Cell Cycle

Question 1

What shape do chromosomes have?

Answer 1

X-shaped

Question 2

What is the short arm of the chromosome called?

Answer 2

p-arm

Question 3

What is the long arm of the chromosome called?

Answer 3

q-arm

Question 4

What is karyoptype?

Answer 4

A picture of a person’s chromosomes

Question 5

What are chromatids?

Answer 5

2 chromatids are joined to form a chromosome and 1 chromatid will go to each daughter cell

Question 6

In what kind of cells is there 1 chromosome from each parent?

Answer 6

Somatic cells

Question 7

What are the 46 chromosomes comprised of?

Answer 7

22 homologous pairs and 2 sex chromosomes

Question 8

What differs in the chromosomes of males and females?

Answer 8

Females have 2 homologous X chromosomes and males have 1 X and 1Y chromosome

Question 9

What stage comes before cell division?

Answer 9

Interphase

Question 10

What is the restriction point?

Answer 10

Decides if cell will continue to S phase or will enter G0

Question 11

What is G1?

Answer 11

The first of 2 gap stages in which all cell content except genetic material is duplicated

Question 12

What is G0?

Answer 12

G0 is cell cycle arrest and can be reversible (quiescence) or irreversible (senescence)

Question 13

Why is senescence triggered?

Answer 13

In ageing and damaged cells to safeguard against cancer

Question 14

How can arrested cells be lost?

Answer 14

Through apoptosis (programmed death)

Question 15

How is apoptosis carried out?

Answer 15

Controlled by P53 protein

Question 16

What can prevent apoptosis?

Answer 16

Mutations in P53 protein

Question 17

What happens in S phase?

Answer 17

Chromosomes are duplicated to form sister chromatids

Question 18

Why is S phase short?

Answer 18

To prevent interference with DNA replication

Question 19

What phase follows S phase?

Answer 19

G2

Question 20

What happens in G2 phase?

Answer 20

DNA replication is accuracy checked and centrioles are duplicated as they act as seed points for the formation of spindle

Question 21

How is G2 regulated?

Answer 21

P53 protein

Question 22

What phase follows G2?

Answer 22

M Phase

Question 23

How many stages are in M phase?

Answer 23

5

Question 24

What is the first stage of M phase?

Answer 24

Prophase

Question 25

What happens during prophase?

Answer 25

Chromosomes condense and spindles begin to form. These spindles consist of an array of microtubules which grow from centrioles at either end of the cell

Question 26

What stage is after Prophase?

Answer 26

Prometaphase

Question 27

What happens in prometaphase?

Answer 27

The nuclear envelope breaks down and releases chromosomes. Chromosomes are organised by attaching to microtubules.

Question 28

What happens after the chromosomes attach to microtubules in prometaphase?

Answer 28

The microtubules bind to kinetochores which are proteins on the centromere of the chromosome

Question 29

What stage is after prometaphase?

Answer 29

Metaphase

Question 30

What happens in metaphase?

Answer 30

Chromosomes align along the spindle equator and the kinetochores and microtubules are responsible for this alignment

Question 31

What 2 stages happen after metaphase?

Answer 31

Anaphase and Telophase

Question 32

What happens in anaphase?

Answer 32

The sister chromatids separate and 2 identical sets of chromosomes move to each end of the cell

Question 33

What happens in telophase?

Answer 33

Spindle disappears and chromosomes decondense. New nuclear membranes are then formed

Question 34

What happens in cytokinesis?

Answer 34

The cytoplasm divides and yields 2 identical daughter cells

Question 35

Why does BRCA1 mutations predispose for cancer?

Answer 35

BRCA1 codes for correcting in errors in DNA and is a tumour suppressant. DNA can't be checked for errors if this gene is mutated so a more erroneous method is used.

Question 36

What is meiosis?

Answer 36

Meiosis is the formation of gametes

Question 37

How many cells are produced in meiosis?

Answer 37

4 very different haploid cells

Question 38

What is the stage before Meiosis I called?

Answer 38

Gametogonium

Question 39

What happens in Meiosis I?

Answer 39

DNA is replicated and 2 sister chromatids are generated

Question 40

What happens during prophase in Meiosis I?

Answer 40

Chromosomes cross over and swap DNA to ensures that we do not receive a complete set of chromosomes from 1 parent

Question 41

What happens during metaphase in Meiosis I?

Answer 41

The crossed over chromosomes move to the equator of the cell

Question 42

How many chromosomes do daughter cells have after Meiosis I?

Answer 42

23

Question 43

What is non-disjunction?

Answer 43

When the DNA is not divided equally amongst the cells

Question 44

What can dis-junction cause?

Answer 44

Gametes with 1 too many or 1 too little chromosomes

Question 45

What is a trisomy?

Answer 45

When an embryo has 3 of 1 chromosome. Most are fatal but DS is Trisomy 21 and not fatal

Question 46

What happens in Meiosis 2?

Answer 46

Meiosis 2 is a replica of Meiosis 1 so that 4 gametes are produced