Cell division

Question 1

Why cells divide?

Answer 1

Cells must divide repeatedly for an embryo to develop or for you to grow.

Cells also divide in order to replace damaged or worn out cells.

Question 2

Interphase

Answer 2

Interphase is the stage when the cell mostly performs its everyday functions.

Question 3

G1

Answer 3

The first growth phase (G1): the cell doubles in size and doubles the number of organelles

Question 4

S

Answer 4

The synthesis phase (S): An identical copy of all the cell’s DNA is made. This ensures that each new cell has a set of genetic material identical to that of the parental cell. This process is called DNA replication.

Question 5

G2

Answer 5

The second growth phase (G2): Proteins are synthesized that will help the cell divide. At the end of interphase, the cell is ready to enter mitosis.

Question 6

Centromere

Answer 6

The point where the two chromatids touch and where the microtubules attach.

Question 7

Chromatid

Answer 7

One of two identical parts of the chromosome.

Question 8

Mitotic phases

Answer 8

Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

Question 9

1. Interphase

Answer 9

Cell grow, making new proteins and organelles.

DNA replication takes place. Each chromosome replicates to form two sister chromatids joined by a centromere.

Centrioles are also replicated

Question 10

2. Prophase

Answer 10

The nucleus is still present

Chromatin condenses and thickens to form chromosomes.

Spindle fibres start to form

Question 11

3. Metaphase

Answer 11

The chromosomes line up across the centre of the cell.

Each chromosome is connected to spindle fibres by the centromere.

The nucleus is disassembled.

Question 12

4. Anaphase

Answer 12

The sister chromatids are pulled apart by spindle fibres.

The chromosomes move to the poles on opposite sides of the cell.

Question 13

5. Telophase

Answer 13

The chromosomes gather at opposite ends of the cell.

The chromosomes lose their distinct shape again to form threads of chromatin.

Two new nuclei begin to form.

Question 14

6. Cytokinesis

Answer 14

The cytoplasm pinches in hald to split forming two completely distinct daughter cells.

Each daughter cell has an identical set of duplicate chromosomes.

This stage can happen following mitosis or overlap with other stages.

Question 15

What does each daughter cell recieve?

Answer 15

During mitosis, each daughter cell recieves one copy of each chromosome.

Question 16

Prophase

Answer 16

The chromatin, which is unwound DNA, condenses forming chromosomes. The DNA becomes so tightly wound that you can see them under a microscope. The membrane around the nucleus, called the nuclear envelope, dissapears. Spindles also form and attatch to chromosomes to help them move.

Question 17

Metaphase

Answer 17

The chromosomes line up in the center of the cell. The chromosomes line up in a row, one on top of the next.

Question 18

Anaphase

Answer 18

The two sister chromatids of each chromosome separate as the spindles pull the chromatids apart, resulting in two sets of identical chromosomes.

Question 19

Telophase

Answer 19

The spindle dissolves and nuclear envelopes form around the chromosomes in both cells.