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what are the three key things about bacterial cell division (BCD)?
asexual
genetic clone of parent cell
simplest form of cell division by prokaryotes
what is the name of the protien that forms the septum
FtsZ protien
what is the origin of replication
the first part of the DNA to be copied
what happens as replication continues?
the two origins move toward opposite ends of the cell, pulling the rest of the chromosomes along with them
what is an autosome
non-sex cell
what is a somatic cell
body cells
what is haploid
one set of chromosomes
what is diploid
two sets of chromosomes
what is a homologous pair
a pair of chromosomes with the same trait
what is the ratio of DNA and Protien in chromatin
40% DNA
60% protein
what is a chromosome
structure of nucleic acid and protien
what is a chromatin
single strand of chromosomes
what happens in the G1 phase
cell growth
what happens in the S phase
DNA, chromosome, centrosome replication
what happens in the G2 phase
organelles replicate, microtubules organize
what are the steps of mitosis
prophase
prometaphase
metaphase
anaphase
telophase
what is cytokinesis
separation of two new cells
what is a centromere
point of constriction
kinetochore
attachment site for microtubules
cohesin
protien that keeps chromosomes together
what happens in prophase
assembly of spindle apparatus
nuclear envelop starts to break down
two centrioles move to opposite poles forming spindle apparatus
what happens in prometaphase
complete breakdown of nuclear envelope
mitotic spindle apparatus fully takes over cell
each sister chromatid is connectd to opposite poles
chromosomes begin to move to the center of the cell
what happens in metaphase
alignment of chromosomes along the metaphase plate
what happens in anaphase
breakage of centromere
removal of cohesin proteins from all chromosomes
sister chromatids pulled to opposite poles
what is anaphase A
kinetochores pulled towards poles
what is anaphase B
poles move apart
what happens in telophase
each sister chromatid become a chromosome
nuclear membrane reforms
spindle apparatus disassembles
what happens in cytokinesis
cleavage of cell into equal halves
what is the ploidy all throughout mitosis
2n
when does the c value change
depending on the states of the chromosomes (replicated or unreplicated)
What happens in prophase 1
chromosomes coil together and become visible, nuclear envelope disapears, spindle forms
when does synapsis occur
early prophase 1
what is crossing over
genetic recombination between non sister chromatids
what is the chiasmata
site of crossing over
what happens in metaphase 1
paired homologues together following crossing over
microtubules from opposite poles attach each homologue
do not attach to each sister chromatid as in mitosis
homologues are aligned at the metaphase plate side by side
what is independent assortment
orientation of each pair of homologues on the spindle is random
what happens in anaphase 1
microtubules of the spindle break down
chiasmata break
homologues are separated from each other and move to opposite poles
sister chromatids remain attached at centromeres
independent assortment of maternal and paternal chromosomes
what happens in telophase 1
nuclear envelope reforms around each daughter cell
homologous chromosomes are separated
what happens in prophase ll
new spindle apparatus forms in each cell
nuclear envelope breakdown
what happens in metaphase ll
chromosomes consisting of sister chromatids joined at the centromere align along the metaphase plate in each cell
what happens in anaphase ll
kinetochore microtubules shorten
sister chromatids (non homologues) are pulled to the opposite poles of the cells
what happens in telophase ll
nuclear membranes re-form around 4 different clusters of chromosomes
what is the result of telophase ll
4 haploid cells
non disjunction
failure of chromosomes to have opposite pole during either mitotic division
aneuploid gametes
gametes with missing or extra chromosomes
how does down syndrome happen
results from the presence of an extra copy of chromosome 21