Mitosis and meiosis

Question 1

What are the phases of the cell cycle?

Answer 1

Interphase

Division

Question 2

What are the phases in interphase?

Answer 2

G1

S

G2

Question 3

What happens in the G1 phase?

Answer 3

Cell content is replicated

Question 4

What happens in the S phase?

Answer 4

DNA replication

Question 5

What happens in the G2 phase?

Answer 5

Cell and DNA repair

Question 6

When do the cell cycle checkpoints occur?

Answer 6

G1/S

G2/M

Question 7

What happens in the division phase?

Answer 7

Mitosis/meiosis

Question 8

What is the shape of a replicated chromosome?

Answer 8

X shape

Question 9

What are the two chromatids in a replicated chromosome called? Why?

Answer 9

Sister chromatids

because they’re identical

Question 10

What is each chromatid/chromosome made up of?

Answer 10

p arm

q arm

Question 11

How are the p and q arms told apart?

Answer 11

p arm is shorter

q arm is longer

Question 12

What are telomeres?

Answer 12

Repeated base sequence at each end of chromatid/chromosome

Question 13

What is the function of centromeres?

Answer 13

To hold together sister chromatids in a replicated chromosome

Question 14

What are centromeres made up of?

Answer 14

Repeated base sequences

Question 15

How are chromosomes classified based on the position of the centromere?

Answer 15

Metacentric

Submetacentric

Acrocentric

Telocentric

Question 16

What is the position of the centromere in metacentric chromosomes?

Answer 16

In the middle

p and q arm are same length

Question 17

What is the position of the centromere in submetacentric chromosome?

Answer 17

Upper half of the chromosome

p arm is shorter than q arm

Question 18

What is the position of the centromere in acrocentric chromosome?

Answer 18

Near the top of the chromosome

p arm is barely visible

Question 19

What is the position of the centromere in telocentric chromosome?

Answer 19

In the telomeres of the chromosome

no p arm

Question 20

Which human chromosomes are telocentric?

Answer 20

None of them!

Question 21

What is mitosis?

Answer 21

A type of cell division

Question 22

What type of cells undergo mitosis?

Answer 22

Somatic cells

Question 23

What does mitosis produce?

Answer 23

Two daughter cells

completely identical to each other and the parent cell

Question 24

Which tissues undergo a lot of mitosis?

Answer 24

Epidermis

Mucous membranes

Bone marrow

Spermatogonia

Question 25

What are the phases of mitosis?

Answer 25

Prophase Prometaphase Metaphase Anaphase Telophase

Question 26

What happens in prophase?

Answer 26

Chromatin condenses into chromosomes Nucleolus disappears Nuclear membrane disappears Centrioles divide migrate to opposite poles of cell by newly formed spindle fibres

Question 27

What happens in prometaphase?

Answer 27

Spindle fibres attach to centromeres of chromosomes | forming bipolar spindle apparatus

Question 28

What happens in metaphase?

Answer 28

Spindle fibres line up chromosome in the metaphase plate i.e. the middle of the cell

Question 29

What happens in anaphase?

Answer 29

Spindle fibres pull centromeres divide sister chromatids are separated and move to opposite poles of cell

Question 30

What happens in telophase?

Answer 30

Chromosomes decondense into chromatin Nucleolus reappears Nuclear membrane reappears Spindle fibres break down Cleavage furrow forms

Question 31

What happens in cytokinesis?

Answer 31

Cleavage furrow becomes deeper and deeper cytoplasm divides into two forming two cells

Question 32

Where are chromosomes located in interphase?

Answer 32

In the form of chromatin | each homologous pair of chromosomes has its own region in the nucleis where it sits

Question 33

What are homologous chromosomes?

Answer 33

Refer to pairs of chromosomes have the same genes but not necessarily the same alleles

Question 34

How are homologous chromosomes inherited?

Answer 34

One from mother One from father

Question 35

What are the chromatids of homologous chromosomes called? Why?

Answer 35

Non-sister chromatids | because are not identical

Question 36

How many chromosomes are there in a human cell?

Answer 36

46 chromosomes - 23 homologous pairs

Question 37

What is meiosis?

Answer 37

A type of cell division

Question 38

What type of cells does meiosis occur in?

Answer 38

Germ line cells

Question 39

What does meiosis produce?

Answer 39

Four daughter cells are non-identical are haploid

Question 40

What does haploid mean?

Answer 40

Have only one chromosome of each pair | so have half the amount of chromosomes

Question 41

How many rounds of division does meiosis involve?

Answer 41

Two consecutive rounds of division

Question 42

What are the phases of meiosis?

Answer 42

Meiosis 1 - prophase 1 - prometaphase 1 - metaphase 1 - anaphase 1 - telophase 1 same for meiosis 2

Question 43

What extra thing happens in prophase 1?

Answer 43

Homologous chromosomes pair up get crossing over recombination

Question 44

What is crossing over?

Answer 44

Non-sister chromatids in the homologous pair of chromosomes | wrap around each other

Question 45

What is recombination?

Answer 45

Parts of non-sister chromatids break off | swap over and re-attach to chromosome

Question 46

What is the result of crossing over and recombination?

Answer 46

Chromosome is made up of a mixture of maternal and paternal DNA

Question 47

What extra thing happens in metaphase 1?

Answer 47

Random assortment

Question 48

What is random assortment?

Answer 48

Refers to how whether the maternal/paternal chromosome is on the right/left side occurs randomly

Question 49

What is a consequence of random assortment?

Answer 49

Daughter cells recieve mixture of maternal and paternal chromosomes

Question 50

What is the purpose of crossing over, recombination and random assortment?

Answer 50

Increase genetic variation

Question 51

What extra thing happens in anaphase 1?

Answer 51

Homologous chromosomes are separated | move to opposite poles of cell

Question 52

What are the break points of chromosomes in recombination called?

Answer 52

Chiasmata

Question 53

What is the importance of the daughter cells produced by meiosis being haploid?

Answer 53

So that when sperm and egg fuse with each other homologous pairs of chromosomes form and normal number of chromosomes is regained

Question 54

What are alleles?

Answer 54

Different versions of a gene | give different characteristics of that gene

Question 55

What is the pair of homologous chromosomes in meiosis 1 called?

Answer 55

Bivalent/tetrad