The classical views of the concept of gene

The classical views of the concept of gene -...

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The classical views of the  concept of gene  
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Gene is the unit of transmission  The Mendel s First Law : Alleles segregate each generation  The monohybrid crosses (simple crosses involving only one pair of contrasting traits)  performed by Mendel (1868)-the garden pea cross experiments  P1: Tall x Dwarf F1: All Tall F1 x F1: Tall x Tall F2: 3/4 Tall 1/4 Dwarf Where P1: parental generation F1: first filial generation F2: second filial generation
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Phenotypes of Pea Plants 2-4 Figure 2.4
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Character Phenotypes F1 F2 F2 Dominant Results Ratio Stem Tall/dwarf Tall 787 tall 2.84:1 277 dwarf Pods Axial/Terminal Axial 651 Axial 3.14:1 207 terminal Full/constricted Full 882 full 2.95:1 299 constricted Yellow/green Yellow 428 yellow 2.82:1 152 green Seeds Round/wrinkled Round 5474 round 2.96:1 1850 wrinkled Yellow/green Yellow 6022 yellow 3.01:1 2001 green Flowers Violet/white Violet 705 violet 3.15:1 224 white
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 To explain these results, Mendel proposed the    existence of particular  unit factors unit factors  for each trait.  He suggested that these factors serve as  the  the  basic units of heredity and are passed  basic units of heredity and are passed  unchanged from generation to generation unchanged from generation to generation determining various traits expressed by each  individual plant.
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Mendel s first three  postulates  1.  Unit factors in pairs:  Genetic characters are controlled by unit  factors that exist in pairs in individual organisms. 2.  Dominance/recessiveness:  When two unlike unit factors  responsible for a single character are present in a single individual,  one unit factor is dominant to the other, which is said to be  recessive.         Complete dominance  vs  incomplete dominance  vs   codominance 3.  Segregation:  During the formation of gametes, the paired unit  factors separate or segregate randomly so that each gamete  receives one or the other. All unit factors represent units of inheritance (transmission) are  called genes.
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Complete dominance  vs  incomplete dominance  vs   codominance
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Genetic control of the human ABO blood type Genotype Antigens present on red blood cells ABO blood group phenotype Antibodies present in blood fluid Blood types that can be tolerated in transfusion Blood types that can accept blood for transfusion IAIA A Type A Anti-B IAIO A Type A Anti-B IBIB B Type B Anti-A IBIO B Type B Anti-A IAIB Type AB Neither Anti-A or Anti-B AB only IOIO Neither A nor B Type O Anti-A & Anti-B O only A, B, O & AB
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The classical views of the concept of gene -...

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