1. Complex Inheritance and Human Heredity
Chapter 11
Complex Inheritance and Human Heredity

2. 11.1 Basic Patterns of Human Inheritance
The inheritance of a trait over several generations can be shown in a pedigree
Pedigrees can help us to track and understand genetic disorders

3. Genetic Disorders Review: HH= homozygous dominant Hh= heterozygous
hh= homozygous recessive
A recessive trait is only expressed if it is homozygous recessive
If an individual is heterozygous for a recessive disorder, they are called a carrier.

4. Types of Recessive Genetic Disorders:
Cystic Fibrosis
Affects the mucus-producing glands, digestive enzymes, and sweat glands
Chloride ions are not absorbed into the cells of a person with cystic fibrosis but are excreted in sweat
Without sufficient chloride ions in the cells, a thick mucus is secreted

5. Location of the CF gene on chromosome 7

6. Breathing Treatment for CF

7. Albinism
Caused by altered genes, resulting in the absence of pigment in the skin and eyes
White hair
Very pale skin
Pink iris

8. Tay-Sachs Disease
Caused by the absence of the enzyme responsible for breaking down fatty acids called gangliosides
Gangliosides accumulate in the brain, inflating brain nerve cells and causing mental deterioration.

9. Dominant Genetic Disorders
You can be either heterozygous or homozygous dominant to inherit a dominant genetic disorder.

10. Huntington’s disease Affects the nervous system
Caused by a genetic defect on chromosome 4
Section of DNA repeats too many times
As the gene is passed down from one generation to the next, the number of repeats gets larger
This means that the symptoms develop at younger and younger ages.

11. Achondroplasia
Genetic condition that causes small body size and limbs that are comparatively short

12. Pedigrees
A diagram that traces the inheritance of a particular trait through several generations

13. Pedigree Symbols Normal Female Female that expresses the trait
Female carrier (half shaded)
Normal male
Male that expresses the trait
Male who is a carrier for the trait

14. Pedigree Symbols Roman Numerals (I, II, III, etc.) = Generation number
Arabic numbers (1,2,3, etc) = individuals in a particular generation

15. Pedigree I II
III