1. Chapter 8 -

2. Mendalian Genetics Review

3. Incomplete Dominance vs. Codominance
Incomplete Dominance: one trait is not completely dominant over the other
Two identical copies of a dominant allele are required for expression (homozygous)
Heterozygous situations create an intermediate (mixture of traits)

4. Incomplete Dominance vs. Codominance
Codominance: two dominant traits appear in the phenotype
Two identical copies of a dominant allele are required for expression (homozygous)
Heterozygous situations create a combination of two traits

5. ABO Blood System
ABO blood system uses surface markers (carbohydrates) of red blood cells
The system shows relatedness of people
ABO blood typing displays:
Multiple Allelism: more than two alleles of a gene are in the population
Type A, Type B, & Type O
Codominance:
Type A & B are dominant, Type O is recessive

7. Polygenic vs. Pleiotropic Traits
Polygenic traits: genetic traits affected by many genes
Skin Color
Eye Color
Height:
Leg bone height
Torso height

8. Polygenic vs. Pleiotropic Traits
Pleiotropic traits: a single gene causing multiple effects
Hemophilia – cannot produce clotting factor VIII; unable to form clots to stop bleeding
Excessive Bruising
Pain
Swelling in the joints

9. Sex Determination For sex chromosomes:
Males have one X & one Y
Females have two X’s
Males produce gametes (sperm cells), half contain one X chromosome and the other half contain one Y chromosome
Females produce gametes (egg cells), all contain one X chromosome
All fertilized eggs have an X chromosome from the female and either an X or Y chromosome from the male

10. Sex-linked vs. Autosomal Gene Inheritance
Autosomal gene: gene that is located on a chromosome that is not a sex chromosome
Sex-linked gene: gene that is located on the X or Y chromosome, which makes it associated with gender
Example
In hemophilia (h), it is a faulty gene only on the X chromosome
The hemophilia gene is a recessive condition
Men have the condition if they get the faulty gene since they only have one X chromosome
Women only have the condition if they have two faulty genes

11. X-linked Hemophilia

12. X-inactivation & Inheritance
An extra chromosome on number 21 produces a condition called Down’s Syndrome
An extra chromosome on number 18 results in early death in the womb or as an infant
Triple X Syndrome occurs when there is an extra X chromsome in females
No major development symptoms
Why?
X-inactivation: genes from multiple X chromosomes are not expressed, resulting in normal developments and phenotypes
This occurs normally in females, who have two X chromosomes

13. Use of Pedigrees in Science
Pedigrees are family trees that show inheritance of genetic traits for many generations
Scientists use pedigrees to study the inheritance of a genetic traits & genetic disorders

14. DNA Fingerprinting
DNA Fingerprinting: Process by which DNA from different sources is compared.
When small amounts of DNA are available, polymerase chain reaction (PCR) can be used to make millions of copies of the DNA
DNA is cut and separated on an gel (made from agarose) with an electric current
DNA is compared to show related ness