Cell Division Flashcards
When a cell is not dividing, each chromosome exists in a single copy called a
chromatid
When the cell is preparing to divide, each chromosome must be replicated so that it contains –
2 chromatids (sister chromatids)
each chromosome has a compressed region
centromere
When the chromosomes replicate the – stay attached to each other at the centromere
sister chromatids
mitosis occurs in most cells except for –, –, –
gametes and mature never and muscle cells in animals
during G1, the parent cell is growing larger and is adding – and replicating –
cytoplasm, organelles
first gap phase of the cell cycle
G1 stage
phase of DNA synthesis when the chromosomes are all being replicated
S stage
Once – is complete, each chromosome will consist of 2 sister chromatids connected at the centromere
S stage
second gap phase
G2
During G2 the cell will continue to – and make final preparations for cell division
grow in size
mitosis occurs in this phase
M
division of the cytoplasm at the end of the M phase is
cytokinesis
interphase = G1, S, G2
preparation for cell division
examples of cells that lose the ability to undergo the cell cycle and thus cannot divid
mature human nerve and muscle cells
cells without the ability to divide are in the – phase where division will never resume
G0
chromosomes are located in the –
nucleus
prior to division, the chromosomes are not condensed and thus are –
not visible
leaving the chromosomes in an uncondensed state makes it easier to copy the DNA but makes the chromosomes very –
stringy and fragile
once the DNA is replicated, the chromosomes must condense so that they are not – as they are divided up into the two daughter cells
broken
chromosome condensation occurs, making the chromosome visible
prophase
During prophase, the – present in the cello replicate and move to opposite ends of the cell
centrioles
When the centrioles reach the poles of the cell, they begin to produce –
spindle apparatus
the spindle apparatus consist of spindle fibers that radiate outward forming –
asters
spindle fibers are made of – that will ultimately attach to each chromosome at the kinetochore
microtubules
kinetochore (protein structure) appears at the – of each chromosome
centromere
nuclear envelope and lamina is broken down by phosphorylation of the nuclear pore proteins and lamins
prometaphase
once the – breaks down, the spindle microtubules will attach to the chromosomes by binding to the kinetochore
nucleus
chromosomes align down the center of the cell
metaphase
there is a checkpoint in this phase
metaphase
centromere spits, allowing each chromatid to have its own centromere
anaphase
during anaphase, the chromatids can be separated and are pulled towards
opposite poles
chromatids are moved to opposite poles by – of the kinetochore microtubules
depolymerization
nuclear pore proteins and lamina are dephosphorylated in this phase because the spindle apparatus is no longer needed
telophase
during telophase, the – and – reform around each set of chromosomes
nuclear envelope and lamina
in animal cells, a – forms that pinches the cells apart from each other
cleavage furrow
in plant cells, a – made of cellulose divides the two daughter cells
cell plate
the end result of mitosis, is two daughter cells ready to begin – of their cell cycle
interphase
crossing over occurs in
prophase I
crossing over = homologous pairs of chromosomes associate and twist together in –
synapsis
the result of crossing over is two replicated chromosomes or a total of four chromatids called a
tetrad
T or F: crossing over can occur in more than one location and can unlink genes that were previously linked on the same chromosome
true
crossing over is an important source of genetic diversity, creating combinations of – that were not seen previously
alleles
in metaphase of mitosis, chromosomes align – down the center of the cell
single file
in metaphase I of meiosis, the chromosomes align as – down the center of the cell
pairs
law of independent assortment
the alignment of each member of the homologous pair during metaphase I is random giving a unique combination of maternal and paternal alleles
during anaphase I, – will separate from each other and be pulled to the poles of the cells
homologous pairs
the separation during anaphase I is referred to as –
disjunction
at the end of telophase I, each daughter cell is genetically unique and contains – number of the chromosomes of the parent cell
half
at the end of telophase I, the chromosomes are still in their – form, consisting of two chromatids
replicated
– split the chromatids present in the daughter cells produced during meiosis I
meiosis II
the events in this phase does not occur in all species
prophase II
metaphase II
chromosomes align down the center of the cell
anaphase II
sister chromatids are separated and move toward the poles of the cell
telophase II
nuclear envelopes reform and cytokinesis occurs to produce daughter cells
at the end of meiosis II, each daughter cell has a – copy of each chromosome
single
