9/1/16MOLECULAR GENETICS9/1/16MOLECULAR GENETICS- The answer to Darwin’s First unanswered questiono Genetic mutation is the ultimate source of new biological variationo Knowledge about mutations caused some to reject natural selection as a mechanism of changeo In the 1930s genetics and Darwinian theory was wedded in whatwas called the “New Synthesis” Both are relevant: natural selection operates on variations created by mutation (and other sources)o Genetics provides the blueprint for the reproduction, growth, and development of organisms. IT does this by giving info on functions of proteinso Cells are the basic structural, functional, and biological units of all known living organisms A cell is the smallest unit of life that can replicate independently Each cell contains a nucleus that contains DNA- FUNCTIONS OF DNAo Transmits info from generation to generation of cells (growth and replacement)o Transmits information from generation to generation of cells (reproduction)o Instructs cells about which proteins to make and when to make them (hence it tells cells what to be and how to function)- STRUCTURE OF DNAo A double helix made up of sequences of bases, sugars, and phosphateso When unwound, the helix resembles a ladder, with the bases bonded in a set fashion (a/t, c/g) like rungs and sugar and phosphates as stairso The basic unit of DNA is called a nucleotide- REPLICATING DNAo When new cells form, DNA is first replicatedo Hydrogen bonds holding bases together releaseo Unattached nucleotides are attracted to complementary nucleotides, forming new strando Replication complete, cell division follows- PROTEIN SYNTHESISo DNA unzipso Codes in sets of 3 and 4- GENE DEFINEDo A unit of dna that produces a functional chain of proteino There are 3 billion base pairs in dna- MUTATION DEFINEDo An alteration in the base sequence of geneso Ultimate source of genetic variationo Mutations caused by radiation and other common stimulio We experience many mutations but few have meaningful effects Redundancy in codons ensures normal protein synthesis despite mutations Only mutations that matter are those in sex cellsGENETICS AND EVOLUTION- Gregor Mednelo Celibate monk to teach us about sexo For years, Mendel conducted experiments with garden peas to determine the rules of inheritanceo HE hoped that by crossing pure strains of pea plants he could find patterning in the percentages of plant traits seen in hybrid generations2o Genetic material is neither blended nor destroyed, material fromeach parent is retained to its individualityo Mendel tested 7 traitso He reasoned that rtraits must be controlled by discrete particles, and that each plant had two particles for each trait, one inherited from each parentso Law of Segregationo Look at meiosis and mitosis slides from bioo The particles that get passed down as genetic information are known as chromosomeso Members of each pair are known as homologous pairs because they are alike in size and structure and they carry information influencing the same traito Law of Independent assortmento Complicating matters: linkage, crossing over, sex-linked genes, polygenesis, epigenetico EVOLUTION can now be defined as changes in the gene frequencies in population over timeo Genetic drifo Gene flowo Natural selectionWHY STUDY PRIMATES- Our closest living relatives- Comparative anatomyo Allows inferences about the behaviors of our ancestorso Provides basis for reconstructing evolutionary relationships(phylogeny)- Observations of living primates- General Trends in Primate Evolutiono Mammalian Advantages Homeothermy Large, complex brain3 Live birth, location, and prolonged mother-infant bond Heterodontic