Unit 2 - Mitosis & Cell cycle

Question 1

Describe how Eukaryotic cells divide

AND purpose of mitosis.

Answer 1

• Through cell cycle and divide by mitosis
  Mitosis
• Produces 2 identical daughter cells from parent cell
• Allows for cell growth and replacement

Question 2

Describe the stages in the cell cycle

Answer 2

1. Interphase
   - Longest stage in cell cycle
   G1 - Cell grows & synthesise proteins for replication
   S - DNA replication
   G2 - Organelles replicated e,g mitochondria
2. MITOSIS/MEIOSIS 10%
   - Creating 2 identical diploid cells with the same parent DNA
3. Cytokinesis
   - Division of cyptoplasm

Question 3

Describe the interphase stage

not part of mitosis

Answer 3

Interphase
- Longest stage in cell cycle
G1 - Cell grows & synthesise proteins for replication
S - DNA replication
G2 - Organelles replicated e,g mitochondria

Question 4

Describe the Prophase stage of MITOSIS.

PMAT.

Answer 4

• Chromosomes condense & become visible
• Centrioles separate to move to opposite poles of the cell to form mitotic spindle fibres
• Nuclear envelope & nucleolus break down

Question 5

Describe the Metaphase stage of MITOSIS.

Answer 5

• Sister chromatids line up along the equator of the cell
• Spindle fibres released from poles attach to chromatids by centromere

Question 6

Describe the Anaphase stage of MITOSIS.

Answer 6

STAGE REQUIRES ATP provided by respiration

• Centromere divides separating sister chromatids
• Spindle fibres contract and chromosomes (no longer chromatids) pulled to opposite poles
• Spindle fibres break down

Question 7

Describe the Telophase stage of MITOSIS.

Answer 7

• Chromosomes at each pole become long and thin again becoming invisible again
• Cytoplasm splits(CYTOKYNESIS) and nuclear envelopes form around each group of chromosomes
• 2 daughter cells created which are genetically identical

Question 8

Describe how prokaryotic cells replicate.

Answer 8

Binary fission.

• Replication of DNA and plasmids
• Division of cytoplasm to produce 2 daughter cells
• Each with a single copy of circular DNA but a variable number of plasmids

Question 9

Describe why viruses do not undergo cell division

BUT how they replicate

Answer 9

• Viruses are non-living so do not undergo cell division
• Instead, inject nucleic acid into the host
• & Infected host cell replicates the viral particles

Question 10

Describe what type of process Mitosis and result of mitosis not properly controlled.

Answer 10

• Mitosis is a controlled proces, cell cycle can be increased leagding perhaps to:
• Uncontrolled cell division can lead to the formation of tumors and cancers

Question 11

Describe the role of cancer treatments.

Answer 11

Controlling cell division by:

• Preventing DNA replication
• Disrupting cell cycle

Question 12

Describe the calculation for the mitotic index.

Answer 12

number of cells in mitosis/ total number of cells TIMES 100

Question 13

What is a homologous pair of chromosomes,

Answer 13

• Two chromosomes that carry the same genes