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mitosis and the cell cycle (strand 2) - Coggle Diagram
mitosis and the cell cycle (strand 2)
interphase
normal cell activity occurs, cell isn't dividing and is preparing for division
cell synthesises new cell components, organelles and DNA
DNA is self replicating (semi conservative), after replication two copies of DNA remain attached at the centromere
chromosomes not visible, DNA exists as long threads called chromatin
prophase
chromosomes now condense and become visible
the chromosomes are made up of two chromatids joined by a centromere, the sister chromatids are identical copies of DNA from the parent cell 3. the two centrioles move apart producing spindle fibres made of microtubules and migrate to the poles 4. at the end of this phase the nuclear membrane breaks down and the nucleolus disappears
metaphase
1.the nuclear membrane has gone
the chromosomes arrange themselves on the equator of the spindle
spindle fibres from the poles attach to the centromere
anaphase
centromeres divide into two as spindle fibres pull individual chromatids apart
chromatids move to the poles and are now known as chromosomes
mitochondria gather round the spindle
telophase
chromosomes reach their poles and start to uncoil and become longer and thinner until they aren't visible and become chromatin
spindle fibres disintegrate, two distinguishable nuclear envelopes reform, nucleolus reforms
cytokinesis is beginning
cytokinesis
cytoplasmic division is achieved and two daughter cells are produced
protein filaments and microtubules are involved in the final stages of pulling these apart
required practical 2
heat 1 mol dm-3 HCl at 60°C in a water bath.
cut a small sample of the root tip using a scalpel
transfer root tip to HCl and incubate for 5 minutes.
remove from HCl and wash sample in cold distilled water
and remove the very tip using a scalpel
place tip on a microscope slide and add a few drops of stain, this makes the chromsomes visible and will therefore show which cells are undergoing mitosis
lower the cover slip down carefully onto the slide, make
sure there are no air in the slide which may distort the
image, and that the coverslip doesn't slide sideways which could damage the chromosomes
place under objective lens and set magnification to the lowest magnification
use the coarse adjustment knob to move the lens down
to just above the slide
Use the fine adjustment knob to carefully re-adjust the
focus until the image is clear
to calculate mitotic index, cells undergoing mitosis must be counted (cells with chromosomes visible) as well as the
total number of cells