ZOL 341 1st Edition Exam 1 Study Guide Lectures 1 10 Lecture 1 genes work by controlling the biochemical activities for growth and function of cells genome codes for morphological physiological and behavioral characteristics genetics molecular cellular organism population genetics the study of traits and the underlying basis of heredity and variation of those traits some characteristics are the result of several genes and environmental factors working together genetics influences every aspect of our lives disease susceptibility genetic disorders pharmaceuticals development intelligence personality Lecture 2 the molecular structure of DNA was key to understanding how DNA could carry genetic information how the molecule replicated Erwin Chargaf for most organisms adenine thymine guanine cytosine nucleotides are arranged as complementary base pairs A with T and C with G DNA nucleotides are composed of a deoxyribose 5 carbon sugar a phosphate group and one of four nitrogenous bases designated Adenine A Guanine G Thymine T Cytosine C complementary base pairing A T G C the 5 and 3 designations of the phosphate and hydroxyl at the ends of the DNA strands establish polarity the two strands are antiparallel micro RNAs active in regulation of gene expression in plants and animals reverse transcription uses an RNA template to produce complementary DNA transcription transcription uses one strand of DNA to direct synthesis of a single stranded RNA transcript template strand DNA strand from which the RNA is synthesized coding strand complementary partner of the template strand translation 3 translation converts mRNA into a sequence of amino acids 3 the resulting polypeptide upon folding makes up all or part of a protein 3 each amino acid is specified by a codon three consecutive nucleotides on the mRNA 3 the genetic code mRNA specifies an amino acid sequence using the genetic code 3 there are 64 possible triplet codons read in the 5 to 3 direction each specifies one amino acid 3 there are 20 common amino acids some amino acids are specified by one codon and others by up to six diferent codons synonymous evolution has a molecular basis life evolves as DNA acquires mutational changes the biochemical processes that replicate DNA and express genetic information are universal evolution the theory that all organisms are related by a common ancestry and have diversified over time natural selection is based on underlying genetic variation as one morphological form is favored over another the frequencies of alleles associated with each form are altered four processes that lead to changes in allele frequencies in a population over time mutation the slow addition of allelic variants that increase the diversity of a population natural selection the diferential reproductive success of members of a species migration the movement of members of a species from one population to another random genetic drift the random change of allele frequencies due to chance in rapidly mating populations Lecture 3 base stacking the ofsetting of adjacent base pairs so that their planes are parallel leads to the helical twist DNA replication bidirectional and semiconservative general mechanism of DNA replication is the same in all organisms some diferences have developed in the replication proteins and enzymes three models all shared the idea that the original strands of the duplex act as templates for daughter strand synthesis semiconservative conservative dispersive attributes of DNA replication shared by all organisms 1 each strand of the parental DNA molecule remains intact during replication 2 each parental strand serves as a template for formation of an antiparallel complementary daughter strand 3 completion of replication results in the formation of 2 identical daughter duplexes composed of one parental and one daughter strand requirements for DNA replication a template of single stranded DNA raw materials to be assembled into a new nucleotide strand enzymes and other proteins that read the template and assemble the substrates into a DNA molecule stages of replication initiation unwinding elongation termination consensus sequences the nucleotides found most often at each position of DNA in the conserved region Lecture 4 DNA proofreading has high fidelity due to instability of mismatched pairs configuration of the DNA polymerase active site proofreading function of DNA polymerase telomeres repetitive sequence at the end of linear chromosomes telomerase lengthens end of telomere prevents shortening of telomeres with multiple rounds of replication like the little piece of plastic on the end of a shoelace only in some cells telomere length is important for chromosome stability cell longevity and reproductive success telomerase is active in germ line cells and some stem cells in eukaryotes other cells have limited life spans 30 50 divisions polymerase chain reaction PCR an automated version of DNA replication that produces millions of copies of a short target DNA segment requires a double stranded DNA template containing the target sequence to be amplified a supply of the 4 DNA nucleotides heat stable DNA polymerase ie Taq polymerase 2 diferent single stranded DNA primers bufer solution steps of PCR 1 denaturation heat to 95 C 2 primer annealing reduce temperature to 45 68 C to allow primers to hybridize to their complementary sequences in the target DNA 3 primer extension raise temperature to 72 C to allow polymerase to synthesize DNA limitations of PCR some knowledge of the target DNA sequence is required in order to determine primer sequences amplification products longer than 10 to 15 kb are difficult to produce sanger sequencing dideoxynucleotide DNA sequencing dideoxy sequencing uses DNA polymerase to replicate new DNA from a single stranded template 4 standard deoxynucleotide bases are present in large amounts each of 4 reactions contains a small amount of one ddNTP Lecture 5 context of replication purpose is to accurately copy chromosomes in preparation for cell division happens in the nucleus happens during interphase will cover in later lecture RNA structure is similar to DNA but has uracil instead of thymine and ribose instead of deoxyribose has OH on 2 carbon instead of H is located in the cytoplasm and the nucleus mRNA produced by protein encoding genes is a short lived intermediary between DNA and protein and is the only type of RNA that undergoes translation transfer RNA tRNA bind an amino acid and deliver it