Mitosis - Cell Division

Question 1

what is a karyotype

Answer 1

an ordered, visual representation of the chromosomes in a cell

Question 2

what is a homologous chromosome

Answer 2

a pair of chromosomes with the same genes, one inherited by the father and one from the mother

Question 3

what is the locus

Answer 3

location of the gene

Question 4

what is a gene

Answer 4

a defined region (sequence) of DNA that produces a type of RNA molecule that has some function
it is a unit of hereditary information

Question 5

what is an allele

Answer 5

an alternate version of a gene

Question 6

what phases are included in the interphase

Answer 6

1. G1 phase
2. S phase
3. G2 phase

Question 7

what occurs during the G1 phase

Answer 7

metabolic activity and growth

Question 8

what occurs during the S phase

Answer 8

metabolic activity, growth and DNA synthesis (DNA replication)

Question 9

what occurs during the G2 phase

Answer 9

metabolic activity, growth and preparation for cell division
- the nuclear envelope is still intact
- nucleolus is visible
- 2 centromeres form
- duplicated chromosomes are not yet condensed/visible

Question 10

what processes are included in the mitotic phase

Answer 10

• mitosis
• cytokinesis

Question 11

what is a duplicated chromosome

Answer 11

consists of 2 sister chromatids, which are genetically identical

Question 12

what are centromeres

Answer 12

constricted regions on chromosomes where sister chromatids are joined

Question 13

what are centrosomes

Answer 13

organelle in the cell that produces spindle fibres

Question 14

what are the 5 phases of mitosis

Answer 14

1. prophase
2. prometaphase
3. metaphase
4. anaphase
5. telophase and cytokinesis

Question 15

explain the first phase of mitosis

Answer 15

Prophase
- nucleoli disappears
- duplicated chromosomes condense and appear as 2 identical sister chromatids joined together at centromeres
- mitotic spindle begins to form; microtubules lengthen and the centromeres move to opposite poles

Question 16

explain the second phase of mitosis

Answer 16

Prometaphase
- nuclear envelope breaks down and chromosomes fully condense
- a kinetochore forms at the centromere of each chromatid
- kinetochore microtubules attaches to kinetochores
- non kinetochore microtubules lengthen the cell by interacting with those from the opposite pole of the spindle

Question 17

explain the third phase of mitosis

Answer 17

Metaphase
- centromeres are now at opposite poles of the cell
- kinetochore microtubules are attached to the kinetochore of all sister chromatids
- duplicated chromosomes align at the metaphase plate (cell equator)
- homologous pairs do not interact
- centromeres lie on the metaphase plate, an equal distance between the spindles of 2 poles

Question 18

explain the fourth phase of mitosis

Answer 18

Anaphase
- sister chromatids disjoins at the centromeres and each chromatid becomes an independent daughter chromosomes
- daughter chromosomes moves towards opposite poles as their kinetochore microtubules shorten
- non kinetochore microtubules lengthen and cell elongates
- anaphase ends when the 2 poles of the cell contain identical and complete collections of chromosomes

Question 19

explain the last phase of mitosis

Answer 19

Telophase
- chromosomes become less condense
- spindle microtubules breakdown
2 daughter nuclei (w nuclear envelope) form in the cell - Nucleoli reappear
- Mitosis is complete
Cytokinesis
- the cytoplasm divides, resulting in 2 daughter cells
in animal cells: the formation of a cleavage furrow which pinches the cell into 2
in plant cells: the formation of a cell plate between the daughter cells

Question 20

what is the end product of mitosis

Answer 20

two identical daughter cells that each have one copy of each duplicated chromosome