2.6 Cell Division

Question 1

Name the 4 types of stem cells.

Answer 1

Unipotent
Multipotent
Pluripotent
Totipotent

Question 2

What are the sub-phases of interphase?

Answer 2

G0
G1
S
G2

Question 3

What are the 4 stages of mitosis?

Answer 3

Prophase
Metaphase
Anaphase
Telophase

Question 4

Describe prophase.

Answer 4

• the nuclear envelope breaks down
• sister chromatids joined at the centromeres shorten and condense
• centrioles move to the poles of the nucleus and spindle fibres start to form

Question 5

Describe metaphase.

Answer 5

-the chromatids line up at the equator of the nucleus and attach themselves to the spindle fibres

Question 6

Describe anaphase.

Answer 6

-the centromeres divide and the sister chromatids are pulled to opposite ends of the nucleus by motor proteins

Question 7

Describe telophase.

Answer 7

-the chromatids decondense and new nuclear envelopes form around the chromosomes creating two new nuclei

Question 8

Describe cytokinesis.

Answer 8

The division of the cytoplasm resulting in two identical daughter cells.

Question 9

What are unipotent stem cells?

Answer 9

Stem cells that can only develop into one type of cell.

Question 10

What are multipotent stem cells?

Answer 10

Stem cells that can develop into a few types of cells.

Question 11

What are pluripotent stem cells?

Answer 11

Stem cells that can develop into all cells apart from the placenta and embryo.

Question 12

What are totipotent stem cells?

Answer 12

Stem cells that can develop into all cells including the placenta and embryo.

Question 13

What happens at interphase?

Answer 13

Cells grow and replicate DNA and organelles. The cell is preparing to divide.

Question 14

Describe the G0 phase.

Answer 14

Where the cell is at rest if it has fully differentiated. There is also apoptosis for damaged cells which is programmed cell death.

Question 15

Describe the G1 phase.

Answer 15

The cell grows and synthesizes proteins.

Question 16

Describe the S phase.

Answer 16

The replication and synthesis of DNA. Once entering the S phase, the cell is committed to completing the cell cycle.

Question 17

Describe the G2 phase.

Answer 17

The organelles in the cell divides.

Question 18

Where are the two checkpoints in the cell cycle?

Answer 18

• between G1 and S

- between G2 and mitosis

Question 19

Describe what happens at the checkpoint between G1 and S.

Answer 19

The cell checks for DNA damage.

Question 20

Describe what happens at the checkpoint between G2 and M.

Answer 20

The cell checks the chromosomes have been replicated properly.

Question 21

What is mitosis?

Answer 21

A form of cell division that produces 2 genetically identical daughter cells called diploid cells.

Question 22

What is meiosis?

Answer 22

A form of cell division that produces 4 genetically different daughter cells called haploid gametes (sex cells) with half the normal number of chromosomes (23).

Question 23

What are homologous chromosomes?

Answer 23

A pair of chromosomes with genes at the same locus (1 maternal and 1 paternal)

Question 24

What are the two ways that cause genetic variation in meiosis?

Answer 24

Crossing over and independent assortment of chromosomes.

Question 25

Describe how crossing over causes variation.

Answer 25

Pairs of chromosomes line up and exchange their genetic material at prophase 1.

Question 26

Describe how independent assortment of chromosomes causes variation.

Answer 26

The random combination of homologous chromosomes at anaphase 2.

Question 27

What happens in meiosis 1?

Answer 27

Homologous chromosomes separate randomly as the cell divides in two. Each cell contains either a maternal or paternal copy of the homologous chromosomes.

Question 28

What happens in meiosis 2?

Answer 28

The independent segregation of sister chromatids before each cell divides again creating a total of 4 haploid gametes.