Amino acids

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Transcript Amino acids

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
Amino
acid 1
sequence of amino acids
Peptide
bond
Amino
acid 2
Amino
acid 3
Amino
acid 4
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:
HbA:
Gl
u
....
HbS:
Val
....
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 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!
ss
AA
or
As
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