Chapter 7 Flashcards
What is hyperbolic and sigmoidal?
Hyperbolic- one protein, one ligand
Sigmoidal- one protein, multiple ligands
What are the two models of cooperative binding?
Concerted model and sequential model.
What is sickle cell anemia and what are its effects?
A mutation in the amino acid sequence of hemoglobin. The exchange of oxygen is inefficient, people with the disease become weak, dizzy, s.o.b, etc
Sickle cells rupture easily, resulting in anemia.
What mutations cause aggregation in sickle cell anemia?
A single glutamic acid to valine mutation
What is a Hill Plot, and what is the Hill coefficient?
When is ligand binding cooperative and when is it not? What about hemoglobin binding to O2?
The slope of the Hill Plot is n sub H. This is called the Hill coefficient, which measures the degree of cooperativity. If nH=1, ligand binding is not cooperative. If nH>1, positive cooperativity. If nH<1, negative cooperativity, this is more difficult to bind to ligand. Hemoglobin binding to O2 is hard, so nH<1. There is cooperative binding if there is more than 1 binding site.
What kind of effect does pH have on oxygen binding to hemoglobin?
(Bohr Effect) Hemoglobin binds H+ and CO2, and this binding is inversely proportional to the binding of O2.
Low pH- high CO2 levels, so the affinity of hemoglobin for O2 decreases and increases for CO2.
High pH- As blood pH rises, the opposite effect occurs. The affinity of hemoglobin for O2 increases and decreases for CO2.
What are the two confirmations of hemoglobin and what do they do? What happens with binding of O2 in each state?
R state is bound hemoglobin to oxygen “relaxed state”, T state is unbound hemoglobin to oxygen “deoxy”, “tense state”
R state- binds oxygen more easily than T states. This is the “relaxed” state, where O2 is bound.
T state- more stable and is called deoxyhemoglobin, because it’s stabilized by a greater number of ion pairs. Binding of O2 changes the confirmation to the R state. This is the “tense” state, where O2 is not bound.
What are the six steps in ELISA? What happens when there is a color change?
When there is a color change, the secondary antibody enzyme binds to the primary antibody.
- Coat surface with sample (antigens)
- Block unoccupied sites with nonspecific protein.
- Incubate with primary antibody against specific antigen.
- Incubate secondary antibody-enzyme complex that binds primary antibody.
- Add substrate.
- Formation of colored product indicates presence of specific antigen.
What are the four steps in the mechanism of muscle contraction?
- ATP binds to myosin head, causing dissociation from actin.
- Tightly bound ATP is hydrolyzed, and a conformation change occurs. ADP and Pi remain associated with the myosin head.
- Myosin head attaches to actin filament, causing release of Pi.
- Pi release triggers a “power stroke”, a conformational change in the myosin head that moves actin and myosin filaments relative to one another. ADP is released in the process.
What does a sequential model look like?
What does a concerted model look like?
