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38 Cards in this Set
- Front
- Back
Cell cycle must coordinate
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Growth of cell
Duplication of organelles Duplication of DNA Duplication of centrosomes (MTOC) Mitotic spindle apparatus Chromosome condensation/decondensation Chromosome separation Nuclear envelope breakdown/assembly Cytokinesis (cell division) |
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Cytokinesis
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cell division
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In the cell cycle, G1G2 stands for
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gap or growth
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In the cell cycle, S stands for
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DNA synthesis
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In the cell cycle, M stands for
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mitosis
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quiescence
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G0 phase where the cells are not dividing
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G1 + S + G2 =
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interphase
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In the cell cycle, R stands for
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restriction point
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hydrogen-3
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tritium, a radioactive isotope of hydrogen
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In the discovery of _____,
Radioactive tritium, or ³H, was incorporate into ______ |
S phase; thymidine
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Grow cells in ³H _____→ If DNA is replicated then ³H-T is incorporated into ____, and therefor the _____ becomes radioactive.
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thymidine ; DNA; nucleus
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Pulse-chase experiment
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1) Put a mixture of cells in ³H thymidine for 30' (thirty minutes), then wash away the ³H thymidine
2) After 1 hr only a subset of cells had radioactive nuclei. 3) After five hours a few labeled (labeled = tritium incorporated) cells have condensed chromatin (which is a sign of beginning to enter mitosis). 4) After 6 hours labeled cells enter mitosis. |
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Mitosis in a typical human cell takes ____ hours
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1-2
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G1 in a typical human cell takes ___ hours
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8 hours
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S in a typical human cell takes ___hours
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8 hours
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G2 in a typical human cell takes -___hours
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5 hrs
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What are the 6 Stages of mitosis?
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1) prophase,
2) prometaphase, 3) metaphase, 4) anaphase, 5) telophase, 6)cytokinesis |
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prophase
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chromosomes condense
Centrosomes migrate and begin to assemble the spindle |
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prometaphase
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nuclear envelope breaks down
Attach to the spindle |
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metaphase
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Chromosomes align at the equator
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anaphase
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sister chromoatids simultaneously separate and are puled slowly towards the spindle poles.
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telophase
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chromosomes at the poles begin to decondense
The nuclear envelope begins to reform |
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cytokinesis
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cells pinch in two by action of microfilaments and their motors
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Nuclear lamins
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found inside nuclear envelope and form meshwork
phosphates added and they fall apart. |
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Chromosome condensation
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DNA + proteins form chromatin
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nucleosome
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consist of 8 proteins call histones
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DNA wraps how many times around nucleosome?
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Two
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How many base pairs from the beginning of one nucleosome to the next.
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200
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Sister chromatids are held together at the _____
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centromere
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______hold chromatids together at the _____
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cohesins ; centromere
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Spindle apparatus
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microtubules coming out from each side, many of which overlap or come down and grab the end of the cell
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kinetochore
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a protein plaque at the centromere that captures mictrotubules
contains MT motor proteins |
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Astral microtubules
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grab edge of the cell
stick out towards edge of cell |
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Polar microtubules
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at middle-cell
come across and connect past the midpoint, overlapping. Often motor proteins that sit in between them that can push them apart. |
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microtubules that attach to kinetochore are called
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kinetochore microtubules
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Minus ends of microtubules are ____
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buried at the pole
Minus ends of MT in MTOC (microtubules organization center) |
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What's special about Drosophila eggs?
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12 cycles of nuclear division without cytokinesis
Rapid division of nuclei 20 – 30 minutes No G1 or G2, only M and S |
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What was done in the dropsophila egg experiment?
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Into the eggs he injected a chemical called DAPI (blue fluorescent that binds DNA)
Also injected tubulin labeled with green fluorescent |