MBG 2040 Lecture Notes - Lecture 1: Dihybrid Cross, Drug Design, Zygosity
2 May 2018
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Introduction & Review
Why study genetics?
• Genetics plays a critical role in understanding disease
• Genetics improves agricultural practices
• Genetics in drug design, development & production
Principles of Medelian Genetics
Chapter 3
Outline:
• Define, recognize and apply Mendel's first principle
• Distinguish genotype and phenotype
• Solve genetic problem relating to monohybrid crosses
• Interpret pedigrees
o Assess mode of inheritance
o Assign genotypes
• Use the rules of probability to determine genotypic and phenotypic proportions
Fundamental Genetic Concepts:
• Genes are inherited independently of each other
• We apply the principles of medelian genetics to calculate the probability and track the
distribution of heritable traits in individuals and populations
• Gene - fundamental unit of heredity
o Come in multiple forms = alleles
• Genotype confers phenotype
• Genes are located on chromosomes
• Genetic information is transferred from DNA to RNA to protein
Terminology:
• Gene - genetic factor that determines a trait
• Allele - one of two or more alternative forms of a gene
• Locus - specific place on a chromosome
• Genotype - set of alleles possessed by an individual organism
• Hetero
• zygote - an individual organism possessing two different alleles at a locus
• Homozygote - an individual possessing two of the same alleles at a locus
• Phenotype - appearance or manifestation of a character
• Character/Characteristic - an attribute or feature
Basic Principles of Heredity:
• Mendel discovered basic principles of heredity
• Monohybrid cross:
o Each parental homozygote produces one kind of gamete
o The F1 heterozygotes produce two kinds of gametes in equal proportion
o Self-fertilization of the F1 heterozygotes yields tall and dwarf offspring in a 3:1 ratio
• Dihybrid cross:
o A study of two traits (G and W)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Why study genetics: genetics plays a critical role in understanding disease, genetics improves agricultural practices, genetics in drug design, development & production. Outline: define, recognize and apply mendel"s first principle, distinguish genotype and phenotype, solve genetic problem relating to monohybrid crosses. Interpret pedigrees: assess mode of inheritance, assign genotypes, use the rules of probability to determine genotypic and phenotypic proportions. Take home problem 1: an albino child can be born only if the two parents are heterozygous carriers of recessive allele, probability for the other parent to be heterozygous is 2/3 aa and 1/3 aa. If both parents are heterozygous, the probability of an albino child is 1/6: 1 aa (father) * 2/3 aa (mother) * 1/4 aa (child) Take home problem 2: you have a plant with a wild-type phenotype, but genotype is unknown, describe an experiment that will determine the genotype (aa, aa, or aa)
