The Cell Cycle and Mitosis (2.1.6)

Question 1

What are the two roles of mitosis?

Answer 1

Growth of multicellular organisms

Repair of damaged tissues

Question 2

What three things occur during interphase?

Answer 2

DNA is unravelled and replicated

Organelles are replicated

ATP content is increased

Question 3

Lable the picture.

Answer 3

Question 4

What happens during Meiosis Prophase 1?

Answer 4

Chromosomes condense

• Homologous chromosomes pair up*
• Crossing over takes place*

Centrioles move to opposite ends forming (Protein) Spindle fibres

Nuclear envelope breaks down

Question 5

What happens during Prophase?

Answer 5

Chromosomes condense

Centrioles move to opposite ends forming (Protein) Spindle fibres

Nuclear envelope breaks down

Question 6

What happens during Meiosis Metaphase 1?

Answer 6

Homologous pairs line up across the spindle equator

Spindle fibres attach to centromeres

Metaphase checkpoint to ensure centromeres are attached

Question 7

What happens during Metaphase?

Answer 7

Chromosomes line up across the spindle equator

Spindle fibres attach to centromeres

Metaphase checkpoint to ensure centromeres are attached

Question 8

What happens during Meiosis Anaphase 1?

Answer 8

Spindles contract pulling the pairs apart

Question 9

What happens during Meiosis Telophase 1?

Answer 9

Nuclear envelope forms around the two groups of Chromosomes.

Cytokenesis occurs and two haploid daughter cells are produced.

Question 10

What happens during Telophase?

Answer 10

Chromatids uncoil and become long and thin again

Chromosomes again

Nuclear envelope forms around the two groups of Chromosomes forming two nuclei

Question 11

What happens during Cytokinesis?

Answer 11

Starts in Anophase > Ends in Telophase

Cytoplasm divides into two

In animal cells, a cleavage furrow forms.

Question 12

What happens during:

Gap phase 1

and

G1 Checkpoint

Answer 12

Gap phase 1

New organelles and proteins are made

Cell increases in size

G1 Checkpoint

Checks all necessary chemicals are present

Checks for any damage to DNA

Question 13

What happens during:

Gap phase 2

and

G2 Checkpoint

Answer 13

Gap phase 2

Cell continues to grow in size

Proteins required for cell division are made

G2 Checkpoint

Checks all DNA has been replicated and there are no errors

Question 14

What happens during S phase?

Answer 14

Synthesis

Cell replicates its DNA

Question 15

Normal body cells have a … of chromosomes.

Pairs of matching chromosomes are called … chromosomes.

Gametes have a … of chromosomes.

Answer 15

diploid number (2n)

homologous

haploid number (n)

Question 16

A sperm and an egg create a what?

Answer 16

Zygote

Question 17

Define meiosis.

Answer 17

Cell division

Reproductive organs

Produce gametes

Involves reduction division

Question 18

Define homologous chromosomes.

Answer 18

A matching pair of chromosomes

Same size, same genes

Or different versions of those genes (alleles)

Question 19

What is the result of Meiosis 2

Answer 19

Four unique haploid daughter cells are produced.

Question 20

How is genetic variation created in meiosis?

Answer 20

Through crossing-over, the swapping over of alleles. (Recombination)

Independent assortment of chromosomes

Question 21

Explain independent assortment.

Answer 21

When homologous pairs line up, it is completely random which chromosome from each pair ends up in which daughter cell.