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Transcript
KARYOTYPE is a picture of A __________ an organism’s chromosomes Chromosomes that determine the sex of an organism = _________________ Sex chromosomes http://www.angelbabygifts.com/ All other chromosomes = _________________ autosomes Humans have two sex chromosomes X y and _____ 44 autosomes PEDIGREES _______________are diagrams genes are passed that show how are ____________ in families on __________ over several generations Drawing a pedigree chart http://www.beavton.k12.or.us/sunset/academics/genetics.htm http://www.ikm.jmu.edu/Buttsjl/ISAT493/Hemophilia/hemophiliaeurope.html Y-LINKED GENES: carried on Y Genes ______________ chromosome EXAMPLE: Hairy pinna ONLY show up _______ in males Y linked _________genes _____ Chapter 14 SEX DETERMINATION XX = female Xy = male Who decides? Mom can give X Dad can give X or y X X X XX XX y Xy Xy Dad determines sex of the baby. SO ____ If dad gives X with mom’s X = girl If dad give y with mom’s X = boy SEX CHROMOSOMES CAN CARRY OTHER GENES TOO = ___________________ SEX LINKED TRAITS These traits show up in different _______________ in males and females percentages because they move with the sex chromosomes X-LINKED GENES: ____________ are carried on the X chromosome X-linked recessive disorders MORE frequently show up _____________ in MALES ______ than females because males only have ONE X chromosome. ______ Males ONLY HAVE ONE X DEFECTIVE They either have the disorder NORMAL Or They are normal FEMALES HAVE TWO X CHROMOSOMES DEFECTIVE NORMAL DEFECTIVE Females have one normal gene that works. need 2 Females __________ defective recessive alleles to show the disorder THOMAS HUNT MORGAN’S RESULTS HEMOPHILIA CAUSE: Mutation in genes for __________________ Blood clotting proteins on X chromosome carried ______ Blood clotting proteins are missing so person with this disorder can’t stop bleeding when bleed to death from minor injured; can ________________ cuts or suffer internal bleeding from bruises or bumps. HEMOPHILIA Treatment: injections of normal clotting Need ____________ proteins to stop bleeding More common in ______ males because it is _____________ TWO recessive X-linked, but females with ______ hemophilia alleles will also show the trait. 1 in 10,000 males has hemophilia COLORBLINDNESS CAUSE: Mutation in one of three genes for _______________ carried on X chromosome Color vision Persons with this disorder have trouble distinguishing colors. Red-green _________________ colorblindness is most common Seen in 1 in 10 males 1 in 100 females http://gizmodo.com/gadgets/peripherals/samsung-develops-lcd-for-colorblind-036306.php Duchenne Muscular Dystrophy CAUSE: deletion in gene that codes for a muscle protein _______________ Results in progressive weakening ____________________ and loss of skeletal muscle ___________________ http://www.cadenhead.org/workbench/gems/jerry-lewis-telethon.jpg http://www.tokyo-med.ac.jp/genet/chm/dei.gif Duchenne Muscular Dystrophy (DMD) SYMPTOMS: 1 in 3000 male births Appears before age 5 Progressive muscle weakening Most in wheelchair by age 13 Eventually lethal What’s the pattern: Y-linked traits show up _______ ONLY in _______ males ________ X-linked recessive traits: __________________ ______________________ more common in males than females. ________________ ONLY FEMALES can be ________. carriers AUTOSOMAL RECESSIVE traits: _______________________ FEMALES can be ________ carriers BOTH MALES ______ & _________ CHROMOSOMAL Abnormalities ________________ • 1 infant in 200 newborns has a chromosomal abnormality • 28% of first trimester miscarriages have a chromosomal abnormality • Abnormalities in larger chromosomes don’t usually survive CHROMOSOMAL MUTATIONS ____________________________: structure or Change in the ______________ number ____________ of chromosomes Homologous chromosomes fail to separate during MEIOSIS ________________ NONDISJUNCTION = _________________________ One cell gets 2 copies of the chromosome the other cell gets none. Normal Meiosis Nondisjunction http://web.udl.es/usuaris/e4650869/docencia/gen_etica/meioferti2.html http://www.tokyo-med.ac.jp/genet/anm/domov.gif Nondisjunction Nondisjunction Since it happens to a sperm or egg, the new baby can end up 3 copies with _____________ of a chromosome TRISOMY = __________________ OR one copy of a only ___________ chromosome = ___________________ MONOSOMY Human Abnormalities caused by Non-Disjunction __________________ Down syndrome Klinefelter syndrome __________________ Turner syndrome __________________ TRISOMY 21 Down syndrome (= ____________) Down syndrome (Trisomy 21) • 1 in 800 births • Similar facial features • Slanted eyes • Protruding tongue Down syndrome (Trisomy 21) Simian line on palm Down syndrome (Trisomy 21) • Most common chromosomal abnormality • 50% have heart defects that need surgery to repair • Mild to severe mental retardation • Increases susceptibility to many diseases • Risk of having a child with Down syndrome increases with age of mom Turner syndrome XO Turner syndrome ____ • • • • • • • • • 1 in 5000 births Females have only one X chromosome Small size Slightly decreased intelligence 35% have heart abnormalities Hearing loss common Broad chest Reproductive organs don’t develop at puberty Can’t have children http://medgen.genetics.utah.edu/photographs/diseases/high/611.gif Klinefelter syndrome XXy Klinefelter syndrome • 1 in 1000 births • Males have extra X chromosomes (Can be XXy, XXXy, or XXXXy) • Average to slight decrease in intelligence • Small testes/can’t have children • Usually not discovered until puberty when don’t mature like peers Karyotype (need cells from baby) Image from: http://members.tripod.com/~yenial/chromosome.html Can tell __________________ MISSING/EXTRA chromosomes GENDER __________ DELETIONS/INSERTIONS Some _____________________ single gene Can’t see _______________ mutations If having extra chromosomes causes genetic problems, how come having two X chromosomes in females and one X in males is not a problem? X-chromosome Inactivation ONE X chromosome In female cells ______ SWITCHED OFF is randomly ________________ It condenses and forms a dense region in the nucleus called a BARR BODY _____________ http://fig.cox.miami.edu/~cmallery/150/gene/barr.htm CAT COLOR http://www.islandstrolling.com/mainland/peloponnes/photo/mystra_cat_white_orange_black.jpg In cats, a gene that controls the SPOT COLOR _____________ is carried on the X chromosome ____________________ In some female cells the X with the allele for orange spots is switched off and in some cells the X with the allele for black spots is switched off, so cat has different colored spots. CAT COLOR http://ascensionparish.net/forum/messages/14/2493.jpg Male cats have only _________ one X chromosome, so they can only have ____________ one color of spots! THINK ABOUT IT? How many colors of spots could a male cat with Klinefelter syndrome have?