Mitosis Flashcards
what is mitosis
nuclear division that produces two genetically identical diploid daughter cells from one parent diploid cell
what occurs during interphase (G1 phase, S phase, G2 phase)
G1 phase -
chromosomes are unravelled allowing access to genetic material for:
new organelles are made so cells grow larger
enzymes are made for DNA replication
S phase -
cell replicates its DNA semi-conservatively
DNA content of cell doubles to ensure there is enough DNA to make new cells
G2 phase-
cell keeps growing and proteins needed for cell division are made (proteins needed for making spindle fibres, centrioles)
what occurs during mitosis (PMAT)
PROPHASE -
chromosomes condense (become shorter and thicker)
centrioles move to opposite poles of the cell and the spindles form ready to attach to the centromeres of the chromosomes
nucleus and nuclear envelope break down
METAPHASE -
chromosomes attach to the spindle fibres by their centromeres
chromosomes line up along the equator of the cell
ANAPHASE -
centromeres split which separates the two sister chromatids
spindle fibres shorten and contract which pulls the two chromatids to opposite poles of the cell
TELOPHASE -
chromosomes decondense (become long and thin again)
nuclear envelope forms around each group of chromosomes
cell has two nuclei at the end of telophase
two nucleolus form in each nucleus
spindle fibres break down
what occurs during cytokinesis in animal cells
cytoplasm divides
in animal cells a ring of protein filaments on the inside of the membrane contract and constrict to divide the cell
plant cells synthesises a new cell plate down the middle of the cell
how is the DNA structured inside the chromosomes (process)
DNA double helix
DNA, associated with histone proteins, winds around protein
DNA and proteins coil to form chromatin fibre
chromatin fibre attaches to a protein scaffold forming loops
the folding of the protein scaffold produces the condensed chromosome structure that is used during nuclear division
important features of mitosis
genetic consistency between multicellular organisms
old and damaged cells can be replaced by identical new copies
enables growth of one fertilised cell into a multicellular organism
cells can asexually reproduce
