Cell Division Flashcards
what is the cell cycle and its stages
regulated cycle of division and intermediate growth periods
interphase
mitosis/meiosis
cytokinesis
outline what happens during interphase
G1-synthesises proteins for replication and cell size doubles
S-DNA replicates
G2- organelles divide
what is the purpose of mitosis
produce two genetically identical daughter cells
growth
cell replacement
asexual reproduction
name the stages of mitosis
Prophase
Metaphase
Anaphase
Telophase
outline what happens during prophase
chromosomes condense
centrioles move to opposite poles of cells and mitotic spindle fibres form nuclear envelope and nucleolus break down-chromosomes free in cytoplasm
outline what happens during metaphase
sister chromatids line up at equator attached to spindle fibres by centromeres
outline what happens during anaphase
spindle fibres contract-centromeres divide
sister chromatids separate into 2 distinct chromosomes and pulled to opposite ends of cell
spindle fibres break down
what happens during telophase
chromosomes decondense
new nuclear envelope forms around each set of chromosomes
2 new nuclei
what happens during cytokinesis
cell membrane cleavage furrow forms
contractile division of cytoplasm
how is cell cycle regulated
checkpoints ensure damage detected and do not progress
what happens at G1 checkpoint
checks for DNA damage
what happens at G2 checkpoint
checks chromosome replication
what happens at metaphase checkpoint
cell checks sister chromatids have attached to spindle correctly
what is meiosis
produces four genetically different haploid cells
what happens during meiosis 1
homologous chromosomes pair to form bivalent
crossing over occurs at chiasmata
cell divides into two
homologous chromosomes separate randomly