Cell division

Question 1

What are the 3 parts of interphase?

Answer 1

G1, S, G2

Question 2

What happens in G1?

Answer 2

Organelles replicate

Cell grows in size

Question 3

What happens in S?

Answer 3

DNA is replicated in the nucleus

Question 4

What happens in G2?

Answer 4

Energy stores are increased

Cell continues to grow in size

Question 5

What is checked at the G1 checkpoint?

Answer 5

• Cell size
• Nutrients
• Growth factors
• DNA damage

Question 6

What is checked at the G2 checkpoint?

Answer 6

• Cell size
• DNA replication
• DNA damage

Question 7

What is G0?

Answer 7

Where the cell leaves the cycle

Question 8

What are 3 common reasons why cells enter G0?

Answer 8

The cell has differentiated
The cell is old
The cell is damaged

Question 9

What are senescent cells?

Answer 9

Old cells that stop dividing

Question 10

What is cytokinesis?

Answer 10

Where the cytoplasm divides and two cells are produced

Question 11

What is the spindle assembly check point?

Answer 11

Where it is checked that all chromosomes are attached to spindle fibres and aligned

Question 12

What is the spindle assembly check point also known as?

Answer 12

The metaphase checkpoint

Question 13

What would the indefinite replication of cells lead to?

Answer 13

Increased frequency of mutation = increased likelihood of harmful mutation

Question 14

What does mitosis produce?

Answer 14

Two identical daughter cells

Question 15

How are chromatids produced?

Answer 15

When a chromosomes is converted into two identical chromatids

Question 16

What is the centromere?

Answer 16

The centre point where two chromatids join to form a chromosome

Question 17

What are the four stages of mitosis?

Answer 17

Prophase, Metaphase, Anaphase and Telophase

Question 18

What happens to the nucleolus during prophase?

Answer 18

It disappears

Question 19

What do chromatin fibers do during prophase?

Answer 19

Coil and condense to form chromosomes

Question 20

What happens in animal and but not plant cells during prophase to do with centrioles?

Answer 20

Centrioles move to opposite poles of the cell

Question 21

What has happened by the end of prophase?

Answer 21

The nuclear envelope has disappeared

Question 22

What happens during metaphase?

Answer 22

Chromosomes line up along the metaphase plate equator

Question 23

What is the metaphase plate?

Answer 23

The (invisible) line through the centre of the cell, where chromosomes line up (during metaphase)

Question 24

What happens during anaphase to centromeres?

Answer 24

Centromeres holding the chromatids together in each chromosomes divide

Question 25

What happens to chromatids in anaphase?

Answer 25

The chromatids are separated by the shortening of spindle fibres, and are pulled to opposite poles of the cell

Question 26

What happens during telophase?

Answer 26

Two new sets of chromosomes gather at each pole of the cell The nuclear envelope reforms around these two groups of chromosomes The chromosomes begin to uncoil and the nucleolus is formed

Question 27

What happens in cytokinesis in animal cells?

Answer 27

- Cleavage furrow forms around the middle of the cell | - Cytoskeleton pulls cell surface membrane inwards until it is close enough to fuse around the middle, forming two cells

Question 28

What happens in cytokinesis in plant cells?

Answer 28

Vesicles gather along the middle of the cell, and fuse with one another and the cell surface membrane to form two separate cells

Question 29

What are homologous chromosomes?

Answer 29

Chromosomes from different parents that are similar and pair up together

Question 30

Overview of meiosis 1

Answer 30

Reduction division- the pairs of homologous chromosomes are separated into two cells- each will contain 23 chromosomes

Question 31

Overview of meiosis 2

Answer 31

Similar to mitosis- the pairs of chromatids present in each cell are separated, forming two more cells (4 total overall)

Question 32

What is haploid?

Answer 32

A cell with 23 chromosomes

Question 33

What is the main thing that occurs in prophase 1 of meiosis?

Answer 33

Crossing over, where genes are swapped between homologous chromosomes

Question 34

What is formed from crossing over?

Answer 34

Bivalents

Question 35

What is the main thing that occurs in metaphase 1 of meiosis?

Answer 35

Homologous chromosomes line up in pairs along the metaphase plate- independent assortment occurs

Question 36

What is independent assortment?

Answer 36

The orientation and location of each homologous pair on the metaphase plate equator is random and independent of any other homologous pair, meaning there are many different combinations that can occur

Question 37

What does independent assortment and crossing over result in?

Answer 37

Genetic variation

Question 38

What are the main difference between anaphase 1 in meiosis and anaphase in mitosis?

Answer 38

In anaphase of mitosis, chromatids are pulled to opposite poles, whereas in meiosis 1, homologous chromosomes are pulled to opposite poles

Question 39

What happens in telephase 1 of meiosis?

Answer 39

The nuclear membrane reforms around the different sets of chromosomes The cell undergoes cytokinesis

Question 40

What are the 4 final products of meoisis?

Answer 40

4 non-identical daughter cells

Question 41

What is meiosis 2 very similar to?

Answer 41

Mitosis