cell division

Question 1

3 reasons cell replication occurs

Answer 1

1. replacing dead cells (repair 2. growth and maitenance

Question 2

how do prokaryotes replicate

Answer 2

via binary fission

Question 3

what is prkaryotic binary fission

Answer 3

each cell becomes 2 identical copies, this is asexual reproduction

Question 4

3 main categories of the cell cycle

Answer 4

interphase, mitosis and cytokinesis

Question 5

what are the phases in mitosis

Answer 5

prophase, metaphase, anaphase, telophase (cytokinesis)

Question 6

what are the three phases in the interphase

Answer 6

gap 1, synthesis (gap 0), gap 2

Question 7

what happens in gap 1 (interphase)

Answer 7

period of cell growth, normal metabolism, duplication of organelles

Question 8

what happens during the synthesis stage (interphase)

Answer 8

near the end of interphase, chromosomes duplicate to form two chromtids that are held together at the centromere

Question 9

what happens during interphase gap 2

Answer 9

cell grows and prepares itself for mitosis, involves increasing the volume of the cytosol and synthesising proteins in preparation for mitosis

Question 10

what happens during prophase

Answer 10

chromosomes coil/condense and become visible, centrioles move apart to opposite poles and spindles begin to form, late prophase the nuclear membrane breaks down

Question 11

what happens during metaphase

Answer 11

chromosomes appear as two sister chromatids joined at the centromere, chromosomes line up at the equator, microtubules of spindle attach to centromeres

Question 12

what happens during anaphase

Answer 12

microtubules contract, pulling centromeres and chromotids apart and moving them towards centrioles at opposite poles. chromotids are now considered new chromosomes

Question 13

what happens during telophase

Answer 13

spindle fibers breakdown, nuclear envelope forms around each group of chromosomes and chromosomes unravel to become invisible again

Question 14

what happens during cytokinesis

Answer 14

the plasma membrane pinches in to seperate the two nuclei, cytoplasm is divided to form two new daughter cells

Question 15

what is cell cycle regulation

Answer 15

if errors are detected at checkpoints, the cell wither repairs itself or will undergo programmed cell death - apoptosis

Question 16

what does the g1 checkpoint verify

Answer 16

grown to correct size, synthesised enough protein for DNA replication, if DNA has been damaged during previous mitosiss and cell growth

Question 17

what does the g2 checkpoint verify

Answer 17

dna has replicated properly during the s phase, cell has enough resources for mitosis

Question 18

what does the metaphase checkpoint verify

Answer 18

formation of spindle fibers, choromsomes are lined up correctly

Question 19

where are the three checkpoints

Answer 19

g1 g2 and metaphase

Question 20

what can cause checkpoints to malfunction

Answer 20

mutagens/dna mutations or indivdual genetics

Question 21

what is apoptosis

Answer 21

programmed cell death

Question 22

what are the two pathways of apoptosis

Answer 22

mitochondrial and death receptor

Question 23

is apoptosis the only way cells can die

Answer 23

no e.g necrosis, damage by oathogens, physical injury

Question 24

what are capases

Answer 24

enzymes that digest cell contents

Question 25

what are the stages of apoptosis

Answer 25

1. capases are activated in the cell 3. cells shrinks - blebs and nucleus condenses 4. partition of cytoplasm and nucleus into apoptotic bodies which are engulfed by pphagocytosis