Lecture 16

Question 1

What lines the inner surface of the nuclear envelope?

Answer 1

nuclearr lamina

Question 2

What are the nuclear lamina composed of?

Answer 2

Intermediate filaments which:

• maintain nucleus shape
• organise the packing of the DNA

Question 3

What is the function of nuclear pores?

Answer 3

Allow nuclear cytoplasmic exchange

Question 4

What goes IN to the cell through the nuclear pores?

Answer 4

• Energy
• materials
• control signals

Question 5

What leaves, goes OUT of the nuclear pores?

Answer 5

• mRNA
• tRNA
• rRNA

Question 6

What is the structure of the nuclear envelope?

Answer 6

• composed of two membranes

- nuclear pores

Question 7

During interphase regions of chromatin are either called:

Answer 7

• Euchromatin

- Heterochromatin

Question 8

What does euchromatin mean?

Answer 8

DNA is not as tightly condensed

• less dense
• active DNA, used right now

Question 9

What does heterochromatin mean?

Answer 9

DNA is tightly condensed

• dense
• inactive DNA, used for later

Question 10

What do histone proteins do to DNA?

Answer 10

Condenses DNA hellix to form ‘nucleosomes’ beads on string
then to chromatin fibres

DNA condenses from 2nm - 10nm - 30nm - 300m metaphase chromosome