M phase

Question 1

prophase

Answer 1

• chromosomes that have replicated in the S phase of interphase consist of two identical sister chromatids which now shorten and thicken as the DNA supercoils
• the nuclear envelope breaks down
• the centriole in animal cells divides and two new daughter centrioles move to opposite ends of the cell
• cytoskeleton protein tubulin threads form a spindle between the centrioles, the spindle has a 3D structure and is like lines of longitude on a virtual globe, in plant cells the tubulin threads are formed from the cytoplasm

Question 2

Metaphase

Answer 2

• the pair of chromatids attach to the spindle threads at the equator region
• attach by there centromeres

Question 3

Anaphase

Answer 3

• the centromere of each pair of chromatids split
• motor proteins walk along the tubulin threads and pull each sister chromatid of a pair in opposite directions towards opposite poles
• because the centromere goes first the chromatids now called chromosomes assume a V shape

Question 4

Telophase

Answer 4

• separated chromosomes reach the poles
• new nuclear envelope forms around each set of chromosomes
• the cell now contains two nuclei each genetically identical to each other and to the parent cell from which they arose