CELL AND NUCLEAR DIVISION Flashcards
what are the three stages of the cell cycle?
interphase nuclear division (mitosis) cell division (cytokinesis)
what are the stages of interphase?
G1
S
G2
what is interphase?
when the cell is metabolically active and is growing and copying chromosomes in preparation for cell division
what happens in G1 phase?
the cell is growing and producing new organelles
what happens in S phase?
replication of DNA
what happens in G2 phase?
preparation of the cell for mitosis like checking DNA for errors
what does a centromere do?
it hold the two sister chromatids together
what is mitosis and what are it’s stages?
nuclear division
four stages: prophase metaphase anaphase telophase
what happens in prophase?
chromosomes coil, condense and become visible
nucleolus disappears
nuclear envelope disappears
centrosomes form spindle fibers
what happens in metaphase?
chromosomes line up at the equator and attach to the spindle fibers by their centromeres
what happens in anaphase?
spindle fibers contract and centromeres divide and separate the sister chromatids
what happens in telophase?
chromosomes uncoil and become chromatin
nuclear envelope reappears
nucleolus reappears
spindle fibers disappear
what happens in cytokinesis in animal cells?
a cleavage furrow is formed and the two cells pinch off
what happens in cytokinesis in plant cells?
a cell plate forms between the divided nuclei and the cell plate gradually develops into a cell wall
what are the roles of mitosis?
growth
repair of damaged tissues
asexual reproduction; in bacteria eg.