Lecture 1+2: Mitosis and the Cell Cycle

Question 1

What are the 4 main stages of the cell cycle?

Answer 1

G1, S, G2. M.

Question 2

What happens in the first stage of the interphase?

Answer 2

G1: The cell does normal cellular functions, grows in size (particularly in newly divided daughter cells that are half the size of the mother cell).

Question 3

What happens in the second stage of interphase?

Answer 3

S: DNA is replicated via synthesis. Each chromosome is replicated (2 sister chromatids attached at the centromere)
Chromosomes are not condensed yet.

Question 4

What happens in the third stage of interphase?

Answer 4

G2: the cell continues to grow and acquires proteins for cell division. There is a checkpoint stage in which proteins flag any mistakes in the cell and arrest the cell until the problem is fixed or instructs the cell to self-destruct.

Question 5

What are the 5 stages of mitosis?

Answer 5

PMATC: Prophase, Metaphase, Anaphase, Telophase, Cytokinesis.

Question 6

What happens in Prophase?

Answer 6

The nucleus dissolves and newly replicated chromosomes begin to condense.

Question 7

What happens in metaphase?

Answer 7

The nucleus is fully dissolved and condensed chromosomes are pulled by microtubules that have attached to the kinetochore; these microtubules align chromosomes along the metaphase plate

Question 8

What is a kinetochore?

Answer 8

A part of a chromosome that contains the centromere and other binding proteins.

Question 9

What happens in Anaphase?

Answer 9

Each sister chromatid is pulled by microtubules to each pole of the dividing cell.

Question 10

What happens in telophase?

Answer 10

Identical sets of chromosomes are separated. The nucleus begins to reform around the decondensing chromosomes.

Question 11

What happens in Cytokinesis?

Answer 11

Microtubules constrict the metaphase plate and cause a cleavage, this is eventually partitioned and two daughter cells are created.

Question 12

What stage of interphase to cells undergoing Meiosis not have?

Answer 12

G2

Question 13

What is unique about the neural cell cycle?

Answer 13

Neuron cells do not replicate, they stay in a G0 phase.

Question 14

Describe changes in the chromosome amount (n) throughout mitosis.

Answer 14

2n throughout

Question 15

Describe how the number of sister chromatids change throughout the cell cycle

Answer 15

1 chromatid per chromosome in G1, 2 in G2, 2 in Prophase, 1 after Mitosis.

Question 16

How does the DNA number (c) change throughout the cell cycle?

Answer 16

G1: 2c G2: 4c End of Mitosis: 2c

Question 17

If species A has 2n=4 chromosomes and B has 2n=12 chromosomes, which species has more DNA?

Answer 17

Chromosomes differ in size and structure therefore its impossible to tell

Question 18

What parts of the chromosome contain the least genetically important information?

Answer 18

Centromeres, telomeres.

Question 19

What would happen if a chromosome had two centromeres?

Answer 19

The chromosome would be torn apart during division by microtubules.

Question 20

What is the relationship between genomes and genes?

Answer 20

larger genomes tend to have more genes and tend to be more complex.

Question 21

What is cohesin?

Answer 21

heterotrimer rings that bind to one chromosome and are broken during anaphase to separate sister chromatids.

Question 22

Cells that are 2n are called

Answer 22

diploid

Question 23

cells that are n are called

Answer 23

haploid

Question 24

All the genes in a haploid are called

Answer 24

a genome

Question 25

Protected cohesin

Answer 25

Hold sister chromatids together

Question 26

Unprotected choesins

Answer 26

Hold homologous pairs together

Question 27

What is the function of meiosis?

Answer 27

To produce gamete cells from diploid cells

Question 28

What are the stages of meiosis?

Answer 28

Prophase 1, Metaphase 1, Anaphase 1, Telophase 1. All in 2.

Question 29

What is the major event in meiosis 1?

Answer 29

Homologous pairs are separated into separate cells (2n to n)

Question 30

What is the major event in meiosis 2?

Answer 30

Sister chromatids are separated into cells (2c to c)

Question 31

When does crossing over happen?

Answer 31

Metaphase 1

Question 32

When do diploid cells become haploid cells during Meiosis?

Answer 32

After metaphase 1

Question 33

What is it called when homologous pairs align along the metaphase plate during meiosis 1.

Answer 33

They create a tetract.

Question 34

When does protected cohesin break?

Answer 34

during anaphase 1

Question 35

when does unprotected cohesin break?

Answer 35

during anaphase 2

Question 36

Describe how n changes during meiosis

Answer 36

G2: 2N Meiosis 1: 2n to n, Meiosis 2: n

Question 37

Describe how c changes during meiosis

Answer 37

G1: 2c G2: 4c Meiosis 1: 4c to 2c Meiosis 2c to c

Question 38

What is gametogenesis?

Answer 38

meiosis when the products are gametes

Question 39

What is meiosis in males?

Answer 39

spermatogenesis

Question 40

What is meiosis in females?

Answer 40

oogenesis

Question 41

What occurs to haploid cells after spermatogenesis?

Answer 41

The cells grow flagella to become motile (sign of mature sperm)

Question 42

What is unique about the product of oogenesis?

Answer 42

Makes a single gamete rather than 4.

Question 43

What are discarded cells in oogenesis called?

Answer 43

polar bodies

Question 44

How many chromosomes are in the adult human?

Answer 44

2n=46, 2 pairs of 23 (maternal + paternal)

Question 45

When is the zygotic genome activation?

Answer 45

Genes turn on at the 4 cell stage

Question 46

What is the probability of having a single child?

Answer 46

97%

Question 47

What is a dizygotic twin?

Answer 47

non-identical twins produced from two separately fertilized eggs (have their own separate placentas and containers.

Question 48

What is the probability of having a dizygotic twin?

Answer 48

3%

Question 49

What is a monozygotic twin?

Answer 49

genetically identical twins that come from one zygote that either splits at the two-cell stage (one container) or after the two-cell stage (separate containers).

Question 50

What to fertility drugs increase the rate of?

Answer 50

increase rate that eggs are released therefore increases the probability of dizygotic twins.

Question 51

What kind of cells does amniotic fluid contain?

Answer 51

embryonic cells

Question 52

Why does oogenesis pause in prophase 1?

Answer 52

maternal age effects