human inheritance abo blood groups and genetic disorders
TRANSCRIPT
Important Vocabulary
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
Slide #2
Variations in Alleles
1. Variations in traits arise from mutations
2. Many mutations produce genes that don’t functiona. 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
Slide #3
ABO Blood Groups
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 bothare present
Slide # 4
Cystic Fibrosis1.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
Slide # 7
Sickle-Cell Anemia1. Mode of inheritance a. recessive allele on
chromosome # 112. 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 10-20 days
8 to 10% African Americans are carriers
Slide # 8
Tay Sachs1. Mode of Inheritance a. recessive allele on
chromosome # 152. 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 53. Carriers resistant to
tuberculosis
11% of Jewish population are carriers
Also common in French-Canadians &
Cajuns
Slide # 9
PKU1. 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.
Slide # 10
Huntington’s Disorder
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 35- 45 years of age
Slide # 11
Important Vocabulary
1. Autosome: a regular body chromosome (# 1 - 22)
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
Slide # 13
Sex Linked Traits1. 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.
Slide # 14
Hemophilia
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.
Slide # 15