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32 Cards in this Set
- Front
- Back
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How is cell division initiated?
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It's initiated by a reproductive signal.
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Name the three steps of cell division.
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Replication of DNA;
Segregation of two DNA molecules to separate portions of cell; Cytokineses, division of cytoplasm. |
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How is cell division in prokaryotes?
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Since dna is a single molecule, or chromosome it reproduces by fission.
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How is cell division in Eukaryotes?
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Eukaryotes divide by eighter meiosis or mitosis.
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What main phases do mitotic cell have?
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Interphase, cells not dividing.
Mitosis, cells are dividing. |
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Name the phases of Interphase.
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S, G1 and G2.
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G1
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1st step.
Cells not dividing, some cells stay here forever. |
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S
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2nd step.
Cells moving from G1 replicate their DNA during S-phase. |
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G2
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Waiting phase like G1, but cells do eventually divide.
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M
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Mitosis phase, nuclear division.
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Eukaryotic chromosome:
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-Contains DNA in chromatin.
-Durin M, replicated chromatin is held together at the centromere. -Each chromatin consist of double-stranded DNA molecule. |
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Chromatin.
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Complex where DNA is bound to a protein.
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During interphase:
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DNA in chromatin is wound around cores of histones(DNA) to form nucleosomes.
-DNA folds over and over packing itself inside the nucleus. -During mitosis or meiosis it folds even more. |
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Which phases do mitosis consist of?
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Interphase, prophase, prometaphase, metaphase, anaphase and telophase.
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Describe mitosis Interphase.
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During S phase of interphase the nucleus replicates its DNA and centrosomes.
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Describe mitosis Prophase.
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Chromosomes condense and spindle is developed.
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Describe mitosis Prometaphase.
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Chromosomes move towards the center of the cell, nuclear envelope breaks down.
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Describe mitosis Metaphase.
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Chromosomes move towards the center with their centromeres on the equatorial plate. At the end of Metaphase centromeres holding the sister chromatids together separate.
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Describe mitosis Anaphase.
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The daughter chromosomes move towards the their respective poles along the microtubule track.
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Describe mitosis Telophase.
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Chromosomes become less condensed, nuclear envelope and nucleoli reform, producing two nucleoli whose chromosomes are identical.
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Describe asexual reproduction.
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It produces organisms identical to its parent.
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Describe sexual reproduction.
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It produced organism that are the product of two gametes, one from each parent, thus making the organism genetically unique.
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Describe what a diploid cell is.
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It's a cell with 46 chromosomes.
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What is a haploid cell?
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A cell with 23 chromosomes.
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Where does meiosis happen?
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In testes and ovaries, in humans.
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Whats a gamete?
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A gamete is a haploid cell.
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How is a zygote made?
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With two gametes, one from each parent. 1n + 1n = 2n.
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Describe meiosis.
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It reduces chromosome number from diploid to haploid.
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Which phases do Meiosis consist of?
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It firstly consist of two nuclear divisions Meiosis I which consist of Prophase I, Metaphase I and Anaphase I; and Meiosis II which is practically a Mitosis.
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Describe Meiosis I Prophase I.
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Homologous chromosomes pair up with each other and cross over occur between the two homologs.
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Describe Meiosis I Metaphase I.
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Paired homologs line up at the equatorial plate.
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Describe Meiosis I anaphase I
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entire chromosomes, each with two chromatids migrate tot he poles, by the end of this phase there are two nuclei each with haploid number of chromosomes.
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