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

Aminoacid 1

Aminoacid 2

Aminoacid 3

Aminoacid 4

Peptidebond

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:

Glu

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

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 phenotypeAs sickle cell carrierSs 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 Asssor

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