Required practical 2 Flashcards
Name the 3 key phases of the cell cycle:
Interphase (G1,S,G2), Mitosis, and cytokinesis.
What happens during prophase?
The chromosomes condense and become visible. In animal cells the centrioles seperate and move to opposite poles of the cell. The centrioles produce spindle fibres which form the spindle apparatus.
What happens during metaphase?
The chromosomes align along the equator. The spindle fibres released from the poles attach to the centromere and chromatid.
What happens during anaphase?
The spindle fibres retract back into the centrioles at the opposite poles. This causes the centromere to break in two and the individual sister chromatids are pulled to opposite poles. They are now referred to as chromosomes.
What happens during telophase and cytokinesis?
The chromosomes unwind back into chromatin and the nuclear envelope reforms. Two nuclei are present. Cytokinesis then takes place which produces two new genetically identical daughter cells.
Why is ATP needed for mitosis?
Anaphase requires ATP.
How to calculate mitotic index?
The number of cells in mitosis/total number of cells x 100
Why is the root tip used?
That’s where meristem tissue is present (actively in mitosis).
Why place root tip in hydrochloric acid?
To make the cells more permeable so the stain can bind to DNA.
Why macerate the root tip with a needle?
Ensures cells are thoroughly flattened and can be seen and stain can enter the cells.
Why push down hard and not sideways with the coverslip?
Push down hard so cells are spread and not sideways because that can cause chromosomes to break.
