5. Mitotic Cell Cycle

Question 1

How many chromosomes in human cells?

Answer 1

46

Question 2

2 identical chromatids of a chromosome?

Answer 2

sister chromatid

Question 3

Centre of a chromosome?

Answer 3

centromere

Question 4

What is mitosis?

Answer 4

the division of a nucleus into 2 identical daughter cells

Question 5

Describe the mitotic cell cycle

Answer 5

interphase: G1, S, G2
mitosis/nuclear division
cytokinesis

Question 6

What is G1?

Answer 6

gap 1, where the cell grows

Question 7

What is S?

Answer 7

DNA synthesis, centrosome replicates

Question 8

What is G2?

Answer 8

gap 2, the cell continues to grow and new DNA made during S phase is checked

Question 9

What are the stages of mitosis?

Answer 9

prophase
metaphase
anaphase
telophase

Question 10

Describe prophase

Answer 10

1) nucleolus disappears, nuclear envelope breaks down

2) centrosomes move to opposite poles

3) visible chromosomes as the chromatin coils up, chromosomes seen to have 2 identical chromatids

Question 11

Describe metaphase

Answer 11

metaphase: middle

1) chromosomes line up in the middle

2) spindle fibres start to form from the centrosomes at opposite poles

Question 12

Describe anaphase

Answer 12

anaphase: apart

1) spindle fibres attach to the centromeres

2) sister chromatids are pulled apart, forming V shapes

3) centromere split in half

Question 13

Describe telophase

Answer 13

1) nuclear envelope reforms, nucleolus reappears

2) chromatin uncoils

Question 14

What is cytokinesis?

Answer 14

the division of the cytoplasm and cell into 2 when the cell membrane constricts

Question 15

Where in the centromere do spindle fibres attach?

Answer 15

kinetochore

Question 16

What do microtubules do to pull the sister chromatids apart?

Answer 16

shorten

Question 17

What is mitosis for? (3)

Answer 17

1) growth of multicellular organisms from unicellular zygote (gamete + gamete)

2) repair of tissues by replacement of dead/damaged cells

3) asexual reproduction

Question 18

What are telomeres?

Answer 18

repetitive sequence of DNA found at the ends of chromosomes, protects genes from chromosome shortening that results from each cell division

Question 19

What enzyme adds bases to the telomeres?

Answer 19

telomerase

Question 20

What happens when telomeres run out?

Answer 20

When the vital DNA is no longer protected, the cell dies.

Question 21

What is a stem cell?

Answer 21

a cell that can divide an unlimited number of times by mitosis.

each new cell it produces can either remain a stem cell or differentiate into a specialised cell

Question 22

What is potency?

Answer 22

the power of a stem cell to produce different types of cell

Question 23

What are totipotent cells?

Answer 23

cells that can produce any type of cell

Question 24

The more specialised a cell is…

Answer 24

…the more they lose their ability to divide by mitosis

Question 25

Define mutation

Answer 25

a change in any gene

Question 26

What is a mutated gene that causes cancer called?

Answer 26

oncogene

Question 27

What are the 2 types of tumours?

Answer 27

benign and malignant

Question 28

What is it called when secondary tumours form by spreading through the blood and lymphatic system?

Answer 28

metastasis