Cell cycle (mitosis/meiosis) Flashcards
how do prokaryotes divide
binary fission
how do eukaryotes divide
mitosis
is binary fission or mitosis faster
binary fission b/c there is less to copy
stages of interphase
G1, S-phase, G2
what is G1
stage of cell growth
what is s-phase
phase of DNA synthesis (copying)
what is G2
final growth and preparation for mitosis
what is G0 and where can it take place
a pause in interphase often within G1
what is a chromosome called after it is duplicated
a sister chromatid
difference between haploid and diploid cells
haploid=n
diploid=2n
difference in the number of sets of chromosomes within a cell
stages of mitosis
prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis
what happens during prophase
chromosomes condense, nuclear envelope starts to breakdown, spindle starts to form
what happens during prometaphase
nuclear envelope breaks down, chromosomes attach to microtubules and start moving to midzone
what happens during metaphase
chromosomes attach to microtubules and align at the metaphase plate
where is the metaphase plate
the middle of a cell
what happens during anaphase
the sister chromatids are separated and move to opposite poles of the cell
what happens during telophase
clean up
chromosomes decondense, nuclear envelope reforms, spindle fibers disappear
what happens during cytokinesis
division of the cytoplasm
when does cytokinesis begin
late anaphase or telophase
what is the mitotic spindle
refers to a complex protein structure made of microtubules for pulling apart chromosomes
what are kinetochore microtubules responsible for
moving chromosomes, the microtubule that physically connects to the chromosomes
what are the non-kinetochore microtubules responsible for
holding the spindle together and controlling its length
what are astral microtubules used for
spindle positioning (moving to the ends) and length control
what is the centromere
the constricted region of chromosomes linking the sister chromatids
center of the chromosome
what is the kinetochores
complex proteins on either side of the chromatids for the kinetochore microtubules to attach to
what happens to microtubules during anaphase a
kinetochore microtubules shorten and the chromatids move to the poles
what happens during anaphase b
non-kinetochore microtubules slide apart and the spindle elongates
what happens to the microtubules as the chromosomes move apart
they are disassembled as the chromosome moves up along it
what is the cleavage furrow
an indentation in the surface of a cell that forms during cytokinesis
why does the cleavage furrow form
b/c the contractile ring is cinching the membrane in until it pinches the two cells apart
cytokinesis in plants
vesicles fuse to form a cell plate and divide in to out
cytokinesis in animals
the contractile ring cinches from outside to separate the inside, divides out to in
why is meiosis important
genetic variation for evolution
what does meiosis create
gametes (sperm and egg cell), which are haploid cells
how do chromosomes mix
crossover sites called chiasmata once the chromosomes are connected/paired
what is synapsis
when homolog chromosomes pair up during meiosis
how are chromosomes in meiosis held together
by the synaptonemal complex
when does exchange/crossover between chromosomes happen
prophase
what does meiosis 1 result in
two haploid cells
what does meiosis 2 end with
4 haploid gametes
what is alternation of generations in plants
a life cycle pattern in plants where they alternate between two distinct phases: a haploid gametophyte stage and a diploid sporophyte stage
two different stages of their life cycles
what is sporic meiosis
the direct product of meiosis of 4 haploid spores (not gametes)
what is zygotic meiosis
when the zygote immediately does meiosis and does not grow at all
what happens if the cell cycle does not stop
creates a mass of abnormal cells called a tumor
why would cell division not stop
a damaged cell resulting in the signal to stop not being sent
difference between mitosis and meiosis
mitosis results in duplicate (exact twin) cells
meiosis results in 4 cell variations
