mitosis

Question 1

Define mitosis

Answer 1

a type of cell division in which two daughter cells have the same number of chromosomes and are genetically identical with each other and the parent cell

Question 2

list the stages of the cell cycle

Answer 2

1) interphase
2) mitosis
3) cytokinesis

Question 3

What are the substages found in interphase

Answer 3

1) Gap 1 - G1
2) synthesis - S
3) Gap 2- G2

Question 4

describe what occurs during the G1 stage of interphase

Answer 4

1) proteins synthesis
2) organelles increase rapidly
3) mitochondria and chloroplasts replicate

Question 5

describe what occurs in the S stage of interphase

Answer 5

1) DNA replication = two times the amount of DNA but the same number of chromosomes

Question 6

describe what occurs in the G2 stage of interphase

Answer 6

1) proteins needed for cell division are synthesised

2) ATP synthesis increases

Question 7

what are the stages of mitosis

Answer 7

1) prophase
2) metaphase
3) anaphase
4) telophase

Question 8

outline what occurs in prophase of mitosis

Answer 8

1) chromosomes condense- they coil and shorten becoming thicker, they become visible as long threads
2) each centriole moves to opposite poles of the cell
3) protein microtubules ( spindles) form from each centriole extending from one centriole to the next
4) towards the end of prophase the nuclear envelope and nucleolus disappears

Question 9

outline what occurs in metaphase of mitosis

Answer 9

1) chromosomes attach to spindle fibres at their centromere and align at the equator- forming a line when the cell is viewed from the side

Question 10

outline what occurs in anaphase of mitosis

Answer 10

1) the microtubules contract splitting the centromere in two and pulling the chromatids to separate poles centromere first
2) chromatids are now called daughter chromatids

Question 11

outline telophase of mitosis

Answer 11

1) chromatids reach opposite ends of the pole and are known as chromosomes again
2) chromosomes uncoil and lengthen
3) the spindle fibres breakdown
4) nuclear envelope reforms
5) the nucleolus reappears

Question 12

describe cytokinesis

Answer 12

cytoplasm divides to produce two identical daughter cells

Question 13

what is are the differences in cell cycle between animals and plants

Answer 13

1) plant cells don’t have centrioles

2) during cytokinesis of plant cells a cell plate is formed across the equator for seperation

Question 14

what is the significance of mitosis

Answer 14

1) chromosome number
2) growth/repair of damaged tissues
3) asexual reproduction
4) cell replacement

Question 15

explain why the significance of mitosis in terms of chromosome number

Answer 15

• mitosis produces two daughter cells with the same number of chromosomes as the parent cell and each other
• therefore mitosis produces cells that are genetically identical to the parent providing genetic stability

Question 16

explain the significance of mitosis in terms of growth/ replacement/repair

Answer 16

• by producing new cells the organism can increase the cell number and grow, repair tissues and replace dead cells
• in embryos body cells are produced by mitosis
  some tissues such as skin become worn away, mitosis replaces lost cells
• production of new red blood cells/ white blood cells

Question 17

explain the significance of mitosis in terms of asexual reproduction

Answer 17

• produces genetically identical offspring to the parent

- takes place in unicellular organisms and some flowering plants