UNIT 2 (topic 2) cell division Flashcards
what is the order of the cell cycle
- interphase (1st growth phase, synthesis, 2nd growth phase)
- mitosis (prophase, metophase, anaphase, telophase
explain interphase
- chromosomes are replicated (dispersed so are not visible)
- increased store of ATP
- produces lots of proteins
explain the stage prophase
- chromosomes condense
- nuclear envolope breaks down
- centrioles move to the poles of the cell and forms spindle fibres
what is a centriole
tiny protein organelle that makes and organises spindles
explain the stage metaphase
- spindle fibres attach to the centromeres and line up at the equator
- line up individually - no homogoulous pairs
explain the stage anaphase
- spindles contract
- centromeres divide, sister chromatids are seperated and pulled to one side
- each pole has one copy of original
explain the stage telophase
- chromosomes reach poles of the cell
- spindles break down
- nuclear envolopes reform around each group of chromosomes
- chromosomes disperse
what is binary fission
cell division of bacteria cells to produce 2 daughter cells
explain cytokinesis
the division of the cell membrane and cytoplasm
explain the 1st growth phase in interphase
daughter cells grow and complete normal cell activities
explain the synthesis phase in interphase
synthesises the DNA ready for cell division
explain the 2nd growth phase in interphase
organelles will divide
what could occur between the 1st growth phase and synthesis
GO ‘rest phase’ cells often stop dividing once differentiated
- may remain in rest stage for the rest of the lifetime or stay in temporarily
how do you find the mitotic index
number of cells going through mitosis divided by the total amount of cells
how would changes to the cell cycle lead to cancer
cells that should be stable begin to divide, forming a tumour
