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22 Cards in this Set
- Front
- Back
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What are the four stages of the cell cyle/
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Mitosis, G2, S, G2
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Which three stages constitute interphase?
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G1, S, G2
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What is the shortest stage of the cell cycle?
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Mitosis
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Where are the two checkpoints in the cell cycle?
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G1, G2
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What occurs in G1?
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Everything except DNA is replicated
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What occurs during S phase?
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DNA synthesized
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What do N and C refer to?
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N = whether cell is haploid (1N) or diploid (2N)
C = number of chromatids (amount of DNA) |
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What is N and C for:
Diploid cell before copying its DNA Diploid cell after copying its DNA Haploid cell |
Diploid before: 2N, 2C
Diploid after: 2N, 4C Haploid: 1N, 1C |
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Describe the changes in N and C as a haploid cell undergoes meiosis.
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Parent cell: 2N, 2C-->2N, 4C
2N, 4C-->1N, 2C -->1N, 1C |
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What occurs during prophase?
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Chromatin condenses into chromosomes
Centrosome complex forms MTOC; splits in two, head to opposite poles Mitotic Spindle Formation |
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What occurs during prometaphase?
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Nuclear envelope disrupted
Nucleolus disappears Kinetochores assemble at each centromere on chromosomes Kinetochore MT's and Astral MT's form |
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What occurs during Metaphase?
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Chromosomes align at metaphase plate
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What would be the effect of colchicine on a cell during metaphase?
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Colchicine would inhibit microtubule formation and put cell under arrest
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In what stage of the cell cycle are chromosomes used for karyotype analysis?
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Metaphase: chromosomes are maximally condensed
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What occurs during anaphase?
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Kinetochores separate and chromosomes move to opposite poles
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What occurs during telophase?
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Chromosomes decondense, form chromatin
Nuclear envelope reforms |
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What occurs during cytokinesis?
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Cytoplasm divides via cleavage
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What cells make use of meiosis? What happens to N?
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Germ cells: goes from 2N (46 chromosomes) to 1N (23 chromosomes)
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How many rounds of DNA synthesis and division occur during meiosis?
What's the difference between Meiosis I and Meiosis II? |
One round of DNA synthesis followed by two rounds of segregation and cell division
MI: homologous chromosomes segregate to daughter cells MII: chromatids from each chromosome segregate to daughter cells Forms four haploid cells |
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What are the 4 subdivisions of prophase I of meiosis? What occurs in each?
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Leptotene:
Chromosomes already replicated Condensation begins Zygotene: Synapsis: homologous chromosomes pair closely; held together by synaptonemal complex Pachytene: Condensation of chromosomes continues Synapsis complete: each pair of homologs appear as bivalents (tetrads) CROSSING OVER TAKES PLACE Diplotene: Synaptonemal complex disappears; two components of tetrad (bivalent) separate Centromere of each homolog intact; chromatids held at chiasmata (location of crossover) |
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In what subdivision of prophase does crossing over occur?
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PACHYTENE
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What's the name of the region where on a chromosome where crossing over occurs?
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Chiasmata
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