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48 Cards in this Set

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S phase
DNA replication completed; Two sister chromatids joined together waiting to be segregated; "synthesis"
G2 phase
“gap” end of S phase to beginning of mitosis; Cell prepares for mitosis: i.e. Synthesize microtubules to move chromotids to opposite end of cell
Prophase
chromosomes condense and centrioles move to centrosomes. Centrioles produce microtubules in radial array.
Prometaphase
nuclear envelope disintegrates and kinetochore microtubules attach to kinetochore regions of chromosome. Chromosomes move toward poles
Polar microtubules
(prophase/prometaphase) microtubules that don't attach to kinetochore region. Forms framework of the spindle
Metaphase
chromosomes line up in middle (equatorial plate) of cell, one on top of the other. Mitotic spindle is fully formed
Anaphase
sister chromatids become separated and become chromosomes. Separation result of enzyme separase. Poles of spindle move apart as result of microtubules sliding by each other while kinetochore microtubules shorten.
Separase
Enzyme during anaphase that hydrolyzes cohesin that holds sister chromatids together @ centromere.
Motor action during anaphase
Poles of spindle move apart as result of microtubules sliding by each other while kinetochore microtubules shorten by removal of tubulin units. Motor proteins aid in motion of chromosomes.
Telophase
chromosomes reach poles. Nuclear envelope reforms around chromosomes. Chromosomes unwind.
Cytokinesis in animals
cleavage furrow (outside-in)--drawstring pull. Contraction of actin and myosin.
Cytokinesis in plants
cell plate formed (inside out). vesicles from Golgi apparatus fuse to form plasma membrane and contents contribute to cell plate.
Mitosis in fungi and some protista
1st nucleus divides then cell divides. Mitosis occurs within nucleus.
What are the 4 main checkpoints in regulating cell cycle?
G1/S, S, G2/M, late metaphase
protooncogenes
"before stimulate tumors"--genes that receive and respond to growth factors so that mitosis occurs; mutation of these genes may result in mitosis w/out growth factors :(
tumor suppressor genes
produce products that inhibit mitosis ex.: p21, p53, RB--if these genes don't work, mitosis not inhibited
Cyclin-dependent kinase (Cdk)
transitions from G1 to S and G2 to M depend on this protein; Cdk-cyclin complexes phosphorylate RB (inhibits the inhibitor of mitosis)
Cyclin
binds to Cdk’s and alters shape and exposes active site. After cyclins are produced, they're destroyed.
Retinoblastoma protein
normally inhibits cell cycle but when phosphorylated by protein kinase (Cdk-cyclin) becomes inactive and no longer blocks restriction point—G1—S phase
p21
gene that checks if DNA is damaged. Triggers enzymes to repair DNA by preventing formation of cyclin-cdk complexes. If irreparable, targeted for death.
S phase checkpoint
see if DNA properly replicated
G2/mitosis
check if preparations for mitosis completed
metaphase
check if all chromosomes attached to mitotic spindle
growth factors
in animals- stimulates cell division (even leave G0); they're usu. short peptides
another word for fertilization
syngamy
meiosis
cut # of chromosomes in half by cell division.
"diplontic life cycle"
only haploid cells are the ones produced by meiosis--animals
"haplontic life cycle"
most protists and many fungi: 2n stage is zygote which produce 1n spores which divide mitotically into organism--differentiates into sperm and egg
sexual life cycle of plants
alternating generations from gametophyte (1n) to sporophyte (2n)
gametophyte and sporophyte
(1) produces gametes by mitosis and (2) produces spores by meiosis
Meiosis I function
To reduce chromosomes by 1/2
Meiosis II function
create 4 daughter cells
Prophase I
homologous chromosomes undergo synapsis and crossing over of genetic material
tetrads or bivalents
4 chromatids or two chromosomes (describes homologous pairs undergoing synapsis)
chiasmata
crossing over and exchange parts of non-sister chromatids
prometaphase I
nuclear envelope fragments
Metaphase I
homologs line up on middle plate; maternal and paternal pairs align randomly (which way they face)
Anaphase I
homologous chrom. separate from each other--random arrg. basis of independent assortment
Telophase I
segregation of chromosomes into 2 clusters
cytokinesis
division of cell (usually)
Aneuploidy
wrong number of chromosomes--nondisjunctions during meiosis
nondisjunctions in anaphase I
2 gametes = n + 1
2 gametes = n - 1
i.e. two chromosomes in one side and 0 in the other
nondisjunctions in anaphase II
1 gamete = n + 1
1 gamete = n - 1
trisomic
n + 1 gamete creates 2n + 1 zygote--zygote is trisomic for a chromosome
monosomic
n - 1 gamete, 2n - 1 zygote
necrosis
cell killed by damage or starvation
apoptosis
programmed cell death--cell no longer needed or prone to genetic damage
instances of apoptosis
fetal development (webbed hands), respiratory tract and digestive tract (cells replaced every two weeks to kill off tumors)