Topic 2.3 Mitosis

Question 1

Metaphase

Answer 1

• chromosomes move to the equator and eventually line up along the plate
• each pair of chromosomes attach to a micro tubule of the spindle by the centromere

Question 2

Anaphase

Answer 2

• centromere splits
• sister chromatids are separated from each other
• each sister chromatid become individual chromosomes
• spindle fibres shorten and sister chromatids move further to poles

Question 3

Telophase

Answer 3

• separated chromatids (now chromosomes) reach poles
• new nuclear envelope form around the two sets of chromosomes
• spindle breaks down
• chromosomes uncoil and harder to see

Question 4

Cytokinesis - division of the cytoplasm

Animal cell

Answer 4

Animal cells: ring of contractile fibres tighten around centre of cell until the two cells separate

Question 5

Cytokinesis

Plant cell

Answer 5

-Starts with formation of cell plate where spindle equator was. New membrane and cell wall is made along cell plate. Vesicles packaged by Golgi are sent along microtubles to the centre of the cell. They carry (phospholipids and cellulose)

Question 6

Observing mitosis - meristem at a growing root tip

Answer 6

• Easy to observe mitosis in the cells of rapidly dividing tissues
• acetic orcein stains chromosomes
• temporary tissue squash preparation; separates cells to show the stages of mitosis

Question 7

Prophase

Answer 7

• chromosomes have replicated in interphase
• chromosomes condense, can take up stains and become visible
• Nuclear envelope breaks down
• centrioles begin two divide into two and move to opposite poles to form spindles