cell cycle

Question 1

what is cell prefiguration

Answer 1

a cell making new cells

Question 2

which cell is the most specialised cell in the human body

Answer 2

nerve cell

Question 3

why does cell death have to occur

Answer 3

in order for cells to maintain their functionality

Question 4

why do we study the cell cycle

Answer 4

for drug development

Question 5

why do cells need to replicate

Answer 5

in our everyday life we come into contact with things that can cause damage to cells or even cell death

Question 6

give examples of things in everyday life that can cause cell damage or cell death

Answer 6

UV
chemical damage
thermal damage
mutation
premature ageing

Question 7

is unicellular replication faster than multicellular

Answer 7

yes

Question 8

where are most of the cells in the cell cycle and what are they doing

Answer 8

in the resting phase G0 where they are incredibly active in function and responses, but are not going through the cell cycle

Question 9

what do all cells require to move into G1

Answer 9

a chemical trigger

Question 10

what is G1 phase

Answer 10

gap/growth phase 1 - where the cell grows

Question 11

what is towards the end of G1 and what do all cells require to get past it?

Answer 11

a restriction point and they require another chemical trigger

Question 12

what phase comes after G1

Answer 12

the S phase

Question 13

what happens in the S phase of the cell cycle

Answer 13

DNA replication

Question 14

what phase comes after the S phase

Answer 14

G2

Question 15

what happens in gap phase 2

Answer 15

the cell prepares to divide

Question 16

what phase is after the G2 phase

Answer 16

the M phase

Question 17

what happens in the M phase

Answer 17

where the cell undergoes mitosis

Question 18

how long does the cell cycle take in human cell

Answer 18

24 hours

Question 19

what parts of the cell cycle are interphase

Answer 19

G0, G1, S, G2

Question 20

what do the checkpoints in the cell cycle do?

Answer 20

monitor the status of the cell; cell size, adequate supply of nutrients, DNA quality and quantity, favourable environment

Question 21

what regulates the checkpoints

Answer 21

signals from:
other cells
growth factors
other extracellular signal molecules

Question 22

where do stops occur in the cell cycle and why

Answer 22

• in the G1 phase if the DNA is damaged
• in the S phase if not all DNA is replicated
• in the G2 phase if DNA is damaged
• in the M phase if chromosomes are misaligned

Question 23

what are the two types of cell division

Answer 23

mitosis and meiosis

Question 24

which cells does mitosis occur in and what type of reproduction is it

Answer 24

somatic cells - asexual reproduction

Question 25

which cells does meiosis occur in and what type of reproduction is it

Answer 25

specific reproductive cells - sexual reproduction

Question 26

what are the 5 phases of mitosis

Answer 26

prophase prometaphase metaphase anaphase telophase

Question 27

what does mitosis produce

Answer 27

two genetically identical daughter cells that are identical to the parent cell

Question 28

what happens during prophase in mitosis

Answer 28

- Genetic material condenses to prevent chromosomes tangling i.e. easier to separate ○ Chromosomes become visible - Centrioles are two poles at opposite sides of the cell - Active DNA needs to be unbound - Mitotic spindle assembles between the two centrosomes - Nucleolus disappears

Question 29

what happens during prometaphase in mitosis

Answer 29

- The nuclear membrane breaks down, releasing the centrosomes ○ Allows centrosomes to interact with chromosomes to build the mitotic spindle - Chromosomes further condense - A kinetochore (point where the sister chromatids are attached) forms at the centromere - The chromosomes attach to the mitotic spindle

Question 30

what happens during metaphase in mitosis

Answer 30

- Chromosomes align on an axis (the metaphase plate) - The spindle consists of microtubules, one attached to each chromosome - Chromosomes act independently and align randomly

Question 31

what happens during anaphase in mitosis

Answer 31

- Each centromere splits ○ Results in two free chromatids (called sister chromatids) - Each chromatid moves towards a pole - Cell changes shape becoming elongated due to microtubules not associated with the kinetochore

Question 32

what happens during telophase in mitosis

Answer 32

- Formation of nucleolus and nuclear membrane - Short and thick chromosomes begin to elongate to form long and thin chromatin - Formation of the cleavage furrow (a shallow groove in the cell near the old metaphase plate) ○ Position is determined by the spindle

Question 33

what is cytokinesis

Answer 33

Pinching of cytoplasm due to contraction of ring of actin and myosin 2 filaments

Question 34

what happens during meiosis

Answer 34

Diploid germ cells (2N) undergo DNA replication followed by two rounds of division (meiosis 1 and meiosis 2)

Question 35

what type of cells does meiosis produce

Answer 35

haploid cells called gametes

Question 36

why is genetic diversity important

Answer 36

○ Facilitates evolution ○ Lack of diversity promotes genetic disease ○ A healthy population had a large gene pool

Question 37

name two ways genetic diversity occurs during meiosis

Answer 37

○ Independent assortment of chromosomes ○ Crossing over (genetic exchange)

Question 38

what is the difference in metaphase between meiosis and mitosis

Answer 38

in meiosis the orientation is random and crossing over can also occur

Question 39

what difference occurs during telophase 1 in meiosis when compared to mitosis

Answer 39

in meiosis the nuclear envelope usually does not reform as the chromosomes will undergo mitosis again

Question 40

what does each primary spermatocyte produce

Answer 40

2 secondary spermatocytes

Question 41

what does each secondary spermatocyte produce

Answer 41

2 spermatozoa

Question 42

what happens when spermatids mature

Answer 42

cytoplasm is lost, nucleus condenses and acrosome forms