Module 1.3: Cell Cycle & Cell Division

Question 1

Identify each stage of Interphase.

Answer 1

0. G0 phase
1. G1 phase
2. S phase (Synthesis)
3. G2 phase

Question 2

Identify the two stages of M Phase.

Answer 2

1. Karyokinesis (nuclear division)
2. Cytokinesis

Question 3

What occurs during the G0 phase?

Answer 3

• Cells stop actively dividing
• Two fates: They re-enter cell cycle after the issue is resolved OR they are permanently arrested (for highly differentiated cells)

Question 4

Describe the action of chromosomes during each stage of Mitosis.

Answer 4

Prophase: Chromatin condenses / supercoils with histones into chromosomes
Metaphase: Chromosomes align along the equator of the cell
Anaphase: Sister chromatids are separated via the contraction of micro spindle fibers
Telophase: Re-formation of nuclear membrane surrounding the recently separated chromosomes

Question 5

Differentiate between centromere, centrioles, and centrosomes.

Answer 5

Centromere: Site of linkage between two sister chromatids of a chromosome
Centrioles: Microtubule unit that forms the centrosome
Centrosomes: Organelle responsible for the formation of the spindle fiber apparatus

Question 6

Differentiate Spindle Fibers and Microtubules.

Answer 6

Microtubule: Long protein fibres that protrude from the centriole
Spindle Fibers: Aggregations of microtubules that are responsible for moving the chromosomes during cell division

Question 7

Define the Kinetechore

Answer 7

Site of spindle fiber attachment on the chromosome

Question 8

TRUE or FALSE. Centrosomes duplicate during the S phase.

Answer 8

TRUE

Question 9

Identify key differences between MEIOSIS and MITOSIS.

Answer 9

1. Number of daughter cells: 2 vs 4
2. Similarity of daughter cells: identical vs unique
3. Chromosome number: Diploid vs Haploid
4. Number of divisions: 1 vs 2
5. Somatic vs Gametes
6. Division: Equational Division vs Reductional Division

Question 10

Describe what occurs during Prophase I

Answer 10

• Pairing of homologous chromosomes
• Synapsis: site of DNA exchange between homologous pairs of chromosomes
• Crossing over: DNA exchange between homologous pairs of chromosomes
• Recombinant DNA is formed

Question 11

Differentiate between Bivalent and Tetrad

Answer 11

Tetrad: Refers to the 4 sister chromatids of found within a homologous pair
Bivalent: Refers to a pair of homologous chromosomes
**Terms are used synonymously though