cell division Flashcards by Taylor Brennan

cell division

nuclear division followed by cytoplasmic division

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another name for nuclear division

karyokinesis

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another name for cytoplasmic division

cytokineses

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diploid cells have 2 copies of every chromosome forming…

homologous chromosomes

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how many chromosomes do humans have

46
(23 homologous pairs)

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animal cells have cellular structures called

centrosomes

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each centrosome contains a pair of

centrioles

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centrioles produce

spindle fibers that will separate sister chromatids during anaphase

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the cell cycle is divided into

interphase (G1, S, G2)
mitotic phase (mitosis + cytokinesis)

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interphase

begins after mitosis and cytokinesis are complete
(when cells are replicated and physically separated

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cell increases in size
G1 checkpoint ensures everything is ready for DNA synthesis
most cell growth in volume occurs here

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DNA synthesis
second molecule of DNA replicated from the first creating sister chromatids

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when is DNA replicated

S phase
NOT mitosis

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rapid cell growth continues to occur
preparation of genetic material for cellular division
cell replicates organelles

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inactive state of cells not actively growing or dividing

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what cells are examples of G0 (2)

nerve cells
cardiac cells

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surface area to vol ratio
SMALL

cellular exchange is hard
leads to cell death or cell division to increase surface area

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Genome to volume ratio
SMALL

as the ratio decreases the cell exceeds the ability of its genome to produce proteins needed to regulate the cell

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spindle apparatus forms when

during prophase

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what are crucial to cell division during mitotic phase

microtubules
mitotic spindle

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what do anti-tumor drugs act on in cancers?

act as microtubule inhibitors
the drugs stabilize microtubules preventing chromosome and chromatid separation and causing cell cycle arrest (no cell division)

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when does a virus impact the mitotic spindle

impacts the spindle most affects a cell during mitotic phase

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each sister chromatid has a

kinetochore
where microtubules attach - not chromosomes directly

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MITOSIS
prophase - chromosome and chromatids

46 chromosomes
92 chromatids

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MITOSIS prophase

nucleus disassembles nucleolus disappears chromatin condenses into chromosomes

MITOSIS metaphase - chromosomes + chromatids

46 chromosomes 92 chromatids

MITOSIS metaphase

chromosomes line up each metaphase chromosome consists of 2 attached sister chromatids each chromatid is complete with a centromere and attached kinetochore

MITOSIS Anaphase - chromosomes + chromatids

92 chromosomes 92 chromatids

MITOSIS Anaphase

microtubules shorten and each chromosome is pulled apart into 2 separate chromatids (once physically separated, each chromatid is considered a chromosome so the chromosome # has doubled) chromosomes pulled to opposite poles each pole has a complete set of chromosomes

disjunction

chromosomes pulled to opposite pole

MITOSIS telophase + cytokinesis - chromosomes + chromatids

92 chromosomes 92 chromatids

MITOSIS telophase + cytokinesis

nuclear envelope re-forms chromosomes decondense back into chromatin and nucleoli reappear

after cytokinesis how many chromosomes and chromatids in each cell

46 chromosomes 46 chromatids

meiosis produces (from 1 diploid parent cell)

4 non-identical haploid daughter cells

meiosis I

homologous chromosomes separate

meiosis II

sister chromatids separate

Prophase I chromosomes + chromatids

46 chromosomes 92 chromatids

prophase I

- spindles form and nuclear envelope breaks down - chromosomes pair up lengthwise forming tetrads which need to form for crossing over to occur - pairs are physically linked through chiasmata - microtubules attach to chromosomes at kinetochores and move them towards metaphase plate

synapsis

chromosomes pair up lengthwise in prophase I

where does crossover occur

chiasmata

metaphase I chromosomes + chromatids

46 chromosomes 92 chromatids

metaphase I

- homologous chromosomes are arranged at the metaphase plate - independent assortment of chromosomes occurs because the arrangement of homologous chromosomes is random

anaphase I chromosomes + chromatids

46 chromosomes 92 chromatids

anaphase I

homologous chromosomes separate and spindle apparatus guides the chromosomes to opposite poles

telophase I + cytokinesis chromosomes + chromatids

46 chromosomes 92 chromatids

telophase I + cytokinesis

- homologous chromosomes are separated from each other to each end of the cell - cytokinesis

cytokinesis I results in how many daughter cells

2 haploid daughter cells each contain 1 chromosomes from every homologous pair

prophase II chromosomes + chromatids

23 chromosomes 46 chromatids

prophase II

spindle apparatus forms and microtubules move chromosomes towards metaphase plate

metaphase II chromosomes + chromatids

23 chromosomes 46 chromatids

metaphase II

- sister chromatids are no longer genetically identical due to crossing over - chromosomes lined up at metaphase plate

anaphase II chromosomes + chromatids

46 chromosomes 46 chromatids

anaphase II

- chromatids separate moving towards opposite ends - separated chromatids are now chromosomes

telophase II + cytokinesis chromosomes + chromatids

46 chromosomes 46 chromatids

telophase II + cytokinesis

- nuclei formation and decondensing of chromosomes - cytokinesis

cytokinesis II results in how many daughter cell

4 genetically distinct daughter cells in total

3 sources of genetic variation

crossing over independent assortment random joining of gametes (which sperm fertilizes the egg)

crossing over

non-sister chromatids of 2 homologous chromosomes exchanging genetic material

when does crossing over occur

prophase I

independent assortment

random orientation of homologous chromosomes allows for the production of gametes with many different assortments of alleles

when does independent assortment occur

metaphase I

are genes closer together more or less likely to be inherited together