BIO Notes - 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

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

Example: a gene that affects shape of hemoglobin – sickle cell anemia (gene is for hemoglobin but affects shape of cell) Continuous Variation : many genes & environment result in a gradient of a character Sex Chromosomes Karyotyping : distinguishing among the different chromosomes – autosomes vs. sex chromosomes Two types of sex chromosomes: X & Y  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.