2.2 Cell Division

Question 1

In multicelluar organisms, can specialised cells divide

Answer 1

No

Question 2

What cells cannot divide

Answer 2

Specialised cells

Question 3

What occurs during G1 phase of the cell cycle

Answer 3

• Growth as cell increases in size
• New organelles made

Question 4

What occurs during S phase of the cell cycle

Answer 4

• DNA replication
• Chromatids produced
• Chromatids join at centromere to form a chromosome

Question 5

What occurs during the G2 phase of the cell cycle

Answer 5

• Growth as cell increases in size
• New organelles made

Question 6

What happens during the M phase of the cell cycle

Answer 6

Mitosis + Cytokenisis

Question 7

Describe what occurs in prophase of mitosis

Answer 7

• DNA coils and condenses to form visible chromosomes
• They are two sister chromatids joined at the centromere
• Spindle fibres begin to form

Question 8

Describe what occurs during metaphase of mitosis

Answer 8

• Chromosomes line up at the equator of the cell
• Spindle fibres attach to centromere

Question 9

Describe what occurs during anaphase of mitosis

Answer 9

• Chromosomes are pulled apart
• Centromere splits
• A chromatid from each pair is** pulled to opposite poles** of the cell
• As spindle fibres contract and shortern

Question 10

Describe what occurs during telophase of mitosis

Answer 10

• Chromosomes uncoil and uncondense
• Two diploid nuclei form at cell poles
• Spindle fibres break down

Question 11

Describe the process of cytokenisis in mitosis

Answer 11

• Cytoplasm divides
• 2 genetically identical daughter cells form

Question 12

What is the difference in the process of cancer cells dividing, and regualr cells dividing

Answer 12

Mitosis is a controlled process

Question 13

What ensures that DNA has been copied correctly during the cell cycle, and what happens if this fails

Answer 13

• Checks occur
• If they fail, uncontrolled cell division occurs
• Uncontrolled cell division can lead to tumours and cancer

Question 14

How to cancer treatments work

Answer 14

Slow the rate of cell division, or destroy rapidly dividing cells

Question 15

Describe the process of binary fission

Answer 15

• Circular DNA and plasmids are copied
• Cytoplasm divides
• 2 daughter cells are produced
• Each with a single copy of DNA and plasmids

Question 16

Why don’t viruses undergo cell division

Answer 16

They are non-living

Question 17

Describe the process of viral replication

Answer 17

• Attachement proteins on virus attach to cell receptors
• Virus injects nucleic acid into host cell
• Reverse transcriptase makes DNA from RNA
• The cell replicates the nucleic acids
• Cell produces viral proteins, capsids and enzymes
• The virus is assembled and released from the cell by budding of cell lysis

Question 18

RP2: Why roots placed in warm HCl

Answer 18

• Break down cell walls
• Stop mitosis

Question 19

RP2: Why end of root used

Answer 19

Where most mitosis is occuring

Question 20

RP2: Why squash sample, and why not too hard

Answer 20

• Thin layer of cells
• Allowing light to pass through
• Not pushed too hard, as to not break the chromosomes

Question 21

RP2: Why stain used

Answer 21

To distinguish chromosomes

Question 22

RP2: Why differnt mitotic indices obtained from different samples

Answer 22

• Roots different ages
• Different species of garlic
• Different parts of root tip
• Undergo mitosis at different rates