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21 Cards in this Set
- Front
- Back
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Chromosomes
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• Contained in the nucleus of every cell
• Specific number per species • Made up of DNA (deoxyribonucleic acid), a large molecule, shaped like a double helix • Carries genetic information encoded in genes • Genetic blueprint causing each individual to be different |
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Genes
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– discrete unit of hereditary information
– chromosome region – specific sequence of nucleotides |
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Fertilization
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• Diploid cell formed from fusion of haploid cells
• Thus reduction division imperative so chromosome number does not increase |
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Ploidy
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Number of homologous sets of chromosomes in a cell
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Homologous Chromosomes
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• Chromosomes with the same morphology and same genes
• 1 set from each parent |
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Alleles
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– An alternate form of a gene
– Is found at the same location on homologous chromosomes – Structural variations may lead to different phenotypes (how the organism looks) for a given trait |
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Asexual Reproduction
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Reproduction through cloning
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Sexual Reproduction
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offspring produced by joining of chromosomes of 2 parents
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Advantages of sexual reproduction
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• Produces genetic variation
• When faced with variability in the environment, populations with high degree of genetic variability have an increased chance of survival |
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Evolution
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Change in allele frequency in a population
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Prophase 1
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Meiosis phase in which homologous chromosomes pair to form tetrads; crossing over; Tetrads condense, nuclear membrane dissolves, spindle appears
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Synapsis
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process of linking replicated homologous chromosomes together to form tetrad
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Crossing Over
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where chromatids break and reattach to a chromatid on a different chromosome within the tetrad
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Metaphase 1
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Tetrads align on the equatorial plate (meiosis)
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Anaphase 1
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(meiosis) Chromatids seperate
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Telophase 1
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(meiosis) 2 nuclei form; end result: A reduction (in half) of the number of chromosomes
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Prophase 2
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(meiosis) Chromosomes re-condense, nuclear membrane dissolves,
spindle re-appears |
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Metaphase 2
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(meiosis)– Individual chromosomes composed of 2 chromatids align along the equatorial plate
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Anaphase 2
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(meiosis) chromatids seperate
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Result of Meiosis
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Four haploid gametes
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4 important facts about meiosis
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1.The result will be four (4) cells each with one half of the number of chromosomes as the original cell.
2.Each cell will have one (1) member of each homologous pair. 3.Which member of each homologous pair goes into a particular gamete is a matter of chance. |
