Genetics 2153 Review Main Points (aced the test and got 96%)

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Louisiana State University
Biological Sciences
BIOL 2153

Genetics 2153 Review Main PointsChapter 1Chromosome packingoDNA wrapped around histone nucleosomeoBunch of nucleosomes together chromatinoChromatin form loops and pack super tightly together forming the chromosomeDouble helix Nucleosomes Chromatin solenoid structureTightly condensed Chromatin ChromosomePairs 122 in a human karyotype are the autosomes pair 23 is the sex chromosomeoChromosomes same length XX femaleoChromosome different length XY maleCentral dogma of molecular biologyoFrancis CrickoDescribes flow of hereditary infooLead to changes in allele frequencies in a population over timeoNatural selection best adapted characteristic increase in a populationoMigration movement of members between populations alter allele frequenciesChanges because different populationsoMutation addition of allelic variants increasing diversity of population serve as raw material of evolutionary change oRandom genetic drift the random change of allele frequencies due to chance in rapidly mating populationsChanges because one population mates a lot ProbabilityoPredicting outcome diseased child problemsoPredicting phenotypegenotypeChapter 2Test cross Unknown genotype with pure breeding oR x rrRR x rr 100 heterozygous all dominant phenotypeRr x rr 50 heterozygous 50 homozygous recessive11 ratio of dominant to recessive phenotypeBoth pure breeding crossoGG x ggF1 all heterozygousF2selffertilize hetro 121 genotype 31 phenotypeFraming a hypothesisoNull observed values not different from expected chance aloneoAlternative observed values are different from expectedChiSquare 25oallows for scientist to objectively determine whether results are consistent with expectations or noto large samples outcomes predicted by chance have a normal Gaussian distribution AKA bellshaped curveoOutcomes are distributed around the mean average outcome and the probability of an experimental outcome gets smaller the further it is from the mean oProbability of particular outcomes is quantified by a measurement called standard deviationNorm distribution682 fall within 1 of mean954 fall within 2 of meanAn experimental outcome that is more than 2 from the mean shows a statistically significant difference between the observed and expected outcomeoChisquare Test Analysis 22OEEO observed valuesE expected valuesProbability P value is how the test is interpretedP value is the probability that the results of another experiment of the same size and structure will deviate as much or more from the expected results by chance2 Low values associate with high P values which indicate chance alone likely explain deviationsP value is dependent on degrees of freedom dfof classes1P value055 hypothesis of chancenull rejectedto the right on the chisquare chartP value055 shows significant deviation between observed and expected results hypothesis of chanceto theon the chisquare chartacceptedleftP value0522 critical value critical valueAccept Null Reject Null HypothesisHypothesisData deviations are Data deviations
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