mitosis

Question 1

prophase

Answer 1

-chromatin condenses to become chromosomes
- two pairs of centrioles move to the opposite poles of the cell and spindle fibres are formed
-nuclear envelope disintegrates

Question 2

metaphase

Answer 2

• the two pairs of centrioles are positioned at opposite poles of the cell
• kinetochore spindle fibres pull on centromere, arranging the chromosomes in a single row on the metaphase plate

Question 3

anaphase

Answer 3

-spindle fibres attached to centromere shorten and contract, pulling the sister chromatid to the opposite poles of the cell
-centromeres divide and sister chromatids separate at centromere
-each sister chromatid become a daughter chromosome

Question 4

telophase

Answer 4

-daughter chromosomes pulled by spindle fibres attached to centromere reach opposite poles of the cell
-chromosomes uncoil, lengthen and become indistinct to form chromatin
-spindle fibres disintegrates
-nuclear membrane vesicles bind to the chromosome and fuse together

Question 5

difference between cytokinesis in an animal cell and plant cell

Answer 5

a cleavage furrow develops in an animal cell while cell plate formation occurs in a plant cell

Question 6

mitotic cell cycle in eukaryotes

Answer 6

mitosis produces genetically identical cells to:
-enable a multicellular organism to grow and develop into a single cell
-replace damaged and worn out cells, allowing for renewal and repair of tissues for asexual reproduction
-contribute to genetic stability

Question 7

role of centrioles

Answer 7

-centrioles organise the synthesis of spindle fibres which leads to a separation of chromatids during cell division
-the two pairs of centrioles move to the opposite poles of the cell and determine the polarity of the cell

Question 8

why does chromosome appear as double arm structure

Answer 8

-semi-conservative DNA replication occurs during S phase of interphase, producing two identical DNA molecules
- which coil and condense during prophase of mitosis to form a chromosome consisting of 2 identical sister chromatids held together at centromere

Question 9

tight control of mitotic cell cycle

Answer 9

-three checkpoints- G1 checkpoint, G2 checkpoint, M checkpoint
- ensure accurate completion of DNA replication
-prevent dysregulation of checkpoints of cell division, uncontrolled cell division which can lead to tumour formation and possibly cancer