ANTH 1001H General Anthropology - Genes Notes PDF

Genetics Study of how living organisms grow, store, and repair genetic instructions ❖ Natural Selection = Differential survival and reproduction of individuals due to differences in phenotype Direction of Natural Selection: Variability among species; selection based...

Genetics Study of how living organisms grow, store, and repair genetic instructions ❖ Natural Selection = Differential survival and reproduction of individuals due to differences in phenotype Direction of Natural Selection: Variability among species; selection based on environmental conditions Mutations = Random changes in genetic material Genetic Drift = Random changes in allele frequency in a population Gene Flow = Movement of alleles between populations ❖ Transmission of Genetic Information Occurs through meiosis (sex cell division), where sperm and eggs carry half of the parent’s genes Genetic material undergoes shuffling and recombination, leading to variability Not all genetic information is passed on; some may be lost or mutated ❖ Genotype vs. Phenotype Genotype = The genetic makeup of an individual Phenotype = The observable characteristics resulting from a genotype and environmental interactions ❖ Evolution = Descent + Modification Humans are products of evolution, which is ongoing and influenced by environmental changes Genetic Stability = Can also be considered a form of evolution Historical Context ❖ Gregor Mendel (1865): Pioneered the study of genetics through pea breeding, established the concept of particulate inheritance Alleles = Alternate forms of a gene affecting phenotype Genes = Sections of DNA coding for proteins; organized into chromosomes Chromosomes = Humans have 23 pairs containing multiple genes Locus = The specific location of a gene on a chromosome ❖ Genetic Terminology Heterozygous vs. Homozygous Heterozygous = Different alleles Homozygous = Identical alleles Dominant vs. Recessive Dominant = Always expressed phenotypically Recessive = Requires two copies to appear in phenotype  Punnett Square = A tool for predicting genetic variation in offspring Codominance = Both allele are expressed Linkage = Genes that are inherited together because they are on the same chromosome Polygenic Traits = Traits controlled by multiple genes (potential height or/and growth rate) Pleiotropic Traits = One gene affects multiple traits (e.g., sickle cell anemia) Natural Selection ❖ Charles Darwin: Developed the theory of natural selection based on observations of variation and adaptation in species Relative reproductive success of variants Natural selection acts on phenotypes, not directly on genes Adaptation occurs over long periods; evolution is multi-directional ❖ Population = An interbreeding group capable of producing offspring ❖ Gene Pool = All allele variants in a population, influencing genetic diversity ❖ Types of Natural Selection Stabilizing Selection = Favors common traits, maintains existing adaptations Directional Selection = Favors uncommon traits, leading to changes in population; eg., peppered moth Diversifying Selection = Favors extreme traits, adapts to varying environmental conditions Speciation The process by which new species arise ❖ Anagenesis = Gradual evolution of a single species ❖ Cladogenesis = Branching evolution resulting in multiple species ❖ Isolating mechanisms prevent gene flow (eg., geographical, behavioral) ❖ Paleospecies = Inferred from fossil evidence ❖ Biological Species = Defined by reproductive isolation