MCB 2410: EXAM 1 CHAPTER 2
45 Cards in this Set
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Prokaryote
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a unicellular organism of relatively simple cell structure (pg. 17). Lack a cell nucleus.
Single CIRCULAR chromosome
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Eukaryote
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an organism with compartmentalized cell structure, with components bounded by intracellular membranes. Eukaryotes are either unicellular or multicellular
Multiple LINEAR chromosomes
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Nucleus
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the area enclosed by the nuclear envelope. The nucleus separates DNA from the other cellular content. A major difference between prokaryotes and eukaryotes is that prokaryotes do not have nuclei
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Histone
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a special class of protein with which DNA associates to form tightly packed chromosomes. Histone winding regulates the access enzymes have to genetic material
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Chromatin
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the complex formed by DNA and histones. It composes eukaryotic chromosomes
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Homologous Chromosomes
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two chromosomes, that are usually alike in structure, in size, and in the types of encoded traits
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Diploid
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a cell type that carries two sets of genetic information
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Haploid
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a cell type that carries one set of genetic information
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Telomere
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the tip of a whole, linear chromosome. It provides stability and protection to the chromosome
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Origins of replication
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the sites where DNA synthesis begins
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Sister Chromatids
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Two identical copies of a chromosome held together at the centromere. Each consists of a single molecule of DNA
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Cell Cycle
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the stages through which a cell passes from one division to the next
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Checkpoints
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Checkpoints function to ensure that all the cellular components, such as important proteins and chromosomes, are present and functioning before the cell moves to the next stage of the cell cycle. If components are missing or not functioning, the checkpoint will prevent the cell from movin…
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When do Checkpoints occur?
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These checkpoints occur throughout the various stages of the cell cycle. Important checkpoints include the G1/S checkpoint, which occurs during G1 prior to the S phase; the G2/M checkpoint, which occurs in G2 prior to mitosis; and the spindle-assembly checkpoint, which occurs during mitos…
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Interphase and M-phase
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the two major phases of the cell cycle. In interphase, the cell grows, develops, and functions. The M-phase consists of mitosis and of cytokinesis. In M-phase, the cell divides
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Mitosis
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division of a somatic cell—specifically, nuclear division. Produces offspring that are identical to the parent cell
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Cytokinesis
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Cytoplasmic division
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Prophase
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The chromosomes condense and become visible, the centrosomes move apart, and microtubule fibers form from the centrosomes. The nucleoli disappear and the nuclear envelope begins to disintegrate, allowing for the cytoplasm and nucleoplasm to join. The sister chromatids of each chromosome a…
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Metaphase
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The spindle microtubules are clearly visible and the chromosomes arrange themselves on the equatorial plane of the cell
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Anaphase
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The sister chromatids separate at the centromeres after the breakdown of cohesin protein, and the newly formed daughter chromosomes move to the opposite poles of the cell.
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Telophase
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The nuclear envelope reforms around each set of daughter chromosomes. Nucleoli reappear. Spindle microtubules disintegrate
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Meiosis
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the process through which gametogenesis occurs, and through which haploid gametes are produced
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Fertilization
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the other half of sexual reproduction (the first half is meiosis), in which haploid gametes fuse to restore the diploid number of chromosomes
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Meiosis I
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Separation of homologous chromosomes
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Prophase I
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The chromosomes condense and homologous pairs of chromosomes undergo synapsis. While the chromosomes are synapsed, crossing over occurs. The nuclear membrane disintegrates and the meiotic spindle begins to form.
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Metaphase I
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The homologous pairs of chromosomes line up on the equatorial plane of the metaphase plate.
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Anaphase I
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Homologous chromosomes separate and move to opposite poles of the cell. Each chromosome possesses two sister chromatids
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Telophase I
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The separated homologous chromosomes reach the spindle poles and are at opposite ends of the cell.
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Meiosis I is followed by cytokinesis,
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Resulting in the division of the cytoplasm and the production of two haploid cells. These cells may skip directly into meiosis II or enter interkinesis, where the nuclear envelope reforms and the spindle fibers break down.
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Meiosis II
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Separation of sister chromatids
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Prophase II
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Chromosomes condense, the nuclear envelope breaks down, and the spindle fibers form.
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Metaphase II
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Chromosomes line up at the equatorial plane of the metaphase plate.
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Anaphase II
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The centromeres split, which results in the separation of sister chromatids
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Telophase II
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The daughter chromosomes arrive at the poles of the spindle. The nuclear envelope reforms, and the spindle fibers break down
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Following meiosis II
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cytokinesis takes place
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Synapsis
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a close association of homologous chromosomes (four associated chromatids=tetrad or bivalent)
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Crossing Over
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homologous chromosomes exchange information after the formation of chiasma
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Recombination
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the creation of new allele combinations in gametes or on chromosomes via independent assortment and crossing over
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Cohesin
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a protein that holds sister chomatid strands together, and that holds homologous pairs together. It is critical to chromosome behaviors in Mitosis and Meiosis
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Spermatogenesis
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the production of gametes in the male animal
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Oogenesis
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the production of gametes in the female animal
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Oocyte
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an intermediate product of oogenesis that will eventually develop into the ovum. There are primary and secondary oocytes
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Metacentric, submetacentric, acrocentric, telocentric
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the centromere moves progressively closer to the end of the chromosome as we move from meta- to telo
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Dyad
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2 chromatids attached at the centromere
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Kinetochore
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the site where the sister chromatids attach
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MCB 2410: CHAPTER 3: MENDELIAN GENETICS