Lecture 11

Question 1

What are the key characteristics of the nucleus?

Answer 1

Cotains most of the cell’s genes
Serves as repository of genetic information
Cell’s control center.

Question 2

Components of the Nucleus

Answer 2

Nuclear Envelope
Nuclear Pores
Nuclear Lamina

Question 3

How many membranes do nuclues’ have?

Answer 3

2

Question 4

What is the inner surface of the nuclear envelope lined with?

Answer 4

Nuclear Lamina

Question 5

What is the nuclear lamina made from?

Answer 5

Intermediate Filaments

Question 6

What are the functions of the Nuclear Lamina?

Answer 6

Helps to maintain shape

Helps to organise the packing of DNA

Question 7

What is the disease that a defective nuclear lamina produces? What are the symptoms?

Answer 7

Hutchinson Gilford Progeria Syndrome.

Accelerated ageing.

Question 8

Functions of the Nuclear Pores

Answer 8

Transportation fo mRNA, rRNA, tRNA out of the nucleus
Coordinate control signals that move into the nucleus
Moving of energy and materials into the nucleus.

Question 9

What are the two things that DNA need to be within the nucleus?

Answer 9

It needs to be well packed, but at the same time it must be easily accessible.

Question 10

Pathway of the Hierarchy of DNA packing

Answer 10

1. DNA wraps around Histone proteins to form a strand of DNA with beads called Nucleosomes (10nm)
2. Nucleosomes then interact with further histone proteins,, form the 30nm fibre.
3. The 30nm fibre then forms more coils to what we see as Metaphase chromosomes.

Question 11

What is the phase that creates more compact DNA?

Answer 11

Interphase

Question 12

Euchomatin is… than DNA. Codes for ….

Answer 12

Less dense DNA, usually codes for genetically active sequences.

Question 13

Heterochromatin is… than DNA

Codes for…

Answer 13

More dense than DNA

Codes for the genetically inactive sequences