Cell cycle

Question 1

What is the longest phase of the cell cycle?

Answer 1

Interphase

Question 2

What parts is interphase divided into?

Answer 2

G1 (cell contents replicated. Increase in size.)
S- (DNA REPLICATION)
G2 - (more cell growth)

Question 3

What is the G0 stage?

Answer 3

A period where the cell stops replicating as there are no signals sent for division. This can be temporary or permanent and usually occurs during G1.

Question 4

How many checkpoint are there during interphase?

Answer 4

3

Question 5

What occurs at the checkpoint to allow the cycle to continue?

Answer 5

The proteins controlling the checkpoints are phosphorylated

Question 6

What occurs if checkpoint proteins are not phosphorylated?

Answer 6

The cell either repairs the damage or undergoes apoptosis

Question 7

When does the 4th checkpoint occur?

Answer 7

Before the chromosome spilt (during metaphase) to ensure the chromosomes are correctly aligned

Question 8

What are the 5 stages of Mitosis?

Answer 8

Prophase, metaphase, anaphase, telophase and cytokinesis

Question 9

What is the structure of a chromosome??

Answer 9

They consist of a short (p) arm and a long (q) arm and are held together by a centromere

Question 10

What are the 4 chromosome structures due to centromere placement?

Answer 10

Metacentric, submetacentric, Acrocentric and telocentric

Question 11

What occurs in prophase?

Answer 11

Nuclear Membrane disappears, chromosomes form

Question 12

What happens in prometaphase?

Answer 12

Spindle fibres bind to centromeres, nuclear Membrane has completely disappeared

Question 13

What happens in metaphase?

Answer 13

Replicated chromosomes align at the metaphase plate

Question 14

What happens in anaphase?

Answer 14

Microtubules spindle pulls chromosomes apart to opposite poles

Question 15

What happened in telophase?

Answer 15

Spindle disappeared, nuclear envelope reforms and a cleavage furrow forms as the cells start to be cleaved

Question 16

What are homologous chromosome?

Answer 16

Chromosomes that have the same genes in the same loci, but different forms of the genes (alleles)

Question 17

What does meiosis results in?

Answer 17

4 non-identical haploid cells

Question 18

What stage is present in mitosis but not meiosis?

Answer 18

Prometaphase

Question 19

What occurs in Prophase 1 of meiosis?

Answer 19

Synopsis occurs where the homologous chromosome pair up and crossing over occurs between non sister chromatids to form recombinant DNA

Question 20

What is the importance of crossing over?

Answer 20

It gives genetic variation

Question 21

What are the points at which crossing over occurs called?

Answer 21

Chiasmata

Question 22

How is metaphase 1 in meiosis different?

Answer 22

The homologous pairs (bivalents) line up on the metaphase plate and there is independent assortment of bivalents

Question 23

How is metaphase II different from metaphase I?

Answer 23

There is independent assortment of CHROMATIDS instead of BIVALENTS

Question 24

What is the consequence of meiosis?

Answer 24

It allows the chromosome number to remain constant from generation to generation

Question 25

What is spermatogenesis?

Answer 25

Cell division(meiosis) to make male gametes

Question 26

What is the time length of spermatogenesis?

Answer 26

60 days

Question 27

Outline spermatogenesis

Answer 27

The spermatogonium (diploid) divides by mitosis to make primary spermatocytes (diploid). These then undergo meiosis I to produce 2 secondary spermatocyte each which then undergoes meiosis II so that 4 spermatids are produced that develop into sperm cells

Question 28

What is oogenesis?

Answer 28

Cell division by meiosis to produce female gametes

Question 29

Outline oogenesis

Answer 29

The Oogonium divides by mitosis to produce primary oocytes. The primary oocytes undergo meiosis to produce 1 mature ovum and 3 polar bodies.

Question 30

How long does oogensis take?

Answer 30

12-50 years

Question 31

When are primary oocytes produced?

Answer 31

In the foetus and then the final stage of meiosis occurs after fertilisation

Question 32

What is nondisjunction?

Answer 32

Failure to separate chromosomes properly during meiosis

Question 33

What is aneuploidy?

Answer 33

Having not normal amounts of chromosomes

Question 34

Is nondisjunction occurs in meiosis I how many of the daughter cells are affected?

Answer 34

All 4

Question 35

If nondisjunction occurs in meiosis II how many daughter cells are affected?

Answer 35

Only 2

Question 36

What is karyotyping?

Answer 36

A type of chromosome analysis

Question 37

What is trisomy?

Answer 37

A cell which contains 3 of the same chromosomes instead of 2

Question 38

What is monosomy?

Answer 38

When a cell contains only 1 chromosome of a pair

Question 39

What is non-mosaic karyotype?

Answer 39

When a nondisjunction occurs in the first post-zygotes division and so all cells in the body are affected

Question 40

What is mosaic karyotype?

Answer 40

When non-disjunction occurs in later divisions and so not all cells are affected.

Question 41

What are centrosomes?

Answer 41

Organelles that organise microtubules in the cell cycle. There are 2 in a cell

Question 42

What happens when you have more than 2 centrosomes?

Answer 42

There are multipolar spindles (chromosomes are pulled apart in multiple directions)