1. A pedigree is a diagram that shows how a trait
is passed in families over many generations

3. ______________

4. Failure of homologous chromosomes to separate during during MEIOSIS
= _________________________
One cell gets 2 copies of
the chromosome;
the other cell
gets none.

5. Normal Meiosis Nondisjunction

6. Nondisjunction

7. Down syndrome (= ____________)

8. Down syndrome (Trisomy 21)
1 in 800 births
Similar facial features
Slanted eyes
Protruding tongue

9. Down syndrome (Trisomy 21)
Simian line on palm

10. Down syndrome (Trisomy 21)
Most common chromosomal abnormality
50% have heart defects that need surgery to repair
Mild to severe mental retardation
Increases susceptibility to many diseases
Risk of having a child with Down syndrome increases with age of mom

11. Phenylketonuria (PKU)
Mutation in gene for an enzyme that breaks down an __________(phenylalanine)
Build up in brain causes mental retardation
ALL babies
are tested for
PKU before they
leave the hospital.
Need a special diet low in __________to extend life and prevent mental retardation
amino acid

12. THINK ABOUT IT So why put a warning label on “sugar free” foods?
There’s not a lot of protein in Diet pop !
The artificial sugar ( _________ ) is made with phenylalanine

13. SICKLE CELL ANEMIA AUTOSOMAL CODOMINANT
Substitution A changed to T in gene for
____________
(protein in red blood cells
that carries oxygen in blood)
Circulatory problems
Cells stick in capillaries
Loss of blood cells (anemia)
Organ damage (brain, heart,spleen)
Can lead to DEATH

14. SICKLE CELL DISEASE SYMPTOMS:
_____________ become sickle shaped in persons with ______
sickle cell ________

15. SICKLE CELL DISEASE Circulatory problems Cells stick in capillaries
Loss of blood cells (anemia)
Organ damage (brain, heart, spleen)
Can lead to DEATH

16. SICKLE CELL DISEASE More common in _________________
1 in 500 = have sickle cell disease
1 in 10 = carriers for allele
Why do so many African Americans carry the sickle cell allele?
Why don’t these awful genetic disorders disappear from the population if having the disorder is can cause death?

17. SICKLE CELL DISEASE Many can trace their ancestry to west
central Africa where ___________,
a serious parasitic disease that
infects red blood cells is common.
Watch a video about
sickle cell and malaria
Images from:

18. A person who is __________________ for the ____________allele (ss) will have _______________
A person who is _________________ for normal hemoglobin alleles will have normal blood cells, but can become infected with __________ (SS)
A _________________ person (Ss)
(with one normal/one sickle cell allele) is
generally healthy and has the ADVANTAGE
of being _________ to malaria
sickle cell

19. Deleterious genes stay in the population because there is somebody that benefits = ___________________________
Normal hemoglobin may or may NOT die from malaria
Twice as many people aren’t sick with sickle cell AND are protected from malaria
Sickle cell disease

20. We are finding more and more links between disease resistance and genetic mutation.
Ex: The cystic fibrosis gene protects the body against typhoid fever.
Tay-Sachs gene seems to confer some resistance to tuberculosis.
Changes in the vitamin D receptor increase resistance to tuberculosis but increase the susceptability to osteoporosis.