mitosis Flashcards
what does mitosis produce
two genetically identical daughter cells
what is the dna like in daughter cells of mitosis
an exact copy of the dna of a parent cell
what is mitosis needed for
growth of multicellular organisms and for repairing damaged tissues
draw the cell cycle including
mitosis
gap phase 1
synthesis
gap phase 2
mitosis- cell cycle starts and ends here
gap phase 1- cell grows and new organelles and proteins are made
synthesis- cell replicates its DNA ready to divide by mitosis
gap phase 2- cell keeps growing and proteins needed for cell division are made
what happens during interphase and is it before or after mitosis
interphase occurs before mitosis
- the cell carries out its normal functions but starts to prepare to divide
- cells dna is unravelled and replicated to double its genetic contents
- the organelles are also replicated so it has spare ones and its atp content is increased providing energy for cell division
what are the two chromosomes joined in the middle by
the centromere
what are seperate strands of chromosomes called
chromatids
what occurs in prophase
the chromosomes become shorter and fatter as they condense
-tiny balls of protein called centrioles start moving to opposite ends of the cell forming spindle fibres
- the nuclear envelope breaks down and chromosomes lie free in the cytoplasm
what occurs in metaphase
the chromosomes line up along the middle of the cell and become attached to the spindle by their centromere
what occurs in anaphase
the centromeres divide seperating each pair of sister chromatids
- the spindles contract pulling chromatids to opposite poles of the spindle
- makes the chromatids appear v shaped
what occurs in telophase
- the chromatids reach opposite ends on the spindle
- they unicoil and become long and thin again, they are now called chromosomes again
- the nuclear envelope forms around each group of the chromosomes so they are now two nuclei
- division of the cytoplasm ends in telophase
-there are now two genetically identical daughter cells - the daughter cells now begin interphase
what is the splitting of the cytoplasm called
cytokenisis
cancer is the result of uncontrolled cell division
explain how this happens-
1- mitosis and the cell cycle are controlled by genes
2- normally when cells divide enough times to make enough new cells, they stop but if theres a mutation in the gene that controls cell division the cells can grow out of control
3- the cells keep on dividing to make more and more cells which makes a tumour
4- cancer is a tumour that invades surrounding tissue
what does chemotherapy do to the cell cycle
prevents the synthesis of enzymes needed for dna replication.
- if these arent produced then the cell is unable to enter the synthesis stage disrupting the cell cycle and causing the cell to kill itself
what does radiation therapy do to cancer cells
damages dna at many parts of the cell cycle (including just before and during the S phase)
- the dna in the cell is then checked for damage and if there is severe damage then the cell will kill itself preventing further tumour growth.
