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Studying Human Inheritance 12-1 & 12-2
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Pea Characteristics http://mac122.icu.ac.jp/BIOBK/BioBookgenintro.html
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GENES are more complicated than MENDEL thought Some traits have more than two allele choices = ____________________ traits EX: A,B,O blood type glycoproteins MULTIPLE ALLELE
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GENES are more complicated than MENDEL thought Some traits are determined by more than one gene =_____________traits EX: Human height, Intelligence http://www.bcps.org/offices/lis/models/life/images/grow.JPG POLYGENIC
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GENES are more complicated than MENDEL thought POLYGENIC traits have lots of “in-between” phenotypes http://www.newtonswindow.com/problem-solving.htm There aren’t just SMART people and DUMB people…. there is a whole range of intelligences in-between
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GENES are more complicated than MENDEL thought Some genes are LINKED TO other genes _____________ traits are linked to a sex chromosome SEX-LINKED
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SEX DETERMINATION XX = Xy = female male Images from: http://members.tripod.com/~yenial/chromosome.html
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Who decides? Mom can give X Dad can give X or y If dad gives X with mom’s X = girl If dad give y with mom’s X = boy __________ determines sex of babies. X y X X y y X DAD
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Thomas Morgan’s experiments with fruit flies PURE RED-EYED WHITE-EYED FEMALESMALES http://www.accessexcellence.org/RC/VL/GG/sex.html X GOT ALL RED EYED FLIES 50% males 50% females
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XXRR XXRR XXRr XXRr XyRR XyRR XyRr XyRr XyRr XyRr Xyrr Xyrr XXRr XXRr XXrr XXrr XR yR yr Xr XR XR Xr Xr RED-EYED FEMALES WHITE-EYED MALES RED-EYED MALES WHITE-EYED FEMALES MORGAN EXPECTED:
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Thomas Morgan’s experiments with fruit flies ACTUAL RESULTS from cross: RED EYED FEMALES RED EYED MALES WHITE EYED MALES NO WHITE EYED FEMALES! http://www.accessexcellence.org/RC/VL/GG/sex.html
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GENE FOR EYE COLOR in Fruit flies IS CARRIED ON X CHROMOSOME So it acts as a single gene cross Image modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
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X R X R X R X R X R X r X R X r X R y X R y X r y X r y XRXRyyXRXRyy X R X R X r X r NO WHITE-EYED FEMALES RESULTS:
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When traits do not appear in expected ratios…. they may be linked. Genes located on the same chromosome form a ______________ group LINKAGE
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X-linked genes are carried on the X CHROMOSOME X-linked recessive disorders show up MORE frequently in _________________ X-LINKED RECESSIVE DISORDERS Color blindness Hemophilia Muscular dystrophy X*X* X X*X* y MALES
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FEMALES CAN BE CARRIERS for X-linked recessive disorders Females need 2 copies of the mutant gene to show the disorder X*X* X X*X*X*X* PERSONS that carry a gene for a recessive disorder but DON’T show the disorder themselves are called __________________ CARRIERS
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CARRIER Carriers DON’T SHOW the trait themselves but can pass it on to their offspring DEFECTIVENORMAL Image modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
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CARRIER ONLY FEMALES can be carriers for X-linked recessive disorders Females have TWO X’s. DEFECTIVE NORMAL Image modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
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CARRIER Males CAN’T be carriers for X-LINKED RECESSIVE disorders Only have one X chromosome NORMAL DEFECTIVE Image modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
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BOTH MALES and FEMALES can be carriers for _______________________ genes. AUTOSOMAL RECESSIVE DEFECTIVE GENE NORMAL AUTOSOMAL RECESSIVE DISORDERS Phenylketonuria Cystic fibrosis Albinism Image modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
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GENES are more complicated than MENDEL thought GENES can change places CROSSING OVER http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
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Gametes get different gene combinations Image modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
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GENES that are _________________ are _________ likely to separate during crossing over in meiosis. FARTHER APART MORE Image modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
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GENES that are _________________ are _________ likely to separate during crossing over in meiosis. CLOSE TOGETHER LESS Image modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
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We can tell where genes are on a chromosome by seeing how often they cross over. Geneticists use crossing over frequency to make a ____________________ that shows the location of genes along a chromosome Chromosome map
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SEX-LINKED and SEX INFLUENCED TRAITS http://biology.clc.uc.edu/courses/bio105/geneprob.htm http://www.people.virginia.edu/~rjh9u/hairears.html
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SEX LINKED TRAITS show up in different % in males and females because they move with the sex chromosomes
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Sex chromosomes can carry other genes X-LINKED GENES: Genes carried on the X chromosome EX: _____________ _____________ _________________________ Hemophilia Colorblindness Duchenne Muscular Dystrophy
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Sex chromosomes can carry other genes Y-LINKED GENES: Genes carried on Y chromosome EX: Hairy pinna _________genes only show up in _______ Y linkedmales. Image from: http://www.people.virginia.edu/~rjh9u/hairears.html
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SEX INFLUENCED TRAITS Genes that are carried on ______________ BUT are affected by the ____________ of the individual that has the gene AUTOSOMES sex hormones
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Male Pattern Baldness Autosomal dominant gene http://biology.clc.uc.edu/courses/bio105/geneprob.htm
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YOUR SEX CHANGES THE EXPRESSION OF THE GENE B is dominant for baldness B’ is recessive for not bald If you are MALE:If you are FEMALE: BB = BB= BB’ = BB’= B’B’ = B’B’= BALD NOT bald BALD NOT bald
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PEDIGREES can help show how are genes passed on over generations
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PEDIGREE CHART Normal Male = Normal Female = Has trait = Carrier = Images modified from: http://www.beavton.k12.or.us/sunset/academics/genetics.htm
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http://www.beavton.k12.or.us/sunset/academics/genetics.htm
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http://www.ikm.jmu.edu/Buttsjl/ISAT493/Hemophilia/hemophiliaeurope.html
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How can we detect disorders? BEFORE BIRTH Amniocentesis Chorionic Villi Sampling (CVS) Karyotype (need to get cells by Amnio/CVS 1 st ) Alpha feto protein (AFP) AFTER BIRTH PKU
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How can we detect disorders ? Insert needle into sac around baby and withdraw fluid containing baby’s cells Done at 14-16 weeks Karyotype can detect:missing/extra chromosomes Other tests can detect: Huntington’s; Cystic Fibrosis Image from: http://www.fiu.edu/~srose/pregchildbirth.doc
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Chorionic Villi Sampling Done at EARLIER (8-10 weeks) Greater chance of miscarriage than with amniocentesis Insert needle and take a sample of sack baby is growing in Can detect same disorders as amniocentesis but sooner Image from: http://www.nlm.nih.gov/medlineplus/ency/imagepages/9181.htm
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Karyotype- ( need cells from baby) Can tell missing/extra chromosomes Gender Some deletions/additions Can’t show point/frame shift mutations Image from: http://members.tripod.com/~yenial/chromosome.html
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ALPHA FETO PROTEIN Test MOTHER’s blood during pregnancy Measures AFP protein made by baby that crosses over into mother’s blood Low AFP = possible Down/Turner syndrome High AFP = Spina bifida http://www.androusa.com/Blood%20Tubes.jpg
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PKU Phenylketonuria Blood test given to ALL babies before leaving hospital Special diet can prevent mental retardation http://www.androusa.com/Blood%20Tubes.jpg http://www2.coca-cola.com/presscenter/img/imagebrands/downloads/lg_dietcoke_can.jpg
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