Hemoglobin 2

The video explores the concept of cooperativity, focusing on hemoglobin's positive cooperativity, where oxygen binding becomes more favorable with each subsequent oxygen molecule. It discusses structural changes in hemoglobin upon oxygen binding, emphasizing the role of histidine. The Bohr effect is explained, showing how pH affects hemoglobin's oxygen saturation. Finally, the video covers allosteric modulation, differentiating between positive and negative modulators.

What is the main characteristic of positive cooperativity in proteins like hemoglobin?

• Binding of the first ligand has no effect on subsequent binding.

• Binding of the first ligand prevents any further binding.

• Binding of the first ligand makes subsequent