2.1.6 Cell division, cell diversity and cellular organisation

Question 1

Cell cycle

Answer 1

highly ordered and carefully controlled sequence of events that prepare a cell for division and check the cell has divided properly before the next division

Question 2

3 main stages of cell cycle

Answer 2

interphase
mitosis
cytokenesis

Question 3

What are the different stages of interphase in the cell cycle

Answer 3

G1
S
G2

Question 4

what is G1

Answer 4

proteins are produced and organelles and replicated
increase in cell size

Question 5

What is S

Answer 5

synthesis phase
DNA is replicated in the nucleus

Question 6

What is G2

Answer 6

2nd growth stage
cell continues to increase in size
energy stores increase duplicated Dna is checked for errors

Question 7

why does S occur between G1 and G2

Answer 7

Dna needs to be in nucleus and checked after

Question 8

whuch organelle self replicates in G1

Answer 8

mitchondria and chloroplast as they have there own DNA to replicate

Question 9

Stage 2 of cell cycle

Answer 9

Mitosis
division of nucleus only

Question 10

Stage 3 of cell cycle

Answer 10

cytokenesis
cytoplasm divides to form 2 seperate cells

Question 11

cytokenesis in animal cells

Answer 11

cleavage furrow forms in middle of cell
plasma membrane is pulled in by cytoskeleton
when close enough to fuse in middle 2 new cells form

Question 12

cytokenesis in plant cell

Answer 12

vesicles from golgi assemble where metaphase plate forms
vesicle fuse with plasma membrane and eachother and cell divide into 2

Question 14

name of pphase leaving the cell cyle

Answer 14

G0

Question 15

G0

Answer 15

phase cell enters when leaves cycle
temporary or permanent
when in G0 cell can’t divide

Question 16

reasons why cell enters G0

Answer 16

differentiation
Dna damage

Question 17

G1 checkpoint

Answer 17

end of G1 before S

Question 18

G2 checkpoint

Answer 18

checks Dna is replicated without error

Question 19

spindle assembly checkpoint

Answer 19

point in mitosis where all chromosomes should be attached to spindle fibres and alligned

Question 20

uses of mitosis

Answer 20

growth- make more cells
tissue repair- damaged or worn tissue is replaced
asexual reproduction- produce genetically identical offspring

Question 21

centriole

Answer 21

cyclindrical prganelle composed of microtubules which produce spindle fibres

Question 22

centrosome

Answer 22

2 centrioles at right angles to eachother

Question 23

chromatid

Answer 23

one strand of replicated chromosome

Question 24

chromosome

Answer 24

long strand of Dna composed of many genes

Question 25

centromere

Answer 25

place at which sister chromatids are joined in a replicated chromosome

Question 26

prophase

Answer 26

chromatids condense and recoil
centosomes move to poles of cell by microtubules and produce spindle fibres
nucleoili dissapears

Question 27

metaphase

Answer 27

chromosomes line up on equator

Question 28

anaphase

Answer 28

sister chromatids pull away
shortening microtubules
pole to pole lengthening

Question 29

telophase

Answer 29

daughter chromosomes reach seperate poles
spindle fibres break down
nucleur membrane form
2 nuclei form
daughter chromosomes unwind
no longer visible

Question 30

what do gametes need to be

Answer 30

contain 1 member of each homologous pair
be genetically different to increase variation
achieved by crossing over & independant assortment

Question 31

when does crossing over occur

Answer 31

in Prophase 1

Question 32

what is crossing over

Answer 32

2 homologous chromosomes join in bivalent sections of 1 chromosome and cross over with corresponding bits of the other chromosomes

Question 33

What happens in Prophase 2

Answer 33

chromosomes in nuclei of 2 daughter cells condense
become visible
nucleur envelope breaks down

Question 34

Which division is a reduction division

Answer 34

2nd division
homologous pairs are seperated going from diploid pairs 2n to haploid no pairs n cells