Unit 3 - Mitosis

Question 1

List the 2 main stages of a cell’s life

Answer 1

• Interphase

* Mitosis

Question 2

What happens during the interphase?

Answer 2

The interphase is the non-dividing stage of a cell’s life in which it prepares for mitosis, the dividing stage.

Question 3

List the 3 sub-stages of the interphase

Answer 3

1. G1- Growth stage 1
2. S - Synthesis stage
3. G2 - Growth stage 2

Question 4

What occurs during the sub-stages of the interphase?

Answer 4

1. G1- cells grow and replicate organelles
2. S - DNA is replicated and DNA associated proteins are synthesised
3. G2 - Mitotic proteins are synthesised

Question 5

Define ploidy

Answer 5

Refers to the number of pairs of chromosomes in the cell

Question 6

What is the difference between haploid and diploid cells?

Answer 6

Haploid cells have 1 copy of each chromosome each. They are denoted as ‘n’
Diploid cells have 2 copies of each chromosome each. They are denoted as ‘2n’

Question 7

What are the 2 main processes that occur during the mitosis phase of a cell’s life?

Answer 7

1. Mitosis - nuclear division

2. Cytokynesis - cytoplasmic division

Question 8

List the 4 phases of mitosis

Answer 8

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase (wherein cytoplasm takes place)

Question 9

Define chromosomes

Answer 9

A DNA molecule containing most or all of the organism’s genetic material.

Question 10

Define chromatids

Answer 10

One half of a replicated chromosome. A pair of these will join at a centromere.

Question 11

What is the function of centrosomes in mitosis?

Answer 11

The cell organelle, centrosomes, contain centrioles which are a direct factor influencing cell division.

Question 12

What is the kinetochore of a chromosome?

Answer 12

A protein structure that serves to allow sister chromatids to be separated during cell division.

Question 13

What occurs during the mitotic Prophase?

Answer 13

• Chromosomes condense
• The nuclear membrane and nucleolus disappear
• Spindle fibres form
• Chromosomes are captured by spindle fibres

Question 14

What occurs during the mitotic Metaphase?

Answer 14

Centrioles polarise and align the chromosomes on the cellular equator with one kinetochore facing each pole.

Question 15

What occurs during the mitotic Anaphase?

Answer 15

• Sister chromatids separate

* Spindle fibres contract and pull chromatids poleward

Question 16

What occurs during the mitotic Telophase?

Answer 16

• Spindle fibres disintegrate
• Nuclear envelope form around both groups of chromosomes
• Chromosomes revert to their extended state
• Nucleoli reappear
• Cytokynesis takes place

Question 17

What occurs during the Cytokynetic phase in animals?

Answer 17

• Microfilaments attached to the cell’s plasma membrane form a ring around the cellular equator
• The ring contracts, dividing the cytoplasm in two, enclosing the daughter nuclei in separate cells

Question 18

What occurs during the Cytokynetic phase in plants?

Answer 18

• Takes place through the cell plate

* The cell plate will become a new cell wall between two cells.