mitosis

Question 1

why is cellular division important

Answer 1

• growth by increasing cell number
• replacing cells/repair of tissue
• asexual reproduction/cloning

Question 2

3 cell cycles

Answer 2

interphase - chromosomes not visible, nucleus intact, proteins being synthesised, DNA replication occurs

mitosis - cells divide into 2 daughter cells with identical DNA (from earlier replication)

cytokinesis - division of the cell membrane and cytoplasm to form 2 separate cells

Question 3

4 mitosis phases

Answer 3

PMAT

prophase, metaphase, anaphase, telophase

Question 4

prophase

Answer 4

chromosomes become visible

centrosomes move to opposite poles of the cell and form spindle fibres

nuclear membrane breaks down

nucleolus dissolves

Question 5

metaphase

Answer 5

chromosomes (each consisting of two chromatids) become attached to the spindle fibres by their centrosomes

align at the centre of the cell

Question 6

anaphase

Answer 6

centromeres divide, separating each pair of sister chromatids

the spindle fibres contract, pulling the chromatids to opposite poles of the cell by their centromeres

Question 7

telophase

Answer 7

once the chromosome sets are at the poles, the spindle fibres dissolve

chromosomes dencondese

nuclear membranes reform around each chromosome set

cytokinesis occurs, splitting the cell into 2

Question 8

what is cancer

Answer 8

the result of damage to mitosis regulating genes which leads to uncontrolled cell division

if cells within the faulty region don’t die, they divide and pass on the mutation to daughter cells which all divide uncontrollably, forming tumours

Question 9

how do cancer drugs work

Answer 9

eg chemotherapy

disrupt cell cycle by stopping DNA replication/spindle formation

chemo drugs have the greatest impact on cells that rapidly divide - eg cancer cells/ hair follicle cells

Question 10

division in prokaryotic cells

Answer 10

binary fission - viruses cannot do this alone, they use living hosts

Question 11

binary fission

Answer 11

1 circular DNA replicates
2 plasmids replicate
3 cell membrane grows between cells and pinches
4 new cell wall forms between cells, dividing cell in two

Question 12

viral replication steps

Answer 12

attachment
entry
replication/transcription/translation
assembly
release

Question 13

why is DNA replication needed before cell division

Answer 13

so cells can have identical DNA

so cells can have enough DNA

Question 14

in which phase do sister chromatids get separated

Answer 14

anaphase

Question 15

why are the two cells at the end of mitosis identical

Answer 15

both cells received an identical sister chromatid

Question 16

why is prokaryotic cell division generally much quicker than eukaryotic cell division

Answer 16

simpler, less structures, less DNA

Question 17

name two processes that occur during interphase

Answer 17

protein synthesis, DNA replication

Question 18

mitosis

Answer 18

a part of the cell cycle in eukaryotic cells in which a parent cell divides to produce two genetically identical daughter cells

Question 19

dot in diagram

Answer 19

centriole,

the function is to move to the opposite ends of the cell and create the spindle (a network of protein fibres that move the chromosomes and pull them apart)