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Mendelian Genetics K. Sathasivan Basic genetic terms. Mendel's laws of inheritance. Complexities of genetic expression. Mendelian genetics in Humans
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Basic Terms
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Figure 14.0 Painting of Mendel
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Figure 14.0x Mendel
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Figure 14.x1 Sweet pea flowers
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Law of Segregation Allele pairs segregate (separate) during gamete formation and the paired condition is restored by the random fusion of gametes at fertilization.
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Figure 14.1 A genetic cross
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Figure 14.2 Mendel tracked heritable characters for three generations
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Table 14.1 The Results of Mendel’s F 1 Crosses for Seven Characters in Pea Plants
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Figure 14.x2 Round and wrinkled peas
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Figure 14.4 Mendel’s law of segregation (Layer 1)
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Figure 14.4 Mendel’s law of segregation (Layer 2)
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Figure 14.5 Genotype versus phenotype
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Figure 14.6 A testcross
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Law of Independent Assortment Law: The segregation of each allele pair is independent of other allele pairs. The individual allele pairs need to be located on separate loci, far from each other to allow independent assortment during gamete formation.
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Figure 14.3 Alleles, alternative versions of a gene
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Figure 14.7 Testing two hypotheses for segregation in a dihybrid cross
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Figure 14.8 Segregation of alleles and fertilization as chance events
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Complexities of Gene Expression Incomplete Dominance Co-dominance Epistasis Polygenic characters Pleiotropy Environmental effect Developmental effect
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Figure 14.9 Incomplete dominance in snapdragon color
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Figure 14.9x Incomplete dominance in carnations
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Figure 14.10 Multiple alleles for the ABO blood groups
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Figure 14.10x ABO blood types
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Figure 14.11 An example of epistasis
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Figure 14.12 A simplified model for polygenic inheritance of skin color
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Figure 14.13 The effect of environment of phenotype
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Figure 14.15 Pleiotropic effects of the sickle-cell allele in a homozygote
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Mendelian Inheritance in Humans Recessive Traits Albinism, Cystic Fibrosis, Tay Sachs, Sickle Cell, PKU, Galactosemia Dominant Traits Achondroplasia Alzheimer’s, Huntington, Hypercholesterolemia
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Polygenic Traits Heart Disease Cancer Diabetes Alcoholism Schizophrenia Manic Depression
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Figure 14.14 Pedigree analysis Dominant Traits Widow’s Peak, Freckles and Free Ear Lobe
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Figure 14.16 Large families provide excellent case studies of human genetics
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Early Detection of Human Genetic Disorders Amniocentesis Chorianic Villus Sampling (CVS) Ultrasound Fetoscopy Screening of embryos
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Figure 14.17 Testing a fetus for genetic disorders
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Summary Basic genetic terms. Genotype, phenotype, gene, allele, dominant, recessive, homozygous and heterozygous etc. Mendel's laws of inheritance. Law of segregation and law of independent assortment. Complexities of genetic expression. Incomplete dominance, codominance, epistasis, pleiotropy etc. Mendelian genetics in Humans Dominant and recessive disorders and early detection techniques
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