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diploid

two copies of every chromosome (2n), one from each parent

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rapid and effective reproduction that makes clones of the parent. any genetic variations are due to mutations or errors. prokaryotes do this (binary fission) and eukaryotes can do this too

asexual reproduction

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one copy of every chromosome (n=23 in people), one homolog from each pair. gametes.

haploid

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ori (origin)

region of chromosome. where replication starts

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diplontic life cycle

animals and plants life cycle, gametes are only haploid stage. then it fuses to form diploid in fertilization. all other stages and all cells are diploid.

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cell cycle

the time from one cell division to the next cell division. 2 phases in eukaryotes: interphase (long G1, S, G2) and M phase (mitosis and cytokinesis)

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metaphase

3rd phase of mitosis. chromosomes line up at midline (metaphase plate) of the cell

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point where genetic material is echanged between homologous chromosomes

chiasmata

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occurs during anaphase 1, it is a matter of chance as to which chromosomes (maternal or paternal) go to which daughter cell / gamete.

independent assortment

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fertilization

process where two haploid gamtes fuse to form a zygote during sexual reproduction

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replicates DNA. part of cell division. only occurs in S phase (synthesis)

replication

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interphase

part of cell cycle. in between rounds of mitosis. longest part. chromatin is not condensed (DNA loosely wrapped around protein histones). includes G1 (normal cell job), S (DNA replication), G2 (preparing for mitosis)

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astral microtubules

type of microtubules in spindle. interact with cell membrane and help keep poles apart

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4th phase of meiosis. separating homologous pairs into chromosomes that to opposite poles

anaphase I

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a meiosis error. if a homologous pair or chromatids do not separate at anaphase I or II. this causes aneuploidy

nondisjunction

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important for reproduction, growth and repair of tissues. 4 events: reproductive signal, replication, segregation and cytokinesis

cell division

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chromatid, sister chromatids

half of a chromosome. every chromosome has 2. this is a molecule of DNA. connected by centromere at center. made when chromosome is replicated in S phase

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centrioles

2 of these make up centrosomes. these are hollow tubes formed by microtubules

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1st phase of meiosis. can last a long time (decades in females, month in males). chromatin condenses. difference - homologous chromosomes pair up (synapsis). this forms a tetrad (4 chromatids). these homologs cross over at chiasmata

prophase I

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centrosome

in prophase, poles where chromosomes are moved to. one at each end of the cell

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chromosomes

condensed and compact chromatin that appear during prophase. they get wrapped tightly! composed of two chromatid

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region where chromatids are joined together

centromere

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cytokinesis

division of cytoplasm and separation of the two new cells. with a contractile ring. part of cell division. happens after mitosis in M phase

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interphase

long part of cell cycle. G1 (gap 1), S (DNA synthesis / DNA replicates) and G2 (gap 2)

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minus end-drected motor protein at kinetochores. move chromosomes along microtubules towards poles by hydrolyzing ATP for energy or microtubules shortening

cytoplasmic dynein

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centromere

region where chromatids are joined together

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in prophase, poles where chromosomes are moved to. one at each end of the cell

centrosome

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protein structures on centromere. microtubules attach here. important for moving chromosomes

kinetocore

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type of microtubules in spindle. attach to kinetochore on chromatids to pull chromatids apart

kinetochore microtubules

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anaphase I

4th phase of meiosis. separating homologous pairs into chromosomes that to opposite poles