Cell division Flashcards
what is mitosis
it a type of cell division that produces two genetic identical daughter cell for growth and repair of tissues
-one nuclear division
-diploid (2n)
what is meiosis
type of cell division that produce four non-identical cell that are called gametes
-two nuclear division ~ p mat happens twice
-haploid (n)
what is the cell cycle
interphase which consist of G1,S,G2
then mitosis happens
what is G1
the growth phase
-protein synthesis
-cell grow ~ organelles duplicate
what is G0
is the resting phase
-death (apoptosis)
- differentiation
-aging (senescence)
what is G2
more cell growth
what is S
synthesis of DNA
chromosomes form chromatids joined at centromere -semi conservative repelication
what is a checkpoint
places where DNA is checked for errors
to prevent uncontrolled cell divisions
to detect and repair damage to DNA
where are the checkpoint
G1/S -restriction point
G2/M
what are the stage of mitosis
prophase
metaphase
anaphase
telophase
what happens in prophase
chromosomes shorten, thickens and condense
2 chromatid joined by the centromere, the nucleolus and nuclear envelope disappear. the centrioles divide and move to opposite ends of the pole
what happen in metaphase
the pairs of chromatids attach to the spindle threads at the equator region they attach by their centromeres
what happen in anaphase
chromosomes separate at the centromere, chromatid move to opposite poles motor protein pulls the chromatids as it walks along the tubulin threads
what happens in telophase
chromatids become indistinct chromatin
nucleolus & nuclear envelope appears
cytokinesis ~cytoplasm divide
pinching of cytoplasm to form 2 cells
what is the purpose of meiosis 1
is to separate homologous pairs
what happens in prophase 1
homologous come together ~ bivalents
the non-sister chromatids join
the chromatid break then cross over ~creating new combination of alleles
what happens in metaphase 1
homologous chromosomes line up along the equator and attach to the
spindle fibre by their centromeres.
what happens in anaphase 1
homologous chromosomes are separated
what happens in telophase 1
chromosomes reach opposite poles of the cell. Nuclear envelope reforms
around the chromosomes. Cytokinesis results in the formation of two daughter cells.
what is the purpose of meiosis 11
is to separate sister chromatids
what happens in meiosis 11
Prophase II: chromosomes condense, nuclear envelope disintegrates and spindle fibres form.
Metaphase II: chromosomes attach to the spindle fibre by their centromeres.
Anaphase II: sister chromatids are separated.
Telophase II: chromatids reach opposite poles of the cell. Nuclear envelope reforms and cytokinesis takes places. Four genetically unique daughter cells are produce
what are the types of mutation
bad - embryos die
neutral - embryos aren’t affected
good - adaptation happens - evolution
(random fertilisation - sperm + egg -> zygotes)
