BIO Notes - BIO Notes Inheritance Blending does not exist...

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BIO Notes Inheritance Blending – does not exist (black + white gray) isn’t true Gregory Model Alleles – different forms of a gene (the ones you get from mom/dad) EX: S = round; s = wrinkled Capitilization indicated dominancy; S is dominant, s is recessive With 2 genes: you have possibilites SS = dominant homozygous (round), Ss – heterozygous (round) Ss = recessive homozygous (wrinkled) Punnet Square S s S SS Ss s Ss Ss Phenotype – what you see (a gene being expressed) Genotype – the genes you have (whether expressed or not) Incomplete Dominance – heterzygote form blends character together (not really blending) Segregation – in gamete formation, the 2 genes of a parent separate in Meiosis 1 so that each daughter cell (gamete) receives only one of the genes, Generations – parent (P), first filial (F1), second filial (F2) Phenotypes vs. Genotypes How to determine if homozygous dominant (EE) vs. heterzygous (Ee) To do this, cross with recessive homozygous (ee) - If it is homozygous (dominant (EE)), all genotpes will be - If it is heterozygous (Ee), half of the genotpyes will be recessive Independent Assortment – 2 different traits on different non-homologous chromosomes will segregate without regard to each other. (SsYy) - Phenotypic ratios if heterozygous for both traits Parental Generation (P) F1 Generation F2 Generation
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Sperms Eggs SY Sy sY sy SY SSYY SSYy SsYY SsYy Sy SSYy SSyy SsYy Ssyy sY SsYY SsYy ssYY ssYy sy SsYy SSyy SsYy ssyy 9 are round yellow 3 are wrinkle yellow 3 are round green 1 is wrinkled green Incomplete Dominance : blending of different forms of alleles Differs from old idea of blending Co Dominance – both alleles exposed in heterozygote EX type AB blood cells - There is Type A, B, O and AB (which isn’t A or B) Multiple Alleles (more than 2 forms of a gene) Blood Type Genotype Antibodies Made A [A]A or [A]O Anti B B [B]B or [B]O Anti A AB [A]B Neither anti A nor Anti B O [O]O Both Anti A and Anti B Epitasis : One gene masks expression of any other genes affecting a trait Example: Hair color has a lot of genes that affect it, sometimes there is a gene that masks all other genes which is called epitasis In Labrador retrievers, the black gene is the epitasis (covers yellow genes). There are several genes for one characteristic; an epitasis will mask all others Pleiotropy – expression of an allele can affect expression of an unrelated phenotype
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Example: a gene that affects shape of hemoglobin – sickle cell anemia (gene is for hemoglobin but affects shape of cell) Continuous Variation Sex Chromosomes Karyotyping : distinguishing among the different chromosomes – autosomes vs. sex chromosomes These determine the sex of an individual Females have XX (homozygous) males have XY (heterozygous) In mammals, male determines sex of offspring (in birds, females determine sex of offspring) Because Y chromosome is much shorter than X, for some genes there is no counterpart on the Y. This is called a sex-linked characteristic because there is no counterpart on Y which allows an
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BIO Notes - BIO Notes Inheritance Blending does not exist...

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