Mitosis and Cell cycle

Question 1

name the 3 reasons why mitosis is important

Answer 1

growth, differentiation, replacing damaged/old cells

Question 2

what is equation for the mitotic index

Answer 2

MI = no. of cells with condensed chromosomes/total no. of cells x100

Question 3

what is the longest phase of the cell cycle and how long (percentage) ?

Answer 3

interphase, 90%

Question 4

What happens in prophase?

Answer 4

chromatin condenses, spindle fibres form, chromosomes become visible

Question 5

What happens in metaphase?

Answer 5

spindle fibres (spindle apparatus) attach (from centrioles), chromosomes align, chromosomes made up of 2 chromatids

Question 6

What happens in Anaphase?

Answer 6

centromeres cleave by spindle fibres = chromatids separate to opposite poles of the cell

Question 7

What happens in telophase?

Answer 7

nuclear envelope forms, chromosomes unfold (large/thin) then disappearing. cytokinesis then occurs

Question 8

what is cytokinesis?

Answer 8

when the cytoplasm divides

Question 9

What happens in G1 of the cell cycle?

Answer 9

growth of cell

Question 10

What happens in S of the cell cycle?

Answer 10

synthesis of DNA (DNA replication)

Question 11

what happens in G2 of the cell cycle?

Answer 11

growth and final preparation of mitosis

Question 12

Bacteria cells divide by…..

Answer 12

binary fission

Question 13

How do bacteria cells divide (5 steps)

Answer 13

1. circular DNA replicates, copies attach to cell membrane
2. plasmids replicate
3. cytokinesis
4. cell wall forms
5. 2 daughter cells form

Question 14

how do viruses replicate? (4 steps)

Answer 14

1. attach to the host cell by attachment proteins
2. inject RNA into host cell
3. RNA provides instructions for virus to be produced
4. New virus released, cell continues to synthesise virus

Question 15

tumours are formed by ……

Answer 15

the uncontrolled cell division of mutated genes

Question 16

which is cancerous benign or malignant?

Answer 16

malignant

Question 17

can benign tumours invade other tissues or form secondary tumours?

Answer 17

no, only malignant ones

Question 18

what does metastases mean?

Answer 18

cancer cells moving to different parts of the body, causing secondary tumours

Question 19

how does metastases occur?

Answer 19

blood stream or lymphatic system

Question 20

when treating cancer how does disrupting cell division/cycle help?

Answer 20

• preventing DNA replication

- inhibiting metaphase: interfere with spindle formation

Question 21

Within multicellular organisms, not all cells retain the ability to…

Answer 21

divide

Question 22

Eukaryotic cells that do retain the ability to divide show…

Answer 22

a cell cycle

Question 23

G1, G2 and S are all part of which phase?

Answer 23

interphase

Question 24

how many daughter cells are produced after mitosis?

Answer 24

2 (genetically identical)

Question 25

chromosomes become visible in what stage?

Answer 25

prophase (initially long/thin threads then later shorten + thicken)

Question 26

What do chromosomes look like in metaphase?

Answer 26

made up of 2 chromatids joined by a centromere

Question 27

name the 3 stages of the cell cycle

Answer 27

interphase, nuclear division, cytokinesis