Cell Division

Question 1

What are the phases of the cell cycle?

4

Answer 1

1. G1 phase
2. S (Synthesis) phase
3. G2 phase
4. Mitosis phase
5. Cytokinesis

(S)ynthesis, (M)itosis

Question 2

What are the phases of mitosis?

(4)

Answer 2

1. Prophase
2. Metaphase
3. Anaphase
4. Telephase

Question 3

What happens during the G1phase?

(Gap 1)

(3)

Answer 3

1. Protein synthesis at a rapid rate
2. Metabolic reactions in cytoplasm
3. Rapid growth

Question 4

What happens during the S phase?

(Synthesis)

(1)

Answer 4

Replication of DNA in the nucleus

Question 5

What happens during G2 phase?

(Gap 2)

(3)

Answer 5

1. # of organelles increases
2. chromatin begins to condense into chromosomes
3. Microtubules begin to form

Second growth

Question 6

What is Mitosis?

(1)

Answer 6

When a nucleus divides into two genetically identical sister nuclei

Question 7

What happens during prophase?

First stage of mitosis

Answer 7

1. Chromatin becomes supercoiled
2. Mitotic spindle begins to form
3. Centromeres attach to the spindle
4. Centrosomes move to opposite poles of cell
5. Nuclear membrane desintigrates

Question 8

What happens during metaphase?

Second stage of mitosis

(1)

Answer 8

• Chromosomes move to metaphase plate(Centrosomes are now at opposite ends)

Question 9

What happens during anaphase?

Third stage of mitosis

(2)

Answer 9

1. Sister chromatids split
2. The resulting 2 chromosomes move towards the poles

movement of chromosomes is due to shortening of microtubules of spindle

Question 10

What happens during telophase?

Fourth stage of mitosis

(4)

Answer 10

1. Chromosomes are at each pole
2. Nuclear membrane and nucleoli reappear
3. Mitotic spindle disappears
4. Chromosomes uncoil

Question 11

What happens during Cytokinesis?

The last phase of cell division

(3)

Answer 11

1. Inward pinching of cell membrane causing cleavage furrow that separates the two daughter cells (animal cells)
2. Cell plate formation (plant cells)
3. The daughter cells now have genetically identical nuclei

Question 12

Explain cell plate formation in plant cells

Cytokinesis

(3)

Answer 12

1. Vesicles move to equator forming two membranes
2. Middle lamella is formed through the pectin and cellulose deposited between the membranes
3. The daughter cells remain attached

Question 13

What happens to chromosomes during the S phase?

(DNA)

(3)

Answer 13

1. DNA chromatin replicates creating genetic material doubles
2. In the chromosome, sister chromatins are held together by the centromere
3. Sister chromatids will separate during the end of mitosis

Question 14

What happens to chromosomes during the G2 phase?

(DNA)

(2)

Answer 14

1. The chromatin is uncoiled, with histones, and not visible
2. Chromatin begins to supercoil into chromosomes

chromosomes are visible

Question 15

What are cancer cells?

(1)

Answer 15

Cells that have lost control of division and divide uncontrollably

Question 16

What are cyclins?

(What do they do?)

Answer 16

Proteins that control the cell going through the cell cycle

Question 17

How do cyclins control the cell’s cell cycle?

Answer 17

1. There are four cyclins trigger different stages
2. Cyclins bind to CDK’s and activate them
3. CDK’s phosphorylate other proteins that perform specific functions in the cell cycle

CDK: Cyclin dependent kinases

Question 18

Why could cyclins be a potential cancer treatment?

Answer 18

If the cyclins of cancer cells could be specifically targetted it could be possible to interrupt the cancerous cell’s cell cycle and kill it