Cells Alive 5: Cell Division

Question 1

What occurs during Interphase in cell divison?

Answer 1

The cell grows and the protein content doubles, the organelles double in size- in the S-phase DNA is synthesised, the centrosme repicaltes

Question 2

What si the first stage of metaphase?

Answer 2

Prophase

Question 3

What occurs during prometaphase?

Answer 3

1 Nuclear envelope breaks down…
…which allows microtubules access to
the chromosomes
2 Chromosomes attach to the
microtubules via kinetochore complex
(This interaction will pull the chromosome
apart during cell division)

Question 4

What occurs during Prophase?

Answer 4

1 Chromosomes condense
2 Mitotic spindle (microtubules and
associated proteins polymerise) forms
3 Centrosomes move apart
4 Protein complex (kinetochore) forms at
centromere of the chromosome (the bit
where the two arms meet)

Question 5

What occurs during Metaphase?

Answer 5

1 Chromosomes align at the equator
2 Sister chromatids attach to opposite poles
by kinetochore microtubules

Question 6

What occurs during Anaphase?

Answer 6

1 Cohesive link between sister chromatids is released
2 Kinetochore microtubules shorten
3 Centrosomes move apart
So the sister chromatids are pulled to opposite ends of the cell

Question 7

What occurs during Telophase?

Answer 7

1 Daughter chromosomes reach the poles
2 New nuclear envelope forms from fragments
attached to individual chromosomes
Therefore two nuclei
3 Contractile ring begins to form
around the equator

Question 8

What do the kinetochore microtubules do?

Answer 8

Attach to the chromosones

Question 9

What do teh mcirotubules do during prometaphase?

Answer 9

They grow and shrink as they try and find a target

Question 10

What do the microtubules do during metaphase?

Answer 10

motor proteins (+ & - ) pull
chromosomes around until they are aligned

Question 11

What occurs during anaphase?

Answer 11

kinetochore microtubules shorten &
motor proteins move the chromatids towards the
centrosome – actively separate the two chromatids –
genetic material is split in the two new cells

Question 12

How is actin involved with ctokinesis?

Answer 12

involved in ring contraction

Question 13

Where is the restriction point?

Answer 13

at the end of G1

Question 14

What is the purpose of the restriction point?

Answer 14

• growth factor interacts with cell surface receptor
• triggers intracellular signalling pathway
• activates a transcription factor called Myc
• turns on genes that promote entry into mitosis

Question 15

What is the kinetochore?

Answer 15

The protein complex at the centre of the chromosome

Question 16

What do the nuclear lamina need to do before mitosis?

Answer 16

They need to disassemble

Question 17

What do the kinetochore microtubules do during prometaphase?

Answer 17

grow and shrink until they can find a target

Question 18

What do the kinetochore microtubules do during metaphase?

Answer 18

motor proteins pull chromosomes around until they are aligned

Question 19

What do the kinetochore microtubules do during anaphase?

Answer 19

They shorten and motor proteins move the chromatids towards the centrosome

Question 20

What does Myc do?

Answer 20

Turns on genes that promote entry into mitosis

Question 21

what are cdk’s?

Answer 21

there are 4 classes of them, their activity oscillates during the cell cycle- phosphorylate proteins modulate major events in the cell cycle

Question 22

What are cyclins?

Answer 22

they bind and activate cdk’s

Question 23

What is leptotene?

Answer 23

The first stage of prophase 1 in meiosis, when the chromosomes condense

Question 24

What is zygotene?

Answer 24

The second stage of prophase 1 in meiosis, when the homologous chromosomes align

Question 25

What is pachytene?

Answer 25

The third stage of meiosis prophase 1, when the chromosomes cross over

Question 26

What is Diplotene?

Answer 26

The fourth stage of meiosis 1, synaptonemal complexes break
down; pairs of chromosomes linked at
crossover points (chiasmata)

Question 27

What is diakinesis?

Answer 27

The last stage of Prophase 1 in meiosis, the chromosomes condensation reaches a maximum