1. ~Please Staple Your Bibliography to your Rubric. ~If you present today keep everything at your desk and you will turn in when you present. ~If you present next session, tape your flash drive to the bottom of your bibliography and turn in.

2. Please pick up a copy of the notes (2 sheets)on the front desk. Place your homework in the basket. Warmup ~ Hemophilia is an x-linked recessive trait. Use “H” or “h.” A man with hemophilia and a woman who is normal and a non carrier have 4 daughters. How many of them are likely to be carriers for hemophilia?

3. Human Genetics

4. Studying Human Inheritance Biologists study how traits are inherited by studying the phenotypes in a family from generation to generation. A pedigree is used to record and compare phenotypes between generations. Studying pedigrees usually show patterns of inheritance that occur (repeating patterns).

5. Human Inheritance Individuals who have only one copy of a recessive autosomal allele are carriers. Carriers do not usually express the recessive allele but they do pass it on.

6. Genetic Traits and Disorders Genetic Disorders are diseases of debilitating conditions that have a genetic basis. Single-allele traits are controlled by a single dominant allele. –More than 200 human traits are dominated by a single dominant trait.

7. Genetic Traits and Disorders Multiple Allele Traits are controlled by 3 or more alleles. –Example: Human blood types are controlled by 2 of 3 different alleles I A I B and i. Polygenic Traits – Traits that are controlled by multiple genes. –Example: Eye color, skin color, height. –Some can be modified by environmental factors as well.

8. Genetic Traits and Disorders X-linked traits –Examples Colorblindness – occurs in 8% of males Hemophilia – Impairs the ability of blood to clot. Duchenne Muscular Dystrophy – weakens and progressively destroys muscle tissue.

9. Color Blindness Test

11. Genetic Traits and Disorders Sex-Influenced Traits –The presence of male and female hormones affects the expression of certain traits. –Males and females have different phenotypes even when they share the same genotype. –Example: Baldness. A heterozygous male will be bald but a heterozygous female will not be. This is due to the presence of gender specific hormones.

12. Genetic Traits and Disorders Huntington’s Disease is caused by a dominant allele on an autosome (autosomal-dominant pattern of inheritance). –1 st Characterized by forgetfulness and irritability in 30’s to 40’s. –Eventually loss of muscle control, physical spasms and severe mental illness followed by death. –Most who carry it do not know until after they’ve had children, therefore continuing to pass it.

13. Genetic Traits and Disorders Recently a genetic marker was discovered that indicates a likelihood of developing Huntington’s Disease. Over 250 other single- allele traits are controlled by homozygous recessive alleles (autosomal recessive pattern of inheritance). –Examples: Cystic Fibrosis and Sickle Cell Anemia

14. Genetic Traits and Disorders Disorders due to nondisjunction. –Nondisjunction occurring during meiosis can cause gametes to lack a chromosome or have an extra chromosome. –Example: An egg may have 22 or 24 chromosomes. If a zygote has only 45 chromosomes then one pair has only one chromosome (monosomy). If a zygote has 47 chromosomes then there are 3 copies of one chromosome (trisomy).

15. Turner Syndrome Nondisjunction

16. Detecting Human Genetic Disorders A person with a poor family history may want to undergo a genetic screening. –This may include a karyotype or blood tests for the presence of certain proteins. Amniocentesis – A sample of amniotic fluid that surrounds the fetus. This may be used to diagnose genetic disorders. Chorionic villi sampling – A sample of tissue that grows between the woman’s uterus and a placenta.

17. Detecting Human Genetic Disorders Phenylketonuria is a genetic disorder where the body cannot metabolize the amino acid phenylalanine. –1 in 10,000 babies are born in the U.S. w/this. –Blood tests can detect it and accommodations may be made through special diets.