Mitosis, Meiosis, and Binary Fission

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