PATTERNS OF INHERITANCE AND HUMAN GENETICS BY DAWN M. THOMPSON

  • Published on
    19-Dec-2015

  • View
    212

  • Download
    0

Embed Size (px)

Transcript

<ul><li> Slide 1 </li> <li> PATTERNS OF INHERITANCE AND HUMAN GENETICS BY DAWN M. THOMPSON </li> <li> Slide 2 </li> <li> SIMPLE RECESSIVE INHERITANCE CYSTIC FIBROSIS:CF 1. Common in white Americans 1:2000 2. Caused by defective protein in plasma membrane. 3. Mucus accumulates in lungs and digestive tract. 4. Controlled by physical therapy, diet, drug therapy 5. Life expectancy improving annually 6. Person must have 2 recessive alleles to suffer from CF. 1 allele carrier but shows no symptoms </li> <li> Slide 3 </li> <li> PKU Phenylketouria Caused by the absence of an enzyme that converts the amino acid phenylalanine to tyrosine. Accumulation of phenylalanine leads to mental retardation and CNS damage Newborns are given a blood test to check for the absence of the enzyme Milk products are high in phenylalanine Disorder is treatable by controlling diet from birth </li> <li> Slide 4 </li> <li> OTHER RECESSIVE TRAITS TAY-SACHS ATTACHED EAR LOBES DO PROBLEM SOLVING LAB 12.1 p317 </li> <li> Slide 5 </li> <li> SIMPLE DOMINANT TRAITS HUNTINGTONS DISEASE: 1. Lethal disorder, no treatment 2. Certain areas of the brain breakdown 3. Symptoms; neurological and muscular show at the age of 30+ 4. Genetic testing is available before symptoms show 5. Ethical issues 6. Every child of an affected person has a 50/50 chance of inheriting the disease 7. Only 1 defective allelle required for person to show disease </li> <li> Slide 6 </li> <li> OTHER DOMINANT TRAITS 1. Unattached ear lobes 2. Tongue rolling 3. Hapsburg lip 4. Hitchhikers thumb 5. Hairy fingers 6. Almond shaped eyes 7. Thick lips 8. Widows peak </li> <li> Slide 7 </li> <li> INCOMPLETE DOMINANCE </li> <li> Slide 8 </li> <li> Heterozygous phenotype is intermediate between those of the two homozygotes Red flower x white flower Intermediate phenotype is pink R R R RR F1 RRRR RR RR R F2 </li> <li> Slide 9 </li> <li> CODOMINANCE CODOMINANT ALLELES CAUSE THE PHENOTYPE OF BOTH HOMOZYGOTES TO BE PRODUCED IN THE HETEROZYGOTE INDIVIDUALS. BOTH ALLELES ARE EXPRESSED EQUALLY BW B W BBBW WW B = black feathers in chickens W = white feathers in chickens BB = black chicken BW = checkered chicken WW = white chicken </li> <li> Slide 10 </li> <li> CODOMINANT TRAITS SICKLE-CELL ANEMIA 1. Common among African Americans 1:12 2. Homozygous people for trait differ by 1 amino acid coding for hemoglobin compared to normal people 3. Abnormal hemoglobin is sickle celled 4. Sickle shaped cells block blood vessels reducing the amount of oxygen reaching the tissues 5. Shortened life span </li> <li> Slide 11 </li> <li> HETEROZYGOUS ADVANTAGE People who are heterozygote for the trait produce both normal and abnormal hemoglobin Show no symptoms of sickle- cell anemia Less likely to suffer from malaria This explains why Africans suffer more from sickle-cell anemia </li> <li> Slide 12 </li> <li> MULTIPLE PHENOTYPES FROM MULTIPLE ALLELES Traits controlled by more than two alleles have multiple alleles </li> <li> Slide 13 </li> <li> BLOOD GROUPS ABO blood group Single gene I has 3 different alleles Blood type A genotype I A I A I A i Blood type B genotype I B I B I B i Blood type ABgenotype I A I B (codominant) Blood type O genotype ii (recessive) Important in blood transfusions and paternity suits Refer to ABO blood group information page 325 </li> <li> Slide 14 </li> <li> SEX DETERMINATION Autosomes 22 pairs of homologous chromosomes 23 rd pair of chromosomes are sex chromosomes X and Y Female XX chromosomes Male XY chromosomes Gametes carry either an X or Y chromosome Fertilization results in offspring having either XX or XY chromosomes There is a 50:50 chance of producing a male or female each time an offspring is produced. </li> <li> Slide 15 </li> <li> SEX-LINKED INHERTANCE Experiments conducted by Morgan Worked with Drosophila (fruit flies) Easy to keep: feed on banana, live in a vial, reproduce in a few days, produce large numbers of offspring. Observed males had white eyes more often than females Suggested gene for eye color was carried on the X chromosome and Y chromosome has no corresponding gene for eye color </li> <li> Slide 16 </li> <li> INHERITANCE OF EYE COLOR IN DROSOPHILA </li> <li> Slide 17 </li> <li> COLOR BLINDNESS X-linked disorder Inability to differentiate between two colors such as red and green Males are more susceptible because they have to inherit 1 defective X chromosome to suffer from the disorder females needed to inherit 2 defective chromosomes. Most serious problem is the inability to detect traffic light colors </li> <li> Slide 18 </li> <li> HEMOPHILIA X-linked disorder Caused by a lack of factor VIII a blood clotting enzyme Inability to clot the blood 1:10,000 males 1:100million females Males are more susceptible because they have to inherit 1 defective X chromosome to suffer from the disorder females needed to inherit 2 defective chromosomes. Treated by blood transfusions and injections of factor VIII. Treatments are expensive and some people have contracted AIDS. </li> <li> Slide 19 </li> <li> POLYGENTIC INHERITANCE A trait is controlled by two or more genes. Inheritance of eye color, height, stem length, skin color. Bell shaped curve. </li> <li> Slide 20 </li> <li> ENVIRONMENTAL INFLUENCES Factors that determine how genes or expressed in an organism. External environmental: temperature, light, chemicals, and infectious agents influence gene expression. Temperature determines coat color of artic foxes Internal environmental: males and females differ because of differences in hormones and structures. Horn size in males greater than females. Male pattern baldness and feather color in peacocks is influenced by different hormones in different sexes </li> <li> Slide 21 </li> <li> ENVIRONMENTAL INFLUENCES </li> <li> Slide 22 </li> <li> CHANGES IN CHROMOSOME NUMBERS Nondisjunction: paired chromosomes fail to separate properly during meiosis TRISOMY: 47 chromosomes Downs syndrome: chromosome 21 3 copies inside of 2. Mental retardation etc, higher incidence in women over 40. Klinfelters syndrome: males, extra X or Y chromosome. MONOSOMY: 45 chromosomes Turners syndrome: females, missing X chromosome, mental retardation, sterile. </li> <li> Slide 23 </li> <li> KARYOTYPE Chart of chromosome pairs used to evaluate unusual chromosome numbers in cells. Amniocentesis is the procedure by which the cell are collected for analysis and production of the karyotype. </li> </ul>