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HUMAN GENETICS

HUMAN GENETICS. Cleft chin. Tongue Folders. Widow’s Peak. Hitch hiker vs. normal thumb. Bent little fingers. Mid-digital hair. Six fingers/toes????. Interlaced Fingers right over left or left over right???. PEDIGREE SYMBOLS. Autosomal Recessive Diseases. Diseases like: Cystic Fibrosis

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HUMAN GENETICS

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  1. HUMAN GENETICS

  2. Cleft chin

  3. Tongue Folders

  4. Widow’s Peak Hitch hiker vs. normal thumb Bent little fingers

  5. Mid-digital hair

  6. Six fingers/toes????

  7. Interlaced Fingers right over left or left over right???

  8. PEDIGREE SYMBOLS

  9. Autosomal Recessive Diseases Diseases like:Cystic Fibrosis TaySachs Phenylketonuria (PKU) Using a Punnett square, cross two carrier parents of Cystic Fibrosis—Write out your results for Phenotype & Genotype

  10. N n GR: 25% NN 50% Nn 25% nn PR: 75% normal 25% Cystic Fibrosis NN Nn N Nn nn n • 25% chance of child having CF— • 50% chance of child being a carrier of CF--

  11. CYSTIC FIBROSIS Mutation in Chromosome 7 that causes a defective protein in the plasma membrane. Causes the formation of thick mucus in the lungs and digestive tract. This young girl is getting a treatment to remove some of the mucus. Most common in white Americans—one in 28 carries the recessive allele.

  12. Tay Sachs— Recessive allele causes the absence of an enzyme that breaks down a lipid in the CNS. More common in the Jewish population! Infant becomes blind, deaf and has inability to swallow! Usually do not live past 3 years.

  13. PKU--Phenylketonuria What is PKU?Individuals with PKU cannot process a part of protein called phenylalanine, which is present in most foods. Because of a genetic abnormality, affected individuals lack or have very low levels of an enzyme (phenylalanine hydroxylase or PAH) that converts phenylalanine to other substances the body needs. Without treatment, phenylalanine builds up in the bloodstream and causes brain damage and mental retardation.

  14. How does PKU affect a child?Children born with PKU appear normal for the first few months. If untreated, by 3 to 6 months they begin to lose interest in their surroundings. By the time they are 1 year old, they appear obviously developmentally delayed. Children with untreated PKU often are irritable and have behavioral problems. They may have a musty odor about them, and they may have dry skin, rashes or seizures. They usually are physically well developed and tend to have blonder hair than their siblings.

  15. Who gets PKU?Genes come in pairs. To inherit PKU, a child must receive two abnormal PAH genes (that regulate the production of the enzyme), one from each parent who has a mutation (change) in one PAH gene. A parent who has one abnormal PAH gene is called a "carrier." A carrier has one normal PAH gene and one PAH gene that contains a mutation. A carrier's health is not affected in any known way. When both parents are carriers, there is: A 1-in-4 (25 percent) chance that both will pass one abnormal PAH gene on to a child, causing the child to be born with PKU. A 2-in-4 (50-50) chance that the baby will inherit one abnormal PAH gene from one parent and the normal gene from the other, making it a carrier like its parents. A 1-in-4 (25 percent) chance that both parents will pass on the normal gene. The baby will neither have the disease nor be a carrier.  These chances are the same for each pregnancy.

  16. Are all babies tested for PKU?All states and U.S. territories screen for PKU. Babies are tested before they leave the hospital. The PKU test was the nation's first newborn screening test. Developed with the help of the March of Dimes, the test has been routinely administered since the 1960s, sparing thousands of children from mental retardation (2).

  17. Can PKU symptoms be prevented?Yes. Mental retardation can be prevented if the baby is treated with a special diet that is low in phenylalanine. This diet should be started as soon as possible after birth, ideally within the first seven to 10 days of life (2).  At first, the baby is fed a special formula that contains protein but no phenylalanine. Breast milk or infant formula is used sparingly to supply only as much phenylalanine as the baby needs and can tolerate. Later, certain vegetables, fruits, some grain products (for example, certain cereals and noodles) and other low-phenylalanine foods are added to the diet. No regular milk, cheese, eggs, meat, fish and other high protein foods are ever allowed. Diet drinks and foods that contain the artificial sweetener aspartame (which contains phenylalanine and is sold as Nutrasweet or Equal) must be strictly avoided. The diet for each person must be individualized, depending upon how much phenylalanine can be tolerated. All affected persons need regular blood tests to measure phenylalanine levels. Testing for babies may be as frequent as once a week for the first year of life, and then once or twice a month throughout childhood. Individuals with PKU must remain on a restricted diet throughout childhood and adolescence and generally for life (although some relaxation of the diet may be possible as the person ages) (2).

