Genetics: Introductory Notes

Principal Points: Genetics can be divided into 4 subdisciplines – Transmission genetics – passage of genes from generation to generation – Molecular genetics – structure and function of genes at the molecular level – Population genetics – heredity in groups of individuals where the traits are determined by one or a few genes – Quantitative genetics – heredity of traits in groups where the traits are determined by many genes simultaneously

Refresher… Eukaryotes – genetic material is located in a membrane-bound nucleus inside the cell – It is distributed among several chromosomes Prokaryotes – lack a membrane-bound nucleus Genetics – science of heredity – Heredity – Molecular nature of genetic material – Ways genes control life functions – Distribution and behavior of genes in populations

Principal Points: Genetics – science of heredity – Heredity – Molecular nature of genetic material – Ways genes control life functions – Distribution and behavior of genes in populations Gene activity underlies all life processes (from cell structure to cell function to reproduction) Helpful website:

CLASSICAL & MODERN GENETICS Genetic research was revolutionized in: – 1972 when Berg constructed the first recombinant DNA molecule in vitro rDNA – combining of 2 pieces of DNA – 1973 when Boyer & Cohen cloned a recombinant DNA molecule for the first time – 1986 when Mullis developed a PCR (polymerase chain reaction) to amplify specific segments of DNA (this spawned a second revolution)

BASIC CONCEPTS OF GENETICS DNA – genetic material of all living organisms (eukaryotes & prokaryotes) RNA – genetic material Genome – full DNA sequence of an organism; Nucleotides – building blocks of DNA (sugar, phosphate group, N-containing base) – 4 bases – A, G, C, T – RNA – U replaces T – Sequence of bases determines genetic information

Purine Pyrimidines AdenineGuanineCytosineThymine

BASIC CONCEPTS OF GENETICS Gene – specific sequence of nucleotides that codes for a specific Chromosomes– structure of the genetic material – Eukaryotes– linear structure of DNA & protein, # varies among species – Prokaryotes– single, usually circular structure Traits are determined by inherited genes, and each organism contains 2 copies of each gene

BASIC CONCEPTS OF GENETICS – Alternative versions of genes are called alleles – Individual with identical alleles for a trait is homozygous – Individual with 2 different alleles for a trait is heterozygous – Complete genetic makeup of an organism is the genotype – The observable properties is the phenotype Phenotype is due to genotype and how it interacts with the environment

BASIC CONCEPTS OF GENETICS Dominant - the allele that most often shows up in a natural population – Can show up as homozygous or heterozygous genotypes Recessive - the allele that least often shows up in a natural population – Shows up only as the homozygous genotype