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BIO EXAM 3

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baejuhyeoned's version from 2017-08-09 12:49

CELL CYCLE CONTINUATION

 

Question Answer
Interphasethe DNA strand of a chromosome is copied and this copied strand is attached to the original strand at a spot called the centromere called a bivalent chromosome.
Monovalent chromosomechromosome exists as just one chromatid
bivalent chromosomeconsists of two sister chromatids
Late InterphaseChromatin is in its loosely coiled form
Late Interphasethe cell continues to grow and make proteins in preparation for mitosis and cytokinesis.
Early Prophasechromosomes start to condense
Early Prophase mitotic spindle begins to form and nucleus disappears
PrometaphaseMitotic spindle begins to capture and organize the chromosomes
Kinetochore a patch of protein found on the centromere of each sister chromatid
Centromeresare the regions of DNA where the sister chromatids are most tightly connected
Kinetochore microtubulesMicrotubules that bind a chromosome
Metaphasethe spindle has captured all the chromosomes and lined them up at the middle of the cell, ready to divide.
Metaphasetwo kinetochores of each chromosome should be attached to microtubules from opposite spindle poles
Spindle Checkpointthe cell will check to make sure that all the chromosomes are at the metaphase plate with their kinetochores correctly attached to microtubules
Spindle Checkpointhelps ensure that the sister chromatids will split evenly between the two daughter cells
AnaphaseThe sister chromatids separate from each other and are pulled towards opposite ends of the cell.
TelophaseThe mitotic spindle is broken down into its building blocks.
TelophaseThe chromosomes begin to decondense and return to their “stringy” form.
CytokinesisThe division of material outside of the nucleus
CytokinesisDivides the organelles and other substances in the cytoplasm into roughly two equal halves.
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MITOSIS MEIOSIS

Question Answer
(1) If the cell is short of nutrients, (2) If the DNA within the nucleus has not been replicated (3) If the DNA is damagedCheckpoints in the cell cycle will prevent cell division if
Meiosisthe production of gametes—sex cells, or sperm and eggs
Meiosisgoal is to make daughter cells with exactly half as many chromosomes as the starting cell.
Meiosisis a division process that takes us from a diploid cell—one with two sets of chromosomes—to haploid cells—ones with a single set of chromosomes
MeiosisProvides genetic variation in organisms
Meiosis IHomologue pairs separate during a first round of cell division
Meiosis IISister chromatids separate during a second round
Prophase Ithe chromosomes begin to condense, but they also pair up.
Prophase Ieach chromosome carefully aligns with its homologue partner so that the two match up at corresponding positions along their full length.
Crossing overProcess in which homologous chromosomes trade parts
Synaptonemal complexprotein structure that holds the homologues together.
ChiasmataCross over as seen on the microscope
Chiasmatacross-shaped structures where homologues are linked together
Chiasmatakeep the homologues connected to each other after the synaptonemal complex breaks down,
ChiasmataIt's common for multiple crossovers (up to 25!) to take place for each homologue pair
Metaphase 1the spindle begins to capture chromosomes and move them towards the center of the cell (metaphase plate).
Metaphase 1Each chromosome attaches to microtubules from just one pole of the spindle, and the two homologues of a pair bind to microtubules from opposite poles.
Anaphase Ihomologues are pulled apart and move apart to opposite ends of the cell. The sister chromatids of each chromosome, however, remain attached to one another and don't come apart.
Telophase Icmosomes arrive at opposite poles of the cell
Cytokinesisusually occurs at the same time as telophase I, forming two haploid daughter cells.
Meiosis IIshorter and simpler process than meiosis I
Meiosis II“mitosis for haploid cells."
Meiosis IIcells are haploid—have just one chromosome from each homologue pair—but their chromosomes still consist of two sister chromatids
Meiosis IIthe sister chromatids separate, making haploid cells with non-duplicated chromosomes.
Prophase IIchromosomes condense and the nuclear envelope breaks down, if needed. The centrosomes move apart, the spindle forms between them, and the spindle microtubules begin to capture chromosomes
Prophase IItwo sister chromatids of each chromosome are captured by microtubules from opposite spindle poles
Metaphase IIchromosomes line up individually along the metaphase plate
Anaphase IIthe sister chromatids separate and are pulled towards opposite poles of the cell
Telophase IInuclear membranes form around each set of chromosomes, and the chromosomes decondense.
Cytokinesissplits the chromosome sets into new cells, forming the final products of meiosis: fourhaploid cells in which each chromosome has just one chromatid. In humans, the products of meiosis are sperm or egg cells.
(1) Crossing Over & (2) Random orientation of homologue pairsHow meiosis "mixes and matches" genes?
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