  18. Albinism—Caused by “recessive” alleles--

  19. Albino Moose

  20. Black Bear with Partial Albino Cub

  21. Albino Alligator

  22. Autosomal Dominant Condition Disease like: Huntington’s Disease Cross a homozygous recessive parent with a heterozygous parent—Use a punnett square and show results for Genotype and Phenotype.

  23. H h GR: 50% Hh 50% hh PR: 50% H. Disease 50% Normal hh Hh h hh h Hh 50% chance of H. Disease Carrier 50% chance of Huntington’s Disease

  24. Definition—HUNTINGTON’S DISEASE Huntington's disease is a progressive, degenerative disease that causes certain nerve cells in your brain to waste away. As a result, you may experience uncontrolled movements, emotional disturbances and mental deterioration. Huntington's disease is an inherited disease. Signs and symptoms usually develop in middle age. Younger people with Huntington's disease often have a more severe case, and their symptoms may progress more quickly. Rarely, children may develop this condition. Also called Huntington's chorea, Huntington's disease was documented in 1872 by American physician George Huntington. The name "chorea" comes from the Greek word for "dance" and refers to the incessant quick, jerky, involuntary movements that are characteristic of this condition. Medications are available to help manage the signs and symptoms of Huntington's disease, but treatments can't prevent the physical and mental decline associated with the condition.

  25. The human achondroplasia phenotype, illustrated by a family of five sisters and two brothers. The phenotype is determined by a dominant allele. Also called Dwarfism !

  26. Codominance –Sickle Cell Anemia-- • Work with your partner to answer the following: Chap 12 • How is this disease codominant? • What is the effect of being heterozygous? • What population is affected most? • What is the mutation that causes SCA? • How common is this disease? • How do SCA patients avoid the effects of malaria?

  27. Codominance—Roan color horse-- Red and white hairs! Red Roan Black and white hairs! Blue Roan

  28. Anopheles Mosquito Injects……. Plasmodium into blood……. CAUSES MALARIA—FEVER, CHILLS, LOSS OF APPETITE, DEATH . KILLS 1 MILLION TO 2.5 MILLION PEOPLE PER YEAR---AFRICA Sickle cell trait is the genetic condition selected for in regions of endemic malaria People with normal hemoglobin (2 normal genes=SS) are susceptible to Plasmodium and thus can be infected with malaria and die. People with sickle cell disease (2 sickle genes=ss) are susceptible to death from sickle cell disease.People with one sickle cell trait and one normal trait (heterozygous=Ss), have a much greater chance of surviving malaria and are not affected by the adverse effects of sickle cell disease. (SS=no sickle cells, Ss=some sickle cells, ss=sickle cells)

  29. Multiple Gene (Polygenic) Inheritance Polygenic Inheritance:Human skin color is a good example of polygenic (multiple gene) inheritance. Assume that three "dominant" capital letter genes (A, B and C) control dark pigmentation because more melanin is produced. The "recessive"alleles of these three genes (a, b & c) control light pigmentation because lower amounts of melanin are produced.

  30. Multiple Alleles—When more than two alleles are possible for the same trait!!! Example: Blood Types

  31. What is blood made up of? An adult human has about 4–6 liters of blood circulating in the body. Among other things, blood transports oxygen to various parts of the body. Blood consists of several types of cells floating around in a fluid called plasma.The red blood cells contain hemoglobin, a protein that binds oxygen. Red blood cells transport oxygen to, and remove carbon dioxide from, the body tissues.The white blood cells fight infection.The platelets help the blood to clot, if you get a wound.The plasma contains salts and various kinds of proteins.

  32. Multiple Alleles—Blood types are determined by more than 2 alleles. A is dominant to O. B is dominant to O. A and B are co-dominant. i i IAIA or IAi IBIB or IBi IAIB OR

  33. Sample Blood Type Problems ------------------------------------

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