Mitosis and Meiosis

Question 1

Why is mitosis important?

Answer 1

• we wont grow or heal with out cell division

Question 2

What are the 4 stages of Mitosis?

Answer 2

Prophase, Metaphase, Anaphase, Telophase (PMAT)

Question 3

Explain what happens in Prophase

Answer 3

The chromatin (DNA and proteins) condenses into visible chromosomes, each consisting of two sister chromatids joined together at a centromere
There are 46 chromosomes, with 92 chromatids
The nuclear membrane begins to break down, and the mitotic spindle starts to form

Question 4

Explain what happens in Metaphase (middle)

Answer 4

The chromosomes align in the middle, and the spindle fibres attach to the centromere of each chromosome
The nucleus is no longer there
46 chromosomes, 92 chromatids

Question 5

Explain what happens in Anaphase (away)

Answer 5

The spindle fibres shorten, pulling the sister chromatids apart toward the opposite poles of the cell, separating the chromatids and splitting them back into their individual chromosomes
Split at the centromere, resulting in 92 chromosomes and 92 chromatids
This separation ensures that each daughter cell will receive an identical set of chromosomes

Question 6

Explain what happens in Telophase (two)

Answer 6

The separated chromatids reach the cell poles, and a new nuclear membrane forms around each set of chromosomes
The chromosomes begin to decondense back into chromatin
Cleavage begins to form

Question 7

What is mitosis?

Answer 7

a type of cell division that results in two daughter cells, each having the same number and kind of chromosomes as the parent nucleus.

Question 8

What is Meiosis?

Answer 8

Meiosis is a specialised type of cell division that occurs to produce gametes. It reduces the chromosome number by half, resulting in four genetically diverse haploid cells (only containing a single set of chromosomes) from a single diploid cell.

Question 9

What is the gamete in females and males

Answer 9

Ova, sperm

Question 10

What are haploid cells?

Answer 10

This cell has one copy of every chromosome
Said to have ‘n’ chromosomes

Question 11

What are diploid cells

Answer 11

This cell has two of each chromosome, one from each parent
Said to have ‘2n’ chromosomes

Question 12

Explain what happens in Prophase 1

Answer 12

• Chromosomes condense and pair up with their homologous chromosomes (pairs of chromosomes that have the same structure and carry the same types of genes but may have different alleles, one comes from the mother and the other from the father) to form tetrads. This process is called synapsis.
• Crossing over (exchange of genetic material between homologous chromosomes) occurs, increasing genetic diversity. It is the recombination of alleles in homologous chromosomes.
• Crossing over results in genetic variation in gametes
• The nuclear envelope begins to break down

Question 13

Explain what happens in Metaphase 1

Answer 13

Tetrads align along the metaphase plate
Spindle fibres attach to the centromeres of each homologous pair

Question 14

Explain what happens in Anaphase 1

Answer 14

Homologous chromosomes are pulled apart to opposite poles of the cell, but sister chromatids remain attached at this stage

Question 15

Explain what happens in Telophase 1

Answer 15

• The separated homologous chromosomes reach the poles, and the nuclear membrane may reform
• The cell undergoes cytokinesis, resulting in two haploid daughter cells

Question 16

Explain what happens in Prophase 2

Answer 16

In each haploid cell, chromosomes condense again and the nuclear envelope breaks down

Question 17

Explain what happens in Metaphse 2

Answer 17

Chromosomes align along the metaphase plate, with spindle fibres attaching to the centromeres of sister chromatids

Question 18

Explain what happens in Anaphase 2

Answer 18

Sister chromatids are pulled apart and move to opposite poles of the cell

Question 19

Explain what happens in Telophase 2

Answer 19

Chromatids reach the poles, and the nuclear membrane reforms
Cytokinesis occurs, resulting in four genetically unique haploid cells

Question 20

Why do we need Meiosis?

Answer 20

• genetic variation
• formation of ganetes
• enhancing adaptability of a population