Thermodynamics and Binding in Hemoglobin

These flashcards cover key concepts related to thermodynamics, protein stability, and the binding dynamics of hemoglobin and globins.

Gibbs free energy, AG, measures the __ from the reaction that is available for performing useful work.

energy

When AG° is negative, the reaction is __; it can provide energy for useful work.

exergonic

If AG° is positive, the reaction is __, meaning it requires energy input.

endergonic

The binding of oxygen to hemoglobin is __, meaning it occurs in a cooperative manner.

cooperative

In the context of thermodynamics, AG = AH - T__ indicates that changes in enthalpy and entropy affect the free energy.

AS

The hydrophobic effect results in __ changes in water when apolar molecules aggregate together.

entropy

A decrease in pH stabilizes the __ state of hemoglobin, which favors oxygen release.

T

The __ effect refers to the phenomenon where increased CO2 levels lead to enhanced oxygen delivery to tissues due to decreased pH.

Bohr

When mutations alter the amino acid composition of hemoglobin, it can lead to conditions such as __ cell anemia.

sickle

The large fiber formation in sickle cell hemoglobin is caused by the presence of __ in the B subunit instead of glutamate.

valine

Oxygen has a low solubility in blood; hence it is held by __ in muscle.

myoglobin

The reaction of hemoglobin binding oxygen is represented by the __ dissociation constant, P50.

dissociation

In dynamic equilibrium, the fraction of proteins that are folded is often determined by the __ constant, Kfold.

equilibrium

BPG binds to hemoglobin and stabilizes the __ state, which is important under low oxygen conditions.

T

In hemoglobin, a single O₂ binding event can result in a conformational change in the entire __.

tetramer

Protonation of hemoglobin can alter its binding affinity for oxygen; this is known as __ modulation.

heterotropic

The proximal histidine helps stabilize the iron in the __ complex of hemoglobin.

heme

The __ effect states that binding of one O₂ increases the likelihood of other O₂ molecules binding to hemoglobin.

cooperativity

A high value of AG indicates that the reaction is __ and products are favored.

favorable

The adaptation of the sickle-cell trait to reduce malaria infection demonstrates the concept of __ benefits in genetics.

adaptive

In a test tube, if the concentrations of reactants and products remain unchanged, we can say that the system is at __ equilibrium.

dynamic