3.2.2 Mitosis, Cell cycle,cancer

Question 1

What is mitosis?

Answer 1

Cell division where the cell divides to produce two genetically identical daughter cells

Question 2

What are the 4 stages of mitosis?

Answer 2

• prophase
• metaphase
• Anaphase
• Telophase

Question 3

What happens during interphase?

Answer 3

Takes place before mitosis
- cells make copies of their chromosomes by DNA replication
(only stage where DNA in nucleus doubles)

Question 4

What happens during prophase?

Answer 4

1) chromosomes condense (short and fat)
2) Nuclear envelope disappears
3) Spindle fibres form

Question 5

What happens during metaphase?

Answer 5

1) chromosomes line up along the centre of spindle

2) Spindle fibres attach to the centromeres of the chromosome

Question 6

What happens during Anaphase?

Answer 6

Chromatids are pulled to opposite poles

Question 7

What happens during telophase?

Answer 7

1) two sets of chromosomes form new nuclei
2) Chromosomes become long and thin (not visible)
3) Nuclear envelope form around nuclei

Question 8

What is cytokinesis?

Answer 8

Divison of the cytoplasm

takes place after telophase

Question 9

calculation of mitotic index

Answer 9

number of cells with visible chromosomes / total cells

Question 10

Explain root tip procedure (RP 2)

Answer 10

1) add 10ml of HCL
2) place 2cm of root tip in acid and leave for 15 mins
3) set up microscope
4) Rinse root tip with distilled water inside of a watch glass
5) cut of 1mm of root tip and place on glass slide
6) cover in blue stain and macerate with mounted needle until thin and all cells are stained.
7) add slip cover and press over with ur finger and filter paper to absorb excess stain and make it as thin as possible.
8) Record what you see in a table
9) calculate mitotic index using your results

Question 11

Why is the root tip left in acid?

Answer 11

To break up tissues with individual cells

Question 12

What effect will maceration and pressing slide cover have?

Answer 12

makes the sample as thin as possible, allowing light through.
seperates cells

Question 13

What is the purpose of the stain?

Answer 13

stain binds to chromosomes so it can be seen more clearly

Question 14

Explain the cell cycle

Answer 14

• G1- interphase (orangelles and proteins made)
• S phase/DNA replication
• G2- interphase (proteins made)
• Mitosis
• cytokineses

Question 15

What is cancer?

Answer 15

a tumour that invades surrounding tissues

formed by uncontrollable cell division due to mutations in a gene

Question 16

Drugs that stop cell cycle

Answer 16

Can’t distinguish normal body cells and cancerous cells. so they also kill body cells that are dividing as well as the tumour.

Question 17

Drugs for cancer (G1, growth and protein production)

Answer 17

chemical drugs (chemo) prevents synthesis of enzymes needed for DNA replication
cell is unable to enter s phase ( DNA unable to replicate)

Question 18

Drugs for cancer (S phase, DNA replication)

Answer 18

Radiation and some drugs damage DNA.

cell is checked several times in cell cycle, if damaged it will kill itself- preventing tumour growth

Question 19

What is binary fission?

Answer 19

cell division in bacteria

Question 20

process of binary fission

Answer 20

• replication of circular DNA and plasmids

- division of cytoplasm. (produces 2 daughter cells with a single copy of circular DNA and variable copies of plasmids)

Question 21

How do viruses replicate?

Answer 21

Do not undergo cell division

Inject their nucleic acid into host cell, infected host cell replicates the virus particles.