Cell Division

Question 1

How do unicellular organisms usually reproduce?

Answer 1

Through cell division, commonly binary fission.

Question 2

What do multicellular organisms depend on cell division for?

Answer 2

• Development from a fertilized cell
• Growth
• Repair

Question 3

How does cell division occur?

Answer 3

Mitosis and Meiosis.

Question 4

Chromosome

Answer 4

A string like structure structure comprised of DNA.

Question 5

Chromatin

Answer 5

DNA wrapped around histone proteins.

Question 6

Sister chromatid pair

Answer 6

Replicated DNA connected at the centresome, forming the x like structure.

Question 7

What are the 2 phases in the eukaryotic cell cycle?

Answer 7

Interphase (G1, S, and G2)
Mitotic Phase (M)

Question 8

What occurs during the M Phase of the eukaryotic cell cycle?

Answer 8

Mitosis, cytokensis (Division of cytoplasm)

Question 9

What occurs during the interphase stage of eukaryotic cell division?

Answer 9

G1 - Normal cell metobolism and growth
S - DNA replication occurs
G2 - Preparation for cell division

Question 10

What are the 5 stages of mitosis, in order?

Answer 10

1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telophase

Question 11

What happens in prophase?

Answer 11

DNA condenses to form chromatin in to sister chromatids, the centresome divides and microtubules begine to form the mitotic spindle.

Question 12

What happens in prometaphase?

Answer 12

Microtubules bind to the kinetechores (protein structures on chromosomes) anchoring them to the mitotic spindle.

Question 13

What happens in Metaphase?

Answer 13

The mitotic spindle organises the chromosomes into the middle of the cell.

Question 14

What happenes in Anaphase?

Answer 14

Microtubules pull the sister chromatids apart, this happens as the microtubules contract and expand to pull the chromatids to opposite ends of the cell.

Question 15

What happens in Telophase?

Answer 15

The two sets of chromosomes separated during anaphase are used to create new nuclei, the cell then splits in two via cytokenesis.

Question 16

What is Cytokenesis?

Answer 16

A pinching action separates the cytoplasm into 2 separate cells. In animals a cleavage furrow forms, in plants a cell plate forms.

Question 17

Why do liver cells divide?

Answer 17

In response to injury.

Question 18

Why do muscle cells divide?

Answer 18

Muscle cells do not divide, they repair themselves.

Question 19

What does the protein complex that regulates cell cycle consist of?

Answer 19

2 subunits:

• a regulatory subunit - termed cyclin
• A catalytic subunit (Cdk - cyclin dependant kinase) which only phosphoylates other proteins when bound to cyclin.

Question 20

What is MPF (Maturation-promoting factor)?

Answer 20

When cyclin binds to Cdk it forms a protein complex called MPF.

Question 21

If a Cdk-cyclin complex becomes more abundant in G2 phase and dissapears before G1 phase, what does this suggest?

Answer 21

The complex helps the cell move past the G2 phase.

Question 22

What are oncogenes?

Answer 22

Cells that actively promote cell division.

Question 23

What is the p53 gene?

Answer 23

A tumor supressor gene that prevents cells with damaged DNA from replicating.

Question 24

What are the three types of mutation that can lead to cancer?

Answer 24

• Translocation
• Transcription
• Gene deletion
• Point mutations