Bio Final Study Guide.docx

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Michigan State University
Biological Science
BS 181H

Bio Final Study GuideI MutationsMutations are beneficial becauseAllow for progeny to liveAllow for evolutionBeneficial harmfulCause genetic diseaseCancerMutationChange in the gene makeup of some inheritable trait a heritable change in the genetic materialPoint mutationsaffect only a single base pairChange base sequenceAdd or remove nucleotidesoChanges reading framethus changes amino acid sequence Silent mutationwhen the lace base pair of a reading frame is mutated coding for the same proteinBase substitutionstop codon Stops protein sequenceBase additionshifts frame MutationSickle cell anemia is the result of a single amino acid substitution resulting in fiberlike structures Common in Africacauses resistance to malaria So kind of goodA mutation n the intergenic region is noncoding so doesnt affect amino acidsdoesnt matter if mutatesMutations in each sitePromoterMutation would increase of decrease transcriptionTranscriptional response elementoperatorSame as promoterSplice junctionsCould change amino acid code and form a different polypeptide Translational response elementsDeleterious because affect proper translation into polypeptide and wouldnt be processed properlyEXPERIMENT Lederbergs Showed that mutations are random eventsReplica platedmade colonies on a petri dish and took a stamp of it and made a stamp on a bunch of other platesMutant cells would be lysed and killed on these platescolonies still grewGermlineSomatic cell mutationsGerm linePassed to offspring only Give rise to gametesSomatic cellseverything but germ line Location of mutation is therefore important to inheritabilitySpontaneous vs induced mutationsSpontaneous mutations result from abnormalities in biological processesoExposure to free radicalsoErrors in DNA replication point mutation caused by polymeraseoChanges in nucleotide products linkage between purines and deoxyribose can spontaneously breakoTransposonsSmall segments of DNA that can insert in various genomic sitesInduced oChemical agentscigarettes etcCalled mutagensphysical agents are tooSome chemicals substitute and dont perform as basesSome chemicals alkylate basesoPhysical agentsUV light and XraysCause deletions pyrimidine dimer formation crosslinking chromosomal breaks nicks in DNAoHigher mutation rate than physicalRadiationIonizing radiation oHas high energy and can penetrate deeply into biological materialsoX rays oGamma raysoBreaks in 1 or both DNA strands Nonionizing radiation oHas less energy and can only penetrate surface oSkin cells UV RadiationDimerscovalent bond between thymines that cause DNA to buckleRepair mechanisms can feel that buckle and take it out but its not always seenCan be replicatedWhy are children more sensitive Because theyre replicating fasterEXP AmesTested for rate at which second mutation occurstested mutagenicityUsed Salmonella that cannot synthesize histidineeither bacteria cannot grow unless histidine added to medium OR mutation occurs allowing for synthesis of histidineMixed salmonella rat liver extract and suspected mutagen and incubatedPlaced both on plates that lacked histidine and the mutagen plate was able to grow showing that a nutation allowed for histidine formationCant test carcinogenicity because that has to show that it causes cancerunethicalII DNA RepairCancerAll living organisms must have the ability to repair changes that occur in DNA in order to minimize mutationDirect repairWhen an enzyme removes a defective nucleotide and replaces it because alkylated etc Nucleotideexcision repairhave abnormal base a piece of DNA is removed Altered strand is removed and new segment is synthesizedMost commonFound in all eukaryotes and prokaryotesUndamaged strand is used as template for resynthesis of a normal complementary strandDirected by UvrAUvrB complex which tracks along DNA UvrC binds to UvrB and make a cut on both sides of the abnormality UvrD removes damaged region and releases DNA polymerase fills in the gap and DNA ligase seals the new strandNER and Human genetic diseaseoXP CS and PIBIDS inability to repair UV damage frequent in people with an inability to repair by NERMethyldirected mismatched repairDNA defect if a base pair mismatch not an abnormal nucleotideCancerdisease of multicellular organisms because calls proliferate out of controlIn 10 some cancers inheritable disposition to develop the diseaseMost cancers do not involve genetic changes from parent to offspringMostly due to exposure to carcinogenssmokingOrigins of the diseaseOriginate from a single cell that has one change in one or two cells that cause it to grow abnormallyTumorThe overgrowth of cells with no useful purpose Can be benign or cancerous or precancerousStagesoMalignantcell line that has lost ability to control cell division
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