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IN: Message ActivityGenetic MutationsHuman GeneticsI. Mutations – permanentchanges to the nucleotide basesequence of DNA;Chromosomes have extra ormissing genetic materialAnimal mutationsII. Results of DNA ChangesA. Increased geneticvariation of offspringIII. Two Categories of MutationsB. Harmful - Cause cancerC. Helpful – Createantibiotic resistantbacteria (bad for usgood for bacteria)D. Neutral – manyoccur on introns(non-coding segmentof DNA) so they arenot expressed asproteinsA. Germline Mutationsa.b.c.d.Occur during meiosisAffect sex cellsPassed from parent to offspringToo many or not enough chromosomesEx. Down SyndromeAntibiotic Discs1
B. Somatic MutationsIV. Where in the DNA do mutations occur?a. Take place in body cellsb. Not passed to offspringc. Localized to a single or small group of cellsA. Gene Mutations - occur within thesequence of one gene.Ex. Skin cancer from UV radiation exposureB. Chromosome Mutations – occur whenchromosome structure changesV. Gene Mutations (2 types)A. Point Mutations – substitutions occur in asingle base paira. Silent Mutation –base pair substitution doesSilentnot change amino acid sequenceEx: CUU ( Leucine ) to CUC ( Leucine )b. Missense Mutation –base pair substitutionchanges amino acids sequenceEx: AGU (Serine) to AGA (Arginine)c. Nonsense Mutation –base pair substitutionchanges to a stop codonEx: AGA (Arginine) to UGA (Stop)Normal HbSicklecell HbOne base pairsubstitution causeshemoglobin to have thewrong shape.Sickle-cell Diseaseis caused by amissense mutation.Diseases Caused byPoint Mutations Cystic fibrosis Cancer Neurofibromatosis (tumors formon the nerves anywhere in thebody) Progeria (early aging)time.2
B. Frameshift Mutations1. A single base pair in theDNA is deleted oradded.2. Every codon after thedeleted or added basewould be different.3. Alters the readingframe of mRNAtriplets4. Makes the DNAmeaningless andresults in a short,nonfunctional proteinFrameshiftDiseasesvideoSyndrome with facialdeformity, skeletalanomalies, and mentalretardationVI. Chromosome MutationsStop Day 1Do Karyotype LabA. Deletion: removal of achromosomal segmentB. Duplication: repeats achromosomal segmentC. Inversion: segment reversal in achromosomeD. Translocation: movement of achromosomal segment toanother non-homologouschromosome3
Name theMutationVII. Causes of MutationsA. Spontaneous (chance):1. Base pairing error during DNA replication THE DOG BIT THE CAT.THE DOB ITT HEC AT.Deletion withFrameshiftTHE DOG BIT THE CAT.THE DOG BIT THE CAR.Point2. Errors during meiosis The fat cat ate the wee rat.The fat tar eew eht eta tac.InversionB. Mutagen - environmental factor thatdamages DNAEx: UV sunlight (cancer), cigarette tar, asbestos,X-ray, radioactive isotopes, etc.VIII. Irregular Chromosome NumberA. Caused by Nondisjunctiona. Failure of chromosomes to separatecorrectly during of meiosisb. Result is extra or missing chromosomesWhat are these two pictures called?KARYOTYPE Shows chromosomes paired bysize, shape, and appearance in metaphase.Amniocentesis4
IX. Nondisjunction Diseases/SyndromesA. Monosomy (one missing chromosome)a. Nearly all monosomies are fatalb. Examples:1. Turner syndrome (XO female) - 45B. Trisomy One extra single chromosome ispresenta. Many, but not all, are fatalb. Examples: (47 instead of 46)1.chromosomes instead of 462. Jacob syndrome XYY males3. Triple X Syndrome XXX females4. Down Syndrome extra 21stchromosomechromosome 5Klinefelter SyndromeLow TestosteroneInfertilityIncomplete MasculinizationFemale Body Hair DistributionDecreased LibidoLow EnergyDevelopmental DelaysLearning DisabilitiesNormal or High IQSocial Interaction DifficultiesADHDImpulse Control DisorderDepressionLow Self EsteemTriple X syndrome(trisomy X or 47,XXX) Characterized by anadditional X chromosome Most females with tripleX syndrome have normalsexual development andare able to conceivechildrenKlinefelter’s Syndrome XXY male(rare cases (48,XXXY) or (49,XXXXY)2. Cri du chat partial deletion ofJacob’s Syndrome XYYMost boys who have theextra Y chromosome willgo through life withouthaving been diagnosed.Male inherits an extra Xchromosome. This meansthey have two Xchromosomes and one Y(written 47,XXY).Individuals with Klinefeltersyndrome are malebecause they have at leastone copy of the Ychromosome.Occurs inonly 1 outof every1,000birthsAbout 1 in 500 to 1 in 1000males is born with XXYchromosomes. It is the mostcommon chromosome changein men with very low orabsent sperm counts.Extra Y chromosome is ininherited from the fatherDown Syndrome Trisomy 21Triple X Physical signs: Tall stature Small head Vertical skin folds ininner corners of the eyes Delayed development ofmotor skills, speech andlanguage Learning disabilities,such as dyslexia Weak muscle toneThis condition occurs in about 1 in 1,000 newborn girls. Five to 10 girls with tripleX syndrome are born in the United States each day. Decreased muscle toneExcess skin at the nape of neckFlattened noseSeparated joints between the bones ofthe skullSingle crease in the palm of the handSmall ears and mouthUpward slanting eyesWide, short hands with short fingers Impulsive behaviorPoor judgmentShort attention spanSlow learning5
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ADHD Impulse Control Disorder Depression Low Self Esteem Jacob’s Syndrome XYY Most boys who have the extra Y chromosome will go through life without having been diagnosed. Occurs in only 1 out of every 1,000 births Extra Y chromosome is in inherited from the father Triple X syn
