 Unit 3: Seminar Sickle Cell Anemia

Types of Biomolecules Figure 2-17 Molecular Biology of the Cell (© Garland Science 2008)

Amino Acids  Amino acids are the basic subunits of proteins.  Each amino acid contains the following parts:

Amino Acids  20 different types of amino acids typically use in proteins  The “R” group is what makes each unique

Polypeptides  Multiple amino acids are joined together through peptide bonds to form polypeptides.

Protein Structure  The function of a protein is related to its structure.  There are 4 levels of protein structure:

Protein Structure  The function of a protein is related to its structure.  There are 4 levels of protein structure:  Primary  Secondary  Tertiary  Quaternary

Primary Protein Structure  Primary structure = the linear sequence of amino acids Amino acid 1 Amino acid 2 Amino acid 3 Amino acid 4 Peptide bond

Secondary Protein Structure  Secondary structure = folding of polypeptides into alpha-helices or beta-sheets

Tertiary Structure  Tertiary structure = 3-dimensional folded “globular” structure

Quaternary Structure  Quaternary structure = combination of multiple folded polypeptides

Sickle Cell Anemia: Molecular Basis  A single nucleotide polymorphism in the gene for the beta- subunit of hemoglobin  Results in a single amino acid change:

Sickle Cell Anemia: Molecular Basis  A single nucleotide polymorphism in the gene for the beta- subunit of hemoglobin  Results in a single amino acid change: Gl u Val.. HbA: HbS:

Sickle Cell Anemia: Molecular Basis  Normal hemoglobin = the major protein which fills red blood cells

Sickle Cell Anemia: Molecular Basis  Normal hemoglobin = the major protein which fills red blood cells  Carries oxygen from the lungs to body tissues  Carries carbon dioxide away from body tissues to the lungs

Sickle Cell Anemia: Molecular Basis  Normal hemoglobin = the major protein which fills red blood cells  Carries oxygen from the lungs to body tissues  Carries carbon dioxide away from body tissues to the lungs Oxygenated: Deoxygenated: Normal hemoglobin floats free in the RBC.

Sickle Cell Anemia: Molecular Basis  Normal hemoglobin = the major protein which fills red blood cells  Carries oxygen from the lungs to body tissues  Carries carbon dioxide away from body tissues to the lungs Oxygenated: Deoxygenated: Normal hemoglobin floats free in the RBC. HbS sticks together when it becomes deoxygenated, forming long, rigid strands.

Normal vs. Sickle Cell

Sickle Cell Disease

 Consequences:  Anemia (low hemoglobin) due to removal of abnormal RBCs  Fatigue  Shortness of breath  Enlarged spleen  Vaso-occlusion (blockage of blood vessels)  Pain  Necrosis  Stroke  Renal failure

Sickle Cell Gene Distribution  Why is the sickle cell gene (HbS) so prevalent in certain areas of the world?

Sickle Cell Genetics  Each person has two copies of the gene for beta- hemoglobin  A = “normal” dominant form  S = sickle cell, recessive form AA  normal phenotype As  sickle cell carrier Ss  sickle cell disease

Sickle Cell and Malaria  Sickle cell has higher prevalence in regions where malaria is endemic.

HbS and the “Heterozygote Advantage”  Sickle cell actually has a protective effect against malaria! AA Asss or

Sickle Cell Anemia: Treatment  Prevention of sickle cell crisis episodes  Management of symptoms  Bone marrow transplant

Unit 4  Discussion topic: Antibiotics  Lab Project #2: Continue data collection  Test #1: 30 multiple choice questions on units 1-4