3.2.2 All cells arise from other cells

Question 1

Define mitosis

Answer 1

Mitosis is the type of cell division which produces two daughter cells that are
identical from the parent cell

Question 2

Define meiosis

Answer 2

Meiosis is the type of cell division which produces daughter cells that is not
identical to the parent cell, and contains half the amount genetic material as the
parent cell

Question 3

Define interphase

Answer 3

Interphase is the stage in the cell cycle where biochemical processes occur to
prepare the cell for mitosis

Question 4

Describe the three stages of interphase

Answer 4

○ G1 phase is when cells grow in size and synthesise mRNA and proteins
needed for mitosis.
○ S phase follows the G1 phase and is when DNA replication occurs.
Chromosomes are replicated forming two sister chromatids each.
○ G2 phase follows the S phase and is when the cell continues to grow and
synthesise proteins needed for mitosis. It is during the G2 phase when most
microtubules, needed for mitosis are produced

Question 5

Describe prophase

Answer 5

During the prophase, the nuclear
membrane of the cell breaks down
forming small vesicles. In the
process, the nucleolus
disintegrates.
‒ The centrosome that have been
duplicated in the G2-phase
separates. They start to move
towards opposite poles of the cells.
‒ Mitotic spindles extend between
the centrosomes, pushing them
further apart when the microtubules
lengthen.
‒ Chromosomes become visible,
which is composed of two
chromatids joined together at the
centromere.

Question 6

Describe metaphase

Answer 6

‒ This is when the centromeres of the
chromosomes line up in an imaginary
line equidistant (at equal distances)
to the two centrosome poles called
the metaphase plate.
‒ This is facilitated by the counter
effect of the pull of the two opposing
kinetochore microtubules

Question 7

Describe anaphase

Answer 7

This is when the the centromere
splits, dividing the chromosome into
two sister chromatids.
‒ Each chromatid moves to opposite
poles of cells when the mitotic
spindle shortens.

Question 8

Describe telophase

Answer 8

The mitotic spindle disappears during telophase and the chromosomes uncoil to
form diffuse chromatin.
‒ A nuclear membrane forms around the daughter chromosomes present in both
ends of the cell.

Question 9

Describe cytokinesis

Answer 9

This is when physical separation of cytoplasmic materials occur in the parent cell.
‒ For animal cells, a cleavage furrow is produced by having the actin filaments pull
the equator of the cell inwards, forming the fissure called a cleavage furrow. The
cleavage furrow continually develops eventually dividing the cell in two.
‒ For plant cells, a cell plate is produced by having Golgi vesicles come together at
the position of the original metaphase plate separating the two sets of
chromosomes. The cell plate continually grows until it reach the cell walls. New
cell walls are then produced from the contents of the vesicle.