins and RNA in the cytoplasm?

Answer 1

30mg/ml

Question 2

What ribosome type is present in a

a) prokaryote?
b) eukaryote?

Answer 2

a) In prokaryotes, a 70S ribosome

b) In eukaryotes, an 80s ribosome

Question 3

Name the two subunits of a prokaryotic 70S ribosome.

Answer 3

• 50S

- 30S

Question 4

Name the two subunits of a eukaryotic 80s ribosome.

Answer 4

• 60S

- 40S

Question 5

Name the unit that describes the sedimentation behaviour of particles.

Answer 5

Svedberg Unit (S)

Question 6

What did Theodor Svedberg develop?

Answer 6

• technique for analytical ultracentriguation

- separated pure proteins from each other

Question 7

What is meant by the term polysome?

Answer 7

Numerous ribosomes operating along a single RNA molecule.

Question 8

Give the diameter range of a nucleus.

Answer 8

2-10 micrometres

Question 9

What percentage of the cell volume is a nucleus?

Answer 9

10%

Question 10

Describe the symmetry of nuclear pore complexes.

Answer 10

Eight-fold symmtery

Question 11

Describe the proteins in a single nuclear pore.

Answer 11

Consists of 30 nucleoporins

Question 12

What makes up the nuclear lamina?

Answer 12

A net of fibres

Question 13

What would happen to the nuclear pores without the nuclear lamina present?

Answer 13

They would cluster

Question 14

What forms the intermediate filaments of the nuclear lamina?

Answer 14

Several lamins

Question 15

Give the two components of the nucleolus and their functions.

Answer 15

• Granular component (ribosome assembly site)

- Fibriliar centres (rRNA transcription)

Question 16

Which form of chromatin is transcriptionally active?

Answer 16

Euchromatin

Question 17

Which form of chromatin remains packaged after mitosis?

Answer 17

Heterochromatin

Question 18

What percentage of the DNA is heterochromatin?

Answer 18

10%

Question 19

Give the size of a histone protein.

Answer 19

~100 amino acids

Question 20

What happens to the nucleosome during transcription?

Answer 20

It loosens

Question 21

What is the diameter of the nucleosome?

Answer 21

30nm

Question 22

What is:

a) RNA polymerase I?
b) RNA polymerase II?
c) RNA polymerase III?

Answer 22

a) RNA polymerase I = ribosomal RNA
b) RNA polymerase II = messenger RNA
c) RNA polymerase III = transfer RNA

Question 23

What is RNA polymerase IV? What is it needed for, and where is it found?

Answer 23

RNA polymerase IV = siRNA.
Required for heterochromatin formation.
Found in plants.

Question 24

How many RNA polymerases are found in a prokaryote?

Answer 24

Just one

Question 25

Give the basic steps to transcription.

Answer 25

1. Transcriptional factors bind to the TATA box (in the promoter).
2. RNA polymerase binds to template strand and synthesises exact copy of coding strand.
3. RNA is released, processed and released from the nucleus.

Question 26

Compare transcription and translation in prokaryotes and eukaryotes.

Answer 26

• In prokaryotes, transcription and translation occur in the same compartment. In eukaryotes, they are compartmentalised.
• In prokaryotes, there are many genes on one strand of mRNA. In eukaryotes, there is one mRNA for each gene.