CHISOM AMAEFUNA ADELINE LAURENTE 1/29/10 PERIOD 2 Sickle Cell Anemia

Summary Sickle cell anemia is a genetic blood disease due to a abnormal form of a hemoglobin. Hemoglobin is the molecule in the red blood cell that transports oxygen from lungs to the farthest parts of the body Symptoms of sickle cell anemia include: Paleness of the skin Weakness Shortness of breath Heart failure Fact: Couples who are both carriers have a 25% chance of giving a mutated gene to a child Sickle cell anemia is more common in middle eastern countries, Africa, Spanish-speaking countries

SICKLE CELL ANEMIA IS LOCATED IN CHROMOSOME 11 Chromosomes

Inheritance of Sickle Cell Anemia -Sickle cell is inherited in an Autosomal recessive pattern. -autosomal recessive-Genetic condition that appears only in individuals who have received two copies of an autosomal Gene -The gene is on an autosome, a nonsex chromosome -People with one defective gene and one normal gene are carriers

Alleles o Alleles are another form of genes that are located on a part of the chromosomes o Humans have 46 alleles because they are attached to chromosomes o Heterozygous has one dominant and one recessive allele o Homozygous has either two dominant or two recessive alleles o Heterozygous: Rr o Homozygous: RR or rr o Dominance one parent has a faulty dominant gene which overpowers the other genes and will make the child either affected or not affected, but not a carrier. o Recessive is when both parents have a normal gene and a affected one. The parents will be carriers but not affected. Their offspring however will either be affected, not affected, or a carrier.

Punnett squares SS Ss SSSs SSSs ss SSSs ss SS S s ss S s S s S S Ss S s

Probability of Punnett squares RATIOS PERCENTAGES 25% SS: 50% Ss: 25% ss S s S SS Ss s Ss ss Homozygous Dominant Heterozygous Dominant Homozygous Recessive 1 : 2 :1 1SS : 2Ss :1ss

Genotype and Phenotype GENOTYPE What is in the GENES S represents dominant allele GREEN s represents recessive allele yellow SS=homozygous dominant (GREEN) Ss= heterozygous dominant (GREEN) ss= homozygous recessive (yellow) 25%: 50% : 25% Normal to carrier to affected PHENOTYPE What you can SEE SS= GREEN Ss= Green (yellow gene carrier) Ss= yellow 3:1 Normal to affected

Genotype and Phenotype Probablilty

Student Practice with Punnett Squares

Pedigree

1. WHY DON’T ANY OF THE SECOND GENERATION CHILDREN HAVE FULL SICKLE CELL ANEMIA? 2. HOW MANY PEOPLE IN THIS PEDIGREE ARE CARRIERS OF SICKLE CELL ANEMIA? 3. HOW MANY PEOPLE IN THIS PEDIGREE SHOW NO SYMPTOMS OF SICKLE CELL ANEMIA? Student Practice with Pedigree