Cell Cycle Flashcards
define mitosis
parent cell divides to produce 2 genetically identical daughter cells
each has exact copy of DNA from parent
lasts 1-2 hours
why is mitosis needed?
for the growth of multicellular organisms
repairing damaged tissues
asexual reproduction
what do NOT ALL cells in multicellular organisms do?
keep their ability to divide
what does the cell cycle consist of?
interphase (cell growth + DNA replication) G1, S, G2
mitosis
describe parts of cell cycle
M -> cycle starts + ends here, 1 parent cell divides into 2 daughter cells
G1 -> cell grows, new organelles + proteins made
S -> cell replicates its DNA ready to divide by mitosis
G2 -> cell keeps growing + proteins needed for cell division made
mnemonic for mitosis stages in order?
I-nterphase P-rophase M-etaphase A-naphase T-elophase C-ytokenesis
describe interphase
before mitosis
DNA unravelled + replicated
organelles replicated
ATP content increased -> gives energy for cell division
describe prophase
chromosomes condense -> get shorter + fatter
centrioles move to opposite sides of cell + form spindle fibres
nuclear envelope breaks -> chromosomes free in cytoplasm
describe metaphase
chromosomes line up in centre of cell + get attached to spindle fibres
describe anaphase
sister chromatids separated by spindle fibres to opposite poles
describe telophase
chromatids reach opposite poles
uncoil -> become long + thin -> now called chromosomes again
nuclear envelope forms around each group of chromosomes -> now 2 nuclei
describe cytokenesis
cytoplasm divides -> forms 2 genetically identical daughter cells
mitosis finished -> each daughter cell starts interphase to get ready for next round of mitosis
define mitotic index
proportion of cells undergoing mitosis
mitotic index equation?
no. of cells with visible chromosomes / total no. of cells observed
how many chromosomes do humans have?
46 -> 23 pairs
