1. ABO Blood Groups and Genetic Disorders
Human Inheritance
ABO Blood Groups and Genetic Disorders

2. Important Vocabulary
Slide #2
1. Carrier: someone who is heterozygous for a trait
2. Multiple alleles: traits that have more than 2 possible alleles; still only inherit 2 alleles
3. Co-dominance: when two different alleles are present and BOTH alleles are expressed.
4. Mutation: a change in an organism’s DNA; changes how a gene functions
a. leads to 2 or more alleles for a given trait

3. Variations in Alleles 1. Variations in traits arise from mutations
Slide #3
Variations in Alleles
1. Variations in traits arise from mutations
2. Many mutations produce genes that don’t function a. most of these mutations produce non-functioning proteins
b. non functioning proteins can cause lethal genetic defects
c. sometimes mutations produce proteins that have different functions

4. ABO Blood Groups 1. Multiple alleles
Slide # 4
1. Multiple alleles
a. 3 different alleles; IA, IB, & i
b. 6 genotypes / 4 phenotypes
IA IA or IA i = Type A
IB IB or IB i = Type B
IA IB = Type AB
i i = Type O
2. IA and IB are co-dominant; both are expressed if both are present

5. Guide to who can give and who can receive in donating blood
Slide # 6
Guide to who can give and who can receive in donating blood

6. Genetic Disorders are caused by defective genes.
Defective genes arise from mutations in DNA.

7. Cystic Fibrosis 1. Mode of inheritance
Slide # 7
1. Mode of inheritance
a. recessive allele on chromosome # 7
2. Symptoms:
a. thick mucus forms in lungs & digestive tract
b. Affected people have trouble breathing; contract lung infections easily
c. Affected people live to be about 30 years old
1 in 25 Caucasians in US are carriers
1 in 2500 are affected

8. 8 to 10% African Americans are carriers
Sickle-Cell Anemia
Slide # 8
1. Mode of inheritance
a. recessive allele on chromosome # 11
2. Symptoms
a. blood cells become sickle shaped; don’t carry oxygen
b. sickle shaped cells clog blood vessels & cause pain & swelling
c. Affected persons live to be about 50
3. Carriers are resistant to malaria
Normal blood cells live 120 days
Sickle-shaped blood cells live days
8 to 10% African Americans are carriers

9. Tay Sachs 1. Mode of Inheritance
Slide # 9
Tay Sachs
1. Mode of Inheritance
a. recessive allele on chromosome # 15
2. Symptoms
a. Fatty substance builds up in nerve cells in brain
b. Gradual paralysis & loss of nerve function
c. Affected children die by age 4 or 5
3. Carriers resistant to tuberculosis
11% of Jewish population are carriers
Also common in French-Canadians & Cajuns

10. PKU 1. Mode of Inheritance a. recessive allele on chromosome # 12
Slide # 10
PKU
1. Mode of Inheritance
a. recessive allele on chromosome # 12
2. Symptoms
a. body does not break down phenylalanine
b. high level of phenylalanine interferes with nervous system development; leads to mental retardation
c. Easily treated by following strict diet
d. all newborns tested for PKU
Foods farthest away from the target must be avoided.

11. Huntington’s Disorder
Slide # 11
1. Mode of inheritance
a. dominant allele on chromosome # 4
2. Symptoms
a. brain cells slowly break down; causes jerking muscles, slurred speech, difficulty swallowing, loss of balance, reasoning & memory loss, & eventually death
b. Symptoms usually begin at years of age

12. Sex-linked traits: Genes located on the sex chromosomes.

13. Important Vocabulary 1. Autosome: a regular body chromosome (# 1 - 22)
Slide # 13
Important Vocabulary
1. Autosome: a regular body chromosome (# )
2. Sex chromosome: chromosome that determines the sex of an individual; X & Y
a. XX = female
b. XY = male
c. The sex chromosomes are # 23

14. Slide # 14
Sex Linked Traits
1. Sex-linked trait: A trait that is determined by a gene found on one of the sex chromosomes.
2. Occur more often in males because males only receive one X chromosome (one copy of the gene).
3. Fathers pass the X chromosome on to daughters only.
4. Mothers pass an X chromosome on to sons and daughters.
5. Females must receive 2 copies of the defective gene to show the trait.

15. Hemophilia 1. Mode of inheritance a. recessive allele on X chromosome
Slide # 15
1. Mode of inheritance
a. recessive allele on X chromosome
2. Main Symptom
a. blood fails to clot properly
b. may bleed internally – especially at the knees and elbows
Hemophilia can be traced through a pedigree of the royal family.

16. Color-blindness 1. Mode of Inheritance
Slide # 16
1. Mode of Inheritance
a. recessive allele on X chromosome
2. Symptoms
a. inability to distinguish red and green colors
b. Normal life span