mitosis + meiosis + cell cycle Flashcards
name the 4 phases of cell cycle
g1, synthesis, g2,m (mitosis)
which phase does the cells size increase
g1
which phase does the number of cells increase
m, they split
what is cancer
uncontrolled growth of cells, something in the cycle goes wrong (skips the growth part of the cycle)
which phase takes the longest
g1 (11 hours)
how can mistakes affect phase g1
no growth - no more cells can be made
how can mistakes affect phase s (synthesis)
cells won’t bond together
how can mistakes affect phase g2
there could be problems during mitosis
how can mistakes affect phase m (mitosis)
no other cells will be made
how can mistakes affect phase g0
bad, damaged cells will keep producing
describe interphase
dna has replicated, chromatin, membrane in tact
describe prophase
dna has shortened to condense into chromosomes, nuclear membrane and nucleolus not visible
describe metaphase
fibers attach to the centromeres of chromosomes, they align at metaphase plate
describe anaphase
spindle fibers shorten and centromere, separated sister chromatids,startsbeingpulled along
describe telophase
chromosomes reach the poles, spindle fibers descend
describe cytokinesis
last stage of mitosis, splits in half, furrows form, identical to parent cell
which phase of the cell cycle is the longest
interphase
which phase of the cell cycle is the shortest
telophase/cytokinesis
how many divisions of the cell and nucleus are in meiosis
2
what event takes place during interphase
growth and preparation for future stages
what two structures make up a single replicated chromosome
sister chromatids
when chromosomes forms a pair, what are they called?
tetrad
what stages of meiosis are haploid?
telophase 1
what stages of meiosis are diploid
metaphase 1 prophase anaphase
in meiosis 1 what structures separate during anaphase 1
homologous chromosomes
in meiosis 2 which structures separate during anaphase 2
sister chromatids
describe the cells at the end of meiosis 2
the cells have one copy of half of the genetic info in the original cell
what is the name given to the cells produced at the end of meiosis 1 in males
secondary spermatocyte
what is the name given to the cells produced at the end of meiosis 1 in females
oocyte
at the end of meiosis in males, what cells are produced
spermatids
what do spermatids eventually become
mature sperm
what ploidy is a zygote
diploid
what are the points called where the homologous pairs crossover
chiasma
what phrase is used to describe the chromatids after crossing over takes place and the homologous pairs separate
recombinant chromatids
homologous chromosomes def.
pairs of chromosomes, same size and shape and carry the same genes. (may carry different versions of genes called alleles)
where does meiosis go on
testes and ovaries - animals
anthers and ovules - floweing plants
diploid v haploid
diploid cells (2n) carry two copies of each chromosome, haploid cells (n) carry one copy of each chromosome, human diploid cells have 46 chromosomes; haploid cells (gametes) have 23
describe 1st meiotic division
homologous chromosomes pair up to form bivalents…tetrads, homologous chromosomes swap portions of chromatid at the chiasmata, homologous chromosomes separate during anaphase 1
describe 2nd meiotic division
4 cells produced at the end of telophase 2 (haploid gametes)
meiosis 1 - interphase
dna is replicated, each chromosome duplicates to become 2 sister chromatids, but hey are loosley coiled tonot visible yet
meiosis 1 - phrophase 1
nuclear envelope disintegrates, chromosomes start to become visible because the coil, shorten and thicken (condense), centrioles begin to make spindle fibres to move the chromosomes around, homologous pair up to form tetrads, they cross over
meiosis 1 - metaphase 1
tetrads move to the centre of the cell along protein tubules called spindle fibers, they line up on the equator of the spindle fibres
meiosis 1 - anaphase 1
spindle fibers contract and pull the chromosome pairs apart
meiosis 1 - telophase 1
chromosomes arrive at the poles of the cell, the cell divides into 2
meiosis 2 - prophase 2
chromosomes relax then condense again, a second set of spindle fibers forms at right angles to the spindle fibers in the first division
meiosis 2 - metaphase 2
chromosomes line up at the equator of the spindle fibers
meiosis 2 - anaphase 2
spindle fibers contract, centromeres split, and chromatids are pulled apart
meiosis 2 - telophase 2
chromosomes arrive at the poles of each cell, each cell divides into 2, four sex cells (gametes) are made
describe binary fission
cells grow to double their size and divide to form two cells
describe cellular differentiation
when a cell matures and develops, the unspecialized cells become specialized to execute a specific function (blood cells,skin cells, wtc.)
are cells identical after mitosis
yes
are cells identical after meiosis
no (goes from 46 to 23)
what does crossing over increase
genetic variance
yayy
yayy
