Made by Tae Ha, MD; 01/14/2020 HEREDITY INTRO/GENETICS Terminology -MOLECULAR GENETICS Focuses on GENES as functional units of HEREDITY, or how we inherit specific traits from our parents. -CLASSICAL GENETICS Branch of Genetics that focus solely on the VISIBLE ELEMENTS resulting from the inheritance of genes. -DNA>GENES (ALLELES)>CHROMOSOME>CHROMOSOMAL (HOMOLOGOUS) PAIRS (X23; 22 AUTOSOMAL, 1 SEX)->GENOME -GENES encodes for a specific trait, and located at a specific LOCUS. -ALLELES (each individual has 2 per gene) are the diﬀerent variations in a specific gene; DOMINANT vs RECESSIVE traits; Complicated by INCOMPLETE (“blending” of traits; i.e. red vs white vs pink eye colors) and/or CO-DOMINANCE (both traits fully expressed; i.e. blood types: A and B are co-dominant whereas O is recessive) -Both AO and AA genotypes encode for the same blood type A, which would be the phenotype; O blood type needs 2 recessive O alleles -HOMOZYGOUS vs HETEROZYGOUS in GENOTYPE (vs PHENOTYPE—>the actual physical manifestation; many diﬀerent genotypes can result in the same phenotype depending on the concept of DOMINANCE -Law of Independent Assortment: States that the alleles of one type of gene separates independently of an allele of a diﬀerent gene. In other words, genes must not be “linked” -Law of Segregation: States that two alleles of a single gene/trait will separate randomly. In other words, there is a 50/50 chance of getting the mom’s vs dad’s copy. ***Both obviously occurs during Meiosis, the production of gametes (sperm, egg) -Punnett Squares: Used to calculate probabilities, or the likelihood, of producing certain genotypes (and therefore, also phenotypes) in oﬀsprings if you know the genotypes of the parents. Can also be worked backwards. -Monohybrid vs Dihybrid Crosses: In dihybrids, both parents are hydrids at both genes (of interest) -Independent Assortment: Assumes the genes of interest are not “linked”; they are on diﬀerent chromosomes. What if they are “linked”? (especially in “sex-linked”) -Dominance vs Incomplete Dominance vs Co-Dominance: Results in diﬀerent phenotypes -Multiple alleles Mendelian Vs Non-Mendelian Genetics Everything we discussed above (EXCEPT INCOMPLETE DOMINANCE AND CO-DOMINANCE which describes Non-Mendelian Genetics) is Mendelian.