Mitosis and meiosis

Question 1

What are homologous chromosomes?

Answer 1

A set of one maternal and one paternal chromosome

Question 2

What are the 3 main stages of the cell cycle?

Answer 2

Interphase, mitosis, cytokinesis

Question 3

What are the 4 stages of mitosis?

Answer 3

PMAT

Prophase
Metaphase
Anaphase
Telophase

Question 4

What happens during interphase?

Answer 4

DNA/organelle replication, protein synthesis, chromosomes aren’t visible

Question 5

Why does DNA replication need to happen before mitosis?

Answer 5

There needs to be 2 sets of information for both daughter cells that will be produced

Question 6

Why is mitosis important?

Answer 6

• Tissue growth/repair
• Production of genetically identical daughter cells
• Growth of zygotes

Question 7

What happens during prophase?

Answer 7

Chromosomes condense (visible), nuclear membrane breaks down, centrioles move to poles, spindle fibres form

Question 8

What happens during metaphase?

Answer 8

Spindle fibres attach to centromeres and move sister chromatids to the equator

Question 9

What happens during anaphase?

Answer 9

Spindle fibres contract, centromeres divide (forms 2 separate sister chromatids), sister chromatids pulled apart to opposite poles, identical chromosomes at each pole

Question 10

What happens during telophase?

Answer 10

Sister chromatids have reached poles, spindle fibres break down, new nuclear membrane forms around each group of chromosomes, chromosomes uncondense

Question 11

What is a tumour?

Answer 11

Large mass of cells produced by uncontrollable cell division

Question 12

How does chemotherapy treat cancer?

Answer 12

Interferes with interphase - prevents synthesis of enzymes needed for DNA replication

Question 13

How do prokaryotes replicate?

Answer 13

Binary fission

1. DNA/plasmids replicate
2. Cell gets bigger
3. DNA/plasmids move to opposite poles
4. Cytoplasm divides
5. New cell wall forms

Daughter cells have 1 copy of circular DNA and variable copies of plasmid DNA

Question 14

How do viruses replicate?

Answer 14

1. Host cell specific to attachment proteins
2. DNA/RNA injected into host cell
3. Host cell uses own ribosomes/enzymes to replicate viruses
4. Viruses released from host cell

Question 15

What is chromosome non-disjunction?

Answer 15

Homologous chromosomes/sister chromatids aren’t separated during meiosis

Question 16

What is the result of chromosome non-disjunction?

Answer 16

One gamete will have an extra chromosome, one gamete will have one less chromosome

Question 17

Haploid and diploid definition

Answer 17

Haploid (n) = contains 1 copy of each chromosome

Diploid (2n) = contains 2 copies of each chromosome

Question 18

What happens during meiosis I?

Answer 18

Centromere DOESNT split, homologous pairs are separated

Question 19

What happens during meiosis II?

Answer 19

Centromere splits, sister chromatids separated

Question 20

Crossing over definition

Answer 20

Pieces of DNA are exchanged between a bivalent to form a chasma chiasmata

Question 21

What is the result of crossing over?

Answer 21

2 daughter cells will have recombiant chromosomes, 2 daughter cells will have non-recombiant chromosomes

Question 22

What happens during independent segregation?

Answer 22

2 possibilities, 1 is random

Question 23

What process is n –> n or 2n –> 2n?

Answer 23

Mitosis

Question 24

What process is 2n –> n?

Answer 24

Meiosis

Question 25

What process is n –> 2n?

Answer 25

Fertilisation

Question 26

What are the 5 differences between mitosis and meiosis?

Answer 26

Mitosis
*Results in diploid daughter cells
*Homologous chromosomes don’t pair
*No crossing over of chromosomes
*1 division, 2 daughter cells produced
*Genetically identical cells produced

Meiosis
*Results in haploid daughter cells
*Homologous chromosomes associate in pairs
*Crossing over of homologous chromosomes
*2 divisions, 4 daughter cells produced
*Genetically different daughter cells produced

Question 27

Are interphase, DNA replication, end of meiosis I and end of meiosis II haploid or diploid?

Answer 27

Interphase: diploid
DNA replication: diploid
End of meiosis I: haploid
End of meiosis II: haploid