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

http://www.beavton.k12.or.us/sunset/academics/genetics.htm

______________ http://www.ikm.jmu.edu/Buttsjl/ISAT493/Hemophilia/hemophiliaeurope.html

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

Normal Meiosis Nondisjunction http://web.udl.es/usuaris/e4650869/docencia/gen_etica/meioferti2.html http://www.tokyo-med.ac.jp/genet/anm/domov.gif

Nondisjunction

Down syndrome (= ____________)

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

Down syndrome (Trisomy 21) Simian line on palm

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

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 http://biology.clc.uc.edu/courses/bio104/protein.htm

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

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

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

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

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?

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: http://en.wikipedia.org/wiki/Malaria

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

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

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.