lecture 10 - nucleus

Question 1

What is the phospholipid bilayer surrounding the nucleus called.

Answer 1

nuclear envelope

Question 2

What is the space between the nucleus membranes called?

Answer 2

perinuclear space

Question 3

Describe the nuclear pore complex.

Answer 3

it controls the movement of molecules in and out of the nucleus

Question 4

What are some things that move OUT of the nucleus.

Answer 4

mRNA, tRNA and ribosomal subunits

Question 5

What are some things that move INTO the nucleus

Answer 5

signals (eg. when to turn a gene off), building materials and energy for chemical synthesis

Question 6

What lines the inner surface of the nuclear envelope ad what is it composed of?

Answer 6

nuclear lamina composed of intermediate filaments

Question 7

The perinuclear space is continuous with what.

Answer 7

the lumen of the ER

Question 8

What is the function of the nuclear lamina?

Answer 8

• Maintains shape of the nucleus

- Helps organise the packing of DNA within the nucleus

Question 9

Outline the different stages of DNA organization within the nucleus and how it changes size.

Answer 9

1. double helix structure - 2nm
2. histones H2-H4 interact forming a 10nm diameter fibre nucleosome
3. histones assist DNA to coil up into 30nm fibres
4. this loops to form a 300nm fibre
5. during cell division this coils to form metaphase chromosomes

Question 10

When is the nucleolus visible?

Answer 10

when the cell is not dividing

Question 11

What is the function of the nucleolus.

Answer 11

ribosomal RNA synthesis

which combines with proteins to produce ribosomes

Question 12

How big is the nucleus?

Answer 12

5-10 micrometers

Question 13

Explain the difference(s) between heterochromatin and euchromatin