The cell cycle

Question 1

Name the 2 phases of the cell cycle

Answer 1

Interphase and the mitotic phase

Question 2

What makes up interphase

Answer 2

G1, G0, S phase and G2

Question 3

What makes up mitotic phase

Answer 3

Prophase, metaphase, anaphase, telophase, cytokinesis

Question 4

What is the longest part of the cell cycle

Answer 4

G1

Question 5

What is the shortest part of the cell cycle

Answer 5

mitotic phase

Question 6

Describe G1

Answer 6

• Genes involved in cell cycle progression are switched off so the cell cannot initiate a new round of initiation and cell proliferation.
• If there is a poor nutrient suplly/ if there are antiproliferative stimuli’s present, the cell cycle Is delayed and the cell will exit the cycle to the G0 phase
• If there is a good nutrient supply and positive proliferative stimuli, the cell will pass through the regulator off the cycle, resulting in DNA replication and cell division to occur

Question 7

Describe G0

Answer 7

• This is a highly regulated stage of the cell cycle
• In this stage, cells normally become differentiated to form specialised functions, and therefore no longer undergo cell division.

Question 8

Describe S phase

Answer 8

The pre-replication complex that forms during the G1 phase that ensures that DNA replication only occur once is dismantled, resulting in the formation of 2 sister chromatids. Thee 2 sister chromatids are linked by cohesion

Question 9

Describe G2

Answer 9

• Enzyme activity triggers the entry of the cell into the mitotic stage. A checkpoint is present here, and if un-replicated/damaged dna is detected, then the entry of the cell into the mitotic phase is delayed.

Question 10

Describe prophase

Answer 10

• This is where the chromosome condenses. The centromeres separate, forming the 2 poles of the spindle fibres.

Question 11

Describe metaphase

Answer 11

• Here the chromosome attaches to the spindle fibre at the pole of the cell.

Question 12

Describe anaphase

Answer 12

• 2 sister chromatids are separated by the spindle fibres separating and being pulled apart to different ends of the cells

Question 13

`Describe telophase

Answer 13

• The nuclear envelope reforms on the surface of the chromatin

Question 14

Describe cytokinesis

Answer 14

• The 2 newly formed daughter cells separate from one another

Question 15

Describe the g1 checkpoint

Answer 15

Check for DNA damage and favourable environmental conditons. Involves retinoblastmo

Question 16

Describe G2 checkpoint

Answer 16

Check for damaged and unreplicated DNA

Question 17

Describe mitotic checkpoint

Answer 17

Checks correct chromosomal attachment to spindle

Question 18

Describe cyclin dependent kinase role in cell cycle regulation

Answer 18

During g1, cyclin proteins accumulate. These combine with kinase to form CDKs.
CDKs cause phosphorylation of proteins that stimulate the cell cycle.
• Retinoblastoma (Rb) restricts progression from the g1 phase to s phase. Rb binds to a transcription factors
• When cell are about to enter the s phase, CDKs phosphorylate the Rb protein, inhibiting its activity so it can no longer bind to the transcription factor.
• Transcription factor released and transcripts genes that are require for dna replication, allowing cell to enter s phase.

Question 19

At what stage of the cell cycle does nuclear division occur

Answer 19

mitotic

Question 20

Name a characteristic that highlights malignant tumours metastatic ability

Answer 20

They can give rise to distant secondaries

Question 21

What does VEGF stimulate in tumours

Answer 21

stimulates the formation of a blood supply for tumour

Question 22

Define neoplasm

Answer 22

a new growth

Question 23

Define anaplastic

Answer 23

describes the undifferentiated appearance of malignant cells

Question 24

Define dyssplastic

Answer 24

containing abnormal cells or showing abnormal development.

Question 25

Define metaplastic

Answer 25

the reversible transformation of one differentiated cell type to another differentiated cell type

Question 26

What reactions do kinase enzymes catalyse

Answer 26

phosphorylation

Question 27

What prevents end to end chromosome fussion

Answer 27

telomeres

Question 28

What is the name of a tumour of the epithelial cells

Answer 28

carcinoma