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Genetics - Coggle Diagram
Genetics
Mutations: a mutation is any change, however large or small, in DNA
Crossing Heterozygotes with Themselves: When a plant's own pollen is used to fertilize its own eggs, the cross is a selfing.
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Test Crosses: We can only see an organism's phenotype; to discover its genotype, we must perform crosses, and the test cross is one of the most useful.
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Multiple Alleles : each gene may have many alleles, not just two as in the examples shown. A protein of average size consists of about 300 amino acids, so the coding portion of the mRNA must have about 300 codons, each containing three nucleotides.
Monohybrid Crosses: Only a single character is analyzed and studied, the inheritance of other traits is not considered.
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Dihybrid Crosses: one in which two genes are studied and analyzed simultaneously, rather than a monohybrid cross where there is just one gene. #
Crossing-Over: Independent assortment can also occur if the two genes are located far apart on the same chromosome such that crossing-over occurs between them during prophase I, after homologous chromosomes have paired and a synaptonemal complex is formed.
Genes on the Same Chromosome, Linkage: if two genes occur close together on a chromosome, they usually do not undergo independent assortment
Genes on Separate Chromosomes (Independent Assortment): If two genes are on separate chromosomes, the alleles of one gene move independently of the alleles of the other gene.
Multiple Genes for One Character: Individual phenotypic traits are the result of complex metabolic processes involving numerous enzymes; therefore, many separate genes may affect any single trait.
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Quantitative Trait Loci: Extremely complex crosses, involving hundreds or thousands of progeny, may have to be performed to determine what fraction of a particular phenotype is correlated with a particular gene.
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Replication of DNA: Before a cell undergoes nuclear division, either mitosis or meiosis, DNA is replicated during the S phase of the cell cycle. Replication doubles the amount of DNA, and each gene exists in at least two copies, one on each of the two chromatids, one of which goes to each daughter nucleus during anaphase.
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