BICD 100 Genetics.docx

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Biol/Genetics,Cellular & Develop
BICD 100
Keefe Reuther

Lecture 1 Tuesday July 02 2013 1146 PMDarwin oAll organisms from common ancestor o Differencesstructures of their genomeEvolution o A change in the genetic composition of a population over generationsEx 2 copies of every gene 1 male and 1 female These are two alleles versions of a geneGenetic composition allele frequency 51 blue allele 49 green allele Evolution happens when these numbers change o Evolution involves a population a group of potentially interacting reproducing individuals They need to be able to interactOrigin of Species Darwin o Evolution as a factPatternAccepted QuicklyEvidence of a common ancestor Mountain of evidence such as common bone structures o Natural Selection drives adaptationProcessRejected InitiallyNo mechanism for the creation of novel variationNo mechanism for inheritance of adaptationThomas MorganMutation o Worked w Drosophila o Previously thought mutations to be large causing speciation or new morphological features o Morgan quantified mutation its mechanism and its effect on bodyMechanism of Inheritance o Thought to be blending inheritance equal blend of both parents o Problem w blending inheritance any beneficial adaptation will be diluted and eventually disappear think of black dots on a screen exampleWeismann and Lamarckism o Lamarckism inheritance of acquired characteristics o Lamarckism disproved by infamous mouse tail clipping experiment o Debunked soft inheritance o Inherited characters are from genes of successful parentsGregor Mendel and Inheritance o Explained meiosis and inheritance one explains the otherModern Synthesis Evolution and Genetics o DNA Structure1944 Identified DNA as the material genes are made of Avery MacLeod based off of Griffith experiment1953 Determined structure of DNA WatsonCrickCandidates for genetic material DNA RNA Proteins polymers of 20 aa Griffith experiment with staph bacteria o Hershey Chase 1952 ExperimentBacteriophage experiment Radioactive sulfur and phosphorous o Nucleotide is composed of a sugar phosphate and base o Two types of bases Purines and PyrimidinesPurines 2 ring structures A and GPyrimidines 1 ring structure T C U o DNA has a sugar phosphate backbone phosphodiester bond o DNA is the most negatively charged in the body o Answer to slide B and E RNAStructure of DNA o Two findings became known as Chargaffs rules Erwin ChargaffBase composition of DNA varies btw SpeciesIn any species theof A and T bases are equal and CG are also equal o Building a Structural Model of DNAAfter DNA was accepted as genetic material needed to figure out structureUsed Xray CrystallographyKnew width of DNA so in order to for it to be uniform purine and pyrimidine must bond to form 3 ring structures Cant have 3 ring then 2 ring etc Limits optionsAlso knew it was some type of spiral ladder arrangement from diffraction patternHas minor and major grooves o Why cant A pair with G and T pair with CPairing is always between Pyrimidine and Purines always an equal 3 rings acrossNature of the bonds AT have 2 hydrogen bonds and CG have 3 hydrogen bondsN and O tend to have negative charges while C and H tend to have positive charges o These are SMALL charges but causes H bondsMyostatin o Gene that inhibits muscle growth o 2 base pair deletion in myostatin gene causes a buff dog this gene also found in humans and miceMutations o The ultimate source of genetic variation o Point mutation Change in single nucleotide can have sig impact on traitTypically in DNA replication can lead to production of an altered proteinSilent Nonsense and MissenseSwitching out awith aconservative will have a less effect than switching awith anonconservative Least Silent Neutral Con Missense Non Con Missense Mostly negative sometimes positive Most Nonsense Negative effect SugarBase P SugarBase P Sugar BaseLecture 2 Tuesday July 09 2013 1124 AMWhat DNA Mutates o Some DNA mutates more often than other DNA o Some mutations are acted on more heavily by natural selection o DNA that doesnt do anything is more likely to mutate quickly than a gene that is necessary for your own survival o If you want to do a phylogeny you should look at DNA that have changed If you want to do something like a paternity test you need DNA that doesnt really change o A large fraction of genome does not produce genes w products w known function o Coding DNA is only about 11 of genomeSimplesequence DNA repetitious DNA 6 of human genome o Satellite DNA 14500 bp repeats in tandem 20100kb telomeres and centromeres o Microsatellites 113bp repeats in tandem up to 150bpEvolves relatively quickly not coding for anything easily mutated o Often function in keeping things together protecting chromosomes o Simple sequence repeats may occur through replication errorsBackward slippageOne of repeats popped out to the sideWill result in daughter DNA w an extra repeat o Number of repeats can change through unequal crossing over during meiosisCrossing over must be equal ensured bc sequences matchBut in repeated sequences all the sequence matches so they may cause unequal crossing overThis can change the number of crossing over during meiosis of repeats can be highly variable between individualsDiseases associated w repeat expansions o Huntingtons Disease o Fragile XCGG repeats over 200 times results in the gene turning offInterspersed repeats mobile DNA elements o Mobile DNA elementsTransposable elements o DNA can move within and between chromosomes o Developed the transposon theory by studying corn kernel coloration Barbara McClintock o Purple white and speckled Purple is the wild type C is responsible for purple in white mutants the Ds moved and inserted itself into C In speckled the Ds moves back out of C
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