1.5

Question 1

What is the function of the cytoskeleton?

Answer 1

Gives mechanical support and shape to cells and consists of different protein structures.

Question 2

What is the structure of microtubules?

Answer 2

Protein structures and are hollow cylinders composed of tubulin

Question 3

Where do microtubules radiate from?

Answer 3

The MTOC (microtubules organising centre) aka the centrosome

Question 4

The formation and breakdown of microtubules involved…

Answer 4

Polymerisation and depolymerisation

Question 5

What does cell division allow?

Answer 5

Allows organisms to grow, develop, replace dead cells and so repair tissues

Question 6

What does the length of the cell cycle depend on?

Answer 6

Type of cell and external factors.

Question 7

What are the two main phases of the cell cycle?

Answer 7

Interphase and Mitotic phase with cytokinesis

Question 8

What does interphase include?

Answer 8

G1, S and G2

Question 9

What does the M phase consist of?

Answer 9

Prophase, metaphase, anaphase and telophase.

Question 10

What is cytokinesis?

Answer 10

When the two daughter cells are formed after cytoplasmic division

Question 11

What happens in prophase?

Answer 11

Nuclear envelope breaks down and spindle microtubules attach to chromosomes.

Question 12

What happens in metaphase?

Answer 12

Chromosomes aligned on the metaphase plate

Question 13

What happens in anaphase?

Answer 13

Chromosomes are pulled to opposite sides by shortening microtubules

Question 14

What happens in telophase?

Answer 14

Nuclear envelopes form round condensed chromosomes

Question 15

Why are checkpoints required?

Answer 15

They are used to assess the cell’s condition during the cell cycle. Progression to the next phase will be halted until certain requirements are met.

Question 16

Where are the checkpoints?

Answer 16

Near the end of G1, at the end of G2 and the metaphase of the M phase.

Question 17

What do cyclins do?

Answer 17

Accumulate during cell growth and are involved with regulating the cell cycle

Question 18

What do cyclins do with CDKs?

Answer 18

They combine with and activate them turning into cyclin CDKs. These complexes phosphorylase proteins that regulate protein.

Question 19

What does CDK stand for?

Answer 19

Cyclin dependent kinases

Question 20

If sufficient phosphorylation….

Answer 20

Progression ovcurs

Question 21

If insufficient phosphorylation….

Answer 21

Stop

Question 22

What happens at the G1 checkpoint?

Answer 22

Phosphorylation by G1 cyclinCDK inhibits Rb thus transcription of genes that code for the proteins needed for DNA replication takes place.

Question 23

What is Rb?

Answer 23

Retinoblastoma protein is a tumour suppressor as it inhibits gene transcription coding for proteins needed for DNA replication.

Question 24

What happens at the G2 checkpoint?

Answer 24

Any damage to DNA is assessed and if there is DNA damage this triggers the activation of the p53 protein.

Question 25

What does activation of p53 do?

Answer 25

Either; 1. Stimulation of DNA repair 2. Arrest the cell cycle 3. Initiate cell death (apoptosis)

Question 26

What does the M checkoint control?

Answer 26

Progression from metaphase to anaphase

Question 27

What is progression conditional on in the M checkpoint?

Answer 27

The chromosomes being correctly aligned on the equator and attached to the spindle microtubules.

Question 28

What causes a degenerative disease?

Answer 28

uncontrolled cell death

Question 29

What causes a tumour?

Answer 29

uncontrolled cell cycle

Question 30

What is a proto-oncogene?

Answer 30

a normal gene involved in the control of cell growth or division.

Question 31

What can proto-oncogenes mutate to form and what happens next?

Answer 31

Tumour-promoting oncogene resulting in uncontrolled cell division

Question 32

What is apoptosis?

Answer 32

A normal, genetically regulated process leading to the death of cells and triggered by the presence or absence of certain stimuli, as DNA damage

Question 33

What is an example of an internal death signal?

Answer 33

DNA damage

Question 34

What is activated due to DNA damage?

Answer 34

p53 tumour suppressor protein

Question 35

What is activated due to DNA damage?

Answer 35

p53 tumor suppressor protein

Question 36

What do external death signals do?

Answer 36

These molecules bind to a surface receptor protein triggering a protein cascade within the cytoplasm

Question 37

What do internal and external signals end in?

Answer 37

The production of active caspases that cause the destruction of the cell.

Question 38

Why is apoptosis important?

Answer 38

Remove cells during development that are no longer required as development progresses or during metamorphosis eg between fingers and toes.