Cell Cylce Flashcards
What are the stages of the cell cycle
Interphase: g1,s, g2
Mitosis: prophase, metaphase, anaphase, telophase
Cytokinesis
Describe interphase
Stage between divisions and takes up most of the time of the ill cycle. It consists of 3 parts:
Gl phase: first ‘gap’ phase, cell increases in mass and no. of organelles
S phase: DNA replication occurs and chromosomes are duplicated
G2 phase: second gap phase, all ATP synthesised for the remainder of the cell cycle
Describe prophase
Nucleolus disappears and chromosomes shorten and thicken to appear as 2 sister chromatids, joined by a centromere.
Each chromatid has a region in the centromere called 9 kinetochore made of motor proteins
Describe metaphase
Nuclear membrane disintegrates, bundles of microtubules extend from each pole to equator, microtubules attach to centrome of rain chromatid
Chromatids now aligned on metaphase plate, chromatids use kinetochore protein meters to walk up their microtubules to the poles
Describe anaphase (separating)
Kinetochore proteins drag chromatids to opposite poles of the cell by walking up the microtubules, chromatids begin to uncoil whilst being drawn up
Polar microtubules lengthen and make the distance between the poles bigger
Describe telophase (restoration)
Chromatids have reached the poles and the nuclear membrane reforms to enclose the identical groups of chromosomes
Golgi and vesicles reassemble and nucleoli reappear.
Cytokinesis also completes
Describe cytokinesis
Cytoplasm divides by a ring of contractile microfilaments encircling the cell
Cytokinesis also divides the number of organelles so both cells contain all organelles
Cytokinesis in plants
Line of vesicles form along the equator of cell merge to form 2 plasma membranes
Enzymes produced by these lay down the cell walls
Cytokinesis in animals
Ring of contractile microgitaments pull plasma membrane inwards, pinching cell in two, begins end of anaphase and continues through telophase
