B5: cell division

interphase

G1, G0, S, G2

karyokinase

division of genetic material

cytokinesis

division of cell itself

gap phase 1 (G1)

cell grows in preparation for cell division & checks for favorable conditions; favorable cell proceeds to the S phase

G0

cell still carries out functions, but not preparing for division (resting)

synthesis phase (S)

cell replicates its genome & centrosome

genome

all DNA in cell

centrosome

organelle that aids in cell division

gap phase 2 (G2)

organelles replicated & DNA assessed for errors, checks mitosis promoting factor (MPF) aka maturation promoting factor levels; a sufficient amount is needed to proceed to M phase (cell division)

centrosome

MTOC in animal cells; replicate during S phase so each daughter cell gets one

cilia & flagella

made up of 9 microtubule doublets w 2 signals in the center (9 + 2 array)

polar

connect centrosomes & push them to opposite sides of the cell

astral

attach to cell membrane & orient centrosome

kinetochore

attach to kinetochore on chromosome

functional limitations

physical reasons why cells need to divide once reaching a certain size

surface to volume ratio (S/V)

cell volume becomes too large for the surface area of their plasma membrane to support; decrease in S/V leads to division

genome to volume ratio (G/V)

cell volume becomes too large for the genome to support; decrease in G/V leads to cell division

G1 restriction point

conditions are favorable to grow & eventually divide

end of G2

accurately replicated genome, sufficient MPF levels

M checkpoint

microtubules properly attached to chromosomes

cyclin dependent kinases (CDK’S)

phosphorylate certain molecules in order to signal cell cycle progression

growth factors

bind plasma membrane receptors to signal growth & cell division

anchorage dependence

cells divide only when attached to an external surface

density dependent inhibition

halting of cell division when cell division is too high

chromatin

loosely winded DNA & protein complex

chromosome

separate DNA molecules that make up the genome

sister chromatids

identical copies of the same chromosome d

dyad

identical sister chromatids joined to form an X shape

centromere

region connecting sister chromatids in dyad

kinetochore

protein that associate with microtubules in cell division

prophase

DNA begins condensing into chromosomes, spindle apparatus forms, nuclear envelope begins to disappear, nucleolus disappears

metaphase

chromosomes line up along the metaphase plate attached to spindle fibers at their kinetochores

prometaphase

prior to metaphase, nuclear envelope fragments & spindle apparatus attaches to kinetochores

anaphase

kinetochore microtubules shorten causing sister chromatids to separate

telophase

chromosomes begin decondensing, nuclear envelopes reforms, cytokinesis begins

cytokinesis

cells divides resulting in 2 daughter cells

ploidy

the # of chromosome sets in the body

haploid

containing one set of chromosomes

diploid

containing 2 sets of chromosomes, one from each parent

homologous chromosomes

2 different copies of the same chromosome in a diploid organism

meiosis I

sister chromatids separate

somatic cells

body cells that are diploid , 2n = 46

germ cells

can divide via mitosis to form more diploid germ cells, or via meiosis to form haploid gametes

gametocytes

are eukaryotic germ cells

gametes

sperm & eggs are haploid, n = 23

prophase I

DNA condenses into chromosomes, homologous pair up & recombination occurs; spindle apparatus forms

synapsis

homologous chromosomes pair up to form tetrads (aka bivalents)

synaptonemal complex

protein structure that forms between homologous chromosomes during synapsis

chiasmata

site of crossing over leads to generic recombination

metaphase I

homologous chromosomes line up at the metaphase plate

anaphase I

homologous chromosomes are separated

telophase I & cytokinesis

the cytoplasm divides & 2 haploid cells form; each chromosome is composed of 2 sister chromatids

prophase I

DNA condenses into chromosomes; spindle apparatus forms

metaphase I

chromosomes line up aft the metaphase plate

anaphase I

sister chromatids are separated

telophase I & cytokinesis

the cytoplasm divides & 4 haploid daughter cell forms