lecture 10 - cell nucleus

Question 1

What is the typical size of the nucleus?

Answer 1

5-10 micrometres

Question 2

Aside from the nucleus where else are genes in a cell found

Answer 2

Some additional genes are found in the mitochondria and chloroplasts

Question 3

What surrounds the nucleus?

Answer 3

Nuclear envelope

Question 4

How many membranes are in the nuclear envelope?

Answer 4

2

Question 5

What is the space between the 2 membranes of the nuclear envelope?

Answer 5

The perinuclear space

Question 6

What is the outer membrane of the nuclear envelope continuous with?

Answer 6

the rough Endoplasmic Reticulum

Question 7

What is the perinuclear space continuous with?

Answer 7

the lumen of the rER

Question 8

What is the function of the nuclear pore complex?

Answer 8

Controls movement in and out of the nucleus.

Question 9

What is transferred out of the nucleus via the nuclear pore complex?

Answer 9

mRNA, tRNA and ribosomal subunits

Question 10

What is transferred into the cell via the nuclear pore complex?

Answer 10

Control signals, RNA building blocks, energy

Question 11

What is the function of the control signals in the nucleus?

Answer 11

They control when genes are turned ‘off’ or ‘on.’

Question 12

What lines the inner surface of the nuclear envelope?

Answer 12

Nuclear lamina

Question 13

What is the structure of the nuclear lamina?

Answer 13

Made up of intermediate filaments, consisting of the protein lamin

Question 14

What are the two key functions of the nuclear lamina?

Answer 14

Maintain nucleus shape, organise DNA packing

Question 15

What does the nuclear pore complex consists of?

Answer 15

Nuclear pores, that span the entire double memnrane length

Question 16

What are nuclear pores made of

Answer 16

Nucleoporin

Question 17

How mnay nuclear pores per cell

Answer 17

~1000

Question 18

What is the function of the nucleolus

Answer 18

Produces ribosomal RNA and ribosomal sununits

Question 19

What is the diameter of a DNA double helix strand?

Answer 19

2nm

Question 20

What histones are used to form nucleosomes?

Answer 20

H2-H4

Question 21

What is a nucleosome and how are they formed?

Answer 21

A ‘bead’ consisting of a section of DNA that is wrapped around a core of proteins
(eight histones).

Question 22

What is the diameter of the fibre formed from the winding of DNA to form nucleoosmes

Answer 22

10nm

Question 23

After the 10nm fibre what is formed?

Answer 23

10nm nucleosomes interact with H1 histones, to form coils with a 30nm diameter.

Question 24

What is chromatin?

Answer 24

A 300nm diameter fibre made up of loops of 30nm fibre.

Question 25

What happens to chromatin fibres during the metaphase of cell division?

Answer 25

They form chromosomes.

Question 26

Write the summary diameters at everystage of DNA coiling.

Answer 26

2 10 30 300 - nm

Question 27

What do the 300nm fibres coil to form and when does this occur.

Answer 27

During cell diviison, 300nm coils to form metaphase chromosomes

Question 28

Create the summary list

Answer 28

2-10-30-300-MC

Question 29

What is a karyotype?

Answer 29

A representation of the chromosomes of each cell, which are normally arranged randomly within the cell.

Question 30

What are the less dense areas of the nucleus?

Answer 30

Euchromatin

Question 31

What are the dense areas of the nucleus?

Answer 31

Heterochromatin

Question 32

What is the function of euchromatin?

Answer 32

Allow genes currently being used to be easily accessible, by packing DNA less densely.

Question 33

What is the function of the heterochromatin?

Answer 33

Genes that are not currently in use are packed tightly so they are inaccessible.

Question 34

How can the relationship between euchromatin and heterochromatin be described?

Answer 34

Dynamic