lecture 13 - mitosis

Question 1

Where is genetic information in viruses stored?

Answer 1

Acellular RNA

Question 2

Where is genetic information stored in bacteria (prokaryotic cells)?

Answer 2

Circular, single copy, double stranded DNA.

Question 3

How is genetic information stored in eukaryotes?

Answer 3

Histone bound DNA (double helix)

Question 4

How many base pairs fit into a 1µm section?

Answer 4

3000 bp

Question 5

How many genes are in a human DNA strand?

Answer 5

21000 genes

Question 6

What is a karyotype?

Answer 6

An ordered visual representation of the chromosomes in a cell, showing the pairs of homologous chromosomes. In metaphase, each chromosome will be duplicated, so the karyotype will have sister chromatids.

Question 7

What are the two overall phases of the cell cycle in terms of mitosis?

Answer 7

Interphase, mitosis phase (M phase)

Question 8

What are the 3 phases of interphase in the cell cycle?

Answer 8

G1 (gap 1), S (synthesis), G2 (gap 2)

Question 9

What occurs in the G1 phase of the cell cycle?

Answer 9

Organelles, cytoplasmic components and the centrioles replicate inside the cell.

Question 10

What occurs in the S phase of the cell cycle?

Answer 10

DNA is synthesised, replicating the chromosomes to form sister chromatids

Question 11

What occurs in the G2 phase of interphase in the cell cycle?

Answer 11

Enzymes that aid in cell division are produced as the cell prepares for mitosis

Question 12

What kind of cells are centrioles found in?

Answer 12

Animal cells

Question 13

What is a centriole?

Answer 13

A cylindrical organelle made of tubulin that organises spindle fibres during mitosis and meiosis

Question 14

What is a centrosome?

Answer 14

A structure made up of two perpendicular centrioles, which regulates the progression of the cell cycle by organising microtubule arrangement (the spindle)

Question 15

Where are sister chromatids attached?

Answer 15

Centromeres

Question 16

What are the 5 phases of mitosis?

Answer 16

Prophase, Prometaphase, Metaphase, Anaphase, Telophase & cytokinesis.

Question 17

How are chromosomes ordered in the nucleus in G2 of interphase in the cell cycle?

Answer 17

They are disordered

Question 18

What occurs at prophase in mitosis?

Answer 18

Chromosomes become visible, mitosis spindles form at asters and begin to migrate, cytoskeleton disassembles

Question 19

What are asters?

Answer 19

A component in prophase of mitosis. Made up of the centrosome and the microtubules it radiates

Question 20

What occurs at the propmetaphase of mitosis?

Answer 20

Nuclear envelope disintegrates, centromeres of sister chromatids are attached to the poles via mitotic spindles (kinetochore and nonkinetochore microtubules)

Question 21

What are kinetochore microtubules?

Answer 21

A part of the mitotic spindle that attach the kinetochore of sister chromatids to the centrosomes

Question 22

What are nonkinetochore microtubules?

Answer 22

A component of the mitotic spindle that connect the centrosomes at opposite poles of the cell, but do not interact with the sister chromatids

Question 23

What occurs in the metaphase of mitosis?

Answer 23

Sister chromatids are lined up long ways in the centre of the cell along the metaphase plate, due to equal and opposite forces applied by the kinetochore microtubules.

Question 24

What is the ‘equator’ of a cell in metaphase called?

Answer 24

The metaphase plate

Question 25

What occurs during Anaphase of mitosis?

Answer 25

Sister chromatids are pulled apart as the kinetochore microtubules shorten and the nonkinetochore microtubules lengthen. Each pair of sister chromatids splits into two daughter chromosomes.

Question 26

What occurs in the telophase and cytokinesis phases of mitosis?

Answer 26

Spindle apparatus disassembled and microtubules broken down in tubulin for forming new cytoskeleton in daughter cells. chromosomes cluster at poles and nuclear envelope forms around them. Cleavage furrow forms, key organelles reappear in each cell.

Question 27

How does the cleavage furrow split the parent cell in cytokinesis of mitosis/meiosis?

Answer 27

A constricting belt of actin filaments forms around the equator of the cell and tightens to split the cell.

Question 28

What are the the cell cycle checkpoints? (3)

Answer 28

G1/S, G2/M, spindle checkpoint

Question 29

What is the primary checkpoint in the cell cycle?

Answer 29

G1/S checkpoint

Question 30

What is the function of the G2/M cell cycle checkpoint?

Answer 30

Allows cells that have successfully completed the phases of interphase to begin mitosis

Question 31

What occurs at the spindle checkpoint in the cell cycle?

Answer 31

Checkpoint ensures all chromosomes have attached to spindles for anaphase to proceed.

Question 32

What is the gene copy number?

Answer 32

The number of copies of a particular gene in the genotype of an individual. (AKA copy number variation - CNVs)

Question 33

What is the chromatid number?

Answer 33

The number of chromatids in a cell, with two for every duplicated chromosome.

Question 34

What is the diploid chromosome number?

Answer 34

The number of chromosomes in a cell, with two for every homologous pair. There are 46 chromosomes in a normal cell.

Question 35

What is the haploid number?

Answer 35

Symbol is n. The number of chromosomes in a haploid cell or gamete, which is equal to the number of homologous pairs in a diploid cell.