Cell Division and Cellular Organisation

Question 1

what happens during prophase [5]

Answer 1

• chromosomes become visible as DNA coils condense
• Nucleolus denuclearises appears
• centrioles move apart to opposit poles of the cell
• spindle fibres form from microtubules
• nuclear membrane breaks down

Question 2

what happens during metaphase [3]

Answer 2

• centrioles reach poles and spindle is complete
• chromosomes moved by spindle fibres to line up along the equator/metaphase plate of the cells w/ chromatids facing opposite poles
• mitotic spindle created

Question 3

what happens during anaphase [3]

Answer 3

• centromeres holding chromatids divide
• microtubules from the spindle pull the chromatids apart
• they move to opposite poles

Question 4

what happens during telophase [4]

Answer 4

• chromatids reach each pole & become the new chromosomes of the daughter cells
• microtubules making up the spindle break down
• nuclear envelope reforms
• chromosomes uncoil and become long and thin again

Question 5

what is cytokenisis

Answer 5

• division of the cytoplasm
• a cell division stage in the mitotic phase of the cell cycle that results in the production of 2 identical daughter cells

Question 6

what is the centromere

Answer 6

• region at which 2 chromatids are held together

Question 7

what is are chromatids

Answer 7

• 2 identical copies of DNA held together at a centromere

Question 8

what is chromatin

Answer 8

uncondensed and coiled DNA in a complex with histones

Question 9

what is a cleavage furrow

Answer 9

• formed in around the middle of animal cells when the cell surface membrane is pulled inwards by the cytoskeleton until it is close enough to fuse around the middle and form 2 cells

Question 10

what is the cell plate and how is it formed

Answer 10

• vesicles form the golgi apparatus begin to assemble in the same place where the metaphase plate was formed
• vesicles fuse with each other and the cell surface membrane, dividing the cell into 2

Question 11

what is mitosis

Answer 11

cell division which forms 2 genetically identical daughter cells

Question 12

what is mitosis used for

Answer 12

• growth and tissue repair

- asexual reproduction

Question 13

name (in order starting after a division) the stages of the cell cycle

Answer 13

• Gap phase 1 (G1)
• Synthesis (S-Phase)
• Gap phase 2 (G2)
• Mitosis & cytokenisis

Question 14

which phases occur during interphase

Answer 14

• G1
• S-phase
• G2

Question 15

what are the three checkpoints

Answer 15

• G1 checkpoint
• G2 checkpoint
• Metaphase checkpoint

Question 16

what happens in G1 checkpoint

Answer 16

the cell is checkedcto see that it divided correctly

Question 17

what happens to a cell in G1 checkpoint if it is not okay

Answer 17

• the cell cycle stops and the cell goes through apoptosis

Question 18

what happens in G2 checkpoint

- what happens if the DNA has mutations or is damaged

Answer 18

• cell checks if the DNA has been replicated properly

- cell cycle is stopped/DNA is repaired

Question 19

what is checked in the metaphase checkpoint

Answer 19

• cell checks that chromosomes have attached to the spindle