9 1 16 MOLECULAR GENETICS The answer to Darwin s First unanswered question o Genetic mutation is the ultimate source of new biological variation o Knowledge about mutations caused some to reject natural selection as a mechanism of change o In the 1930s genetics and Darwinian theory was wedded in what was 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 proteins o 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 DNA o 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 DNA o A double helix made up of sequences of bases sugars and phosphates o 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 stairs o The basic unit of DNA is called a nucleotide REPLICATING DNA o When new cells form DNA is first replicated o Hydrogen bonds holding bases together release o Unattached nucleotides are attracted to complementary nucleotides forming new strand o Replication complete cell division follows PROTEIN SYNTHESIS o DNA unzips o Codes in sets of 3 and 4 GENE DEFINED o A unit of dna that produces a functional chain of protein o There are 3 billion base pairs in dna MUTATION DEFINED o An alteration in the base sequence of genes o Ultimate source of genetic variation o Mutations caused by radiation and other common stimuli o 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 cells GENETICS AND EVOLUTION Gregor Mednel o Celibate monk to teach us about sex o For years Mendel conducted experiments with garden peas to determine the rules of inheritance o HE hoped that by crossing pure strains of pea plants he could find patterning in the percentages of plant traits seen in hybrid generations 2 o Genetic material is neither blended nor destroyed material from each parent is retained to its individuality o Mendel tested 7 traits o He reasoned that rtraits must be controlled by discrete particles and that each plant had two particles for each trait one inherited from each parents o Law of Segregation o Look at meiosis and mitosis slides from bio o The particles that get passed down as genetic information are known as chromosomes o Members of each pair are known as homologous pairs because they are alike in size and structure and they carry information influencing the same trait o Law of Independent assortment o Complicating matters linkage crossing over sex linked genes polygenesis epigenetic o EVOLUTION can now be defined as changes in the gene frequencies in population over time o Genetic drif o Gene flow o Natural selection WHY STUDY PRIMATES Our closest living relatives Comparative anatomy o Allows inferences about the behaviors of our ancestors o Provides basis for reconstructing evolutionary relationships phylogeny Observations of living primates General Trends in Primate Evolution o Mammalian Advantages Homeothermy Large complex brain 3 Live birth location and prolonged mother infant bond Heterodontic dentition 4