Mitosis and the Cell Cycle Flashcards
What are the 4 stages of mitosis?
Prophase
Metaphase
Anaphase
Telophase
What 5 things happen in Prophase?
- the chromatin coils and condenses into chromosomes (2 sister chromatids joined at the centromere)
- nucleolus disintegrates
- nuclear envelope disintegrates
- centrioles move to poles
- centrioles produce spindle fibres
What 2 things happen in Metaphase?
- spindle attaches to chromosomes at the centromere
- chromosomes line up along the equator of the cell
What 2 things happen in Anaphase?
- chromosomes are separated
- 2 sister chromatids (now called chromosomes) move to opposite poles of the cell
What 5 things happen in Telophase?
- chromosomes ‘uncoil’ and turn back into chromatin
- nucleolus reforms
- nuclear envelope reforms
- spindle fibres detach
- spindle fibres disintegrate
Why are root cells used when investigating mitosis?
as root cells are growing, mitosis is happening as cells divide
Explain how to prepare a sample that can be used to investigate mitosis
- place root tips into HCl for 5 minutes, then rinse with water
- cut small, thin slices of a root
- place on slide and use mounted needle to spread thin layers of cell
- add a few drops of stain (e.g toluidine blue)
- place cover slip on
In which stage of the cell cycle is DNA replicated?
S
Describe how to calculate the mitotic index
cells undergoing mitosis/total number of cells x100
What might a high mitotic index suggest?
tissue repair/growth is occurring; possibly, tumours are developing (especially if in adult cells)
What is the name given to the division of cytoplasm?
cytokinesis
What is a tumour?
a mass of cells caused by uncontrolled cell division
How do cancer treatments work?
they re-establish control over the rate of cell division by disrupting the cell cycle and killing tumour cells
Describe binary fission in bacteria
- circular DNA is replicated
- plasmids are replicated
- division of cytoplasm to form daughter cells
Suggest and explain how two environmental variables could be changed to increase the growth rate of these cells
- increase in temp -> causes increased enzymes activity
- increase in [glucose] -> increased respiration
- increase in [oxygen] -> increased respiration
- increase in number of nucleotides -> increased DNA synthesis
Why would preventing the formation of spindle stop the cell cycle?
- centromeres would not attach to spindle fibres
- cannot be lined up, no metaphases
OR - CHROMATIDS could not be separated
- no anaphase
What are the 3 stages of the cell cycle?
mitosis, cytokinesis, interphase
Why is mitosis/the cell cycle important?
- growth
- repair
- reproduction
How do viruses replicate?
they do not undergo cell division, instead they infect host cells, and the host cells replicate viral proteins (and particles) for them
What happens in interphase?
cell grows, organelles replicate, DNA replicates, DNA is checked
How is mitosis controlled?
2 types of genes that speed up or slow down cell division
How many daughter cells are produced in binary fission?
2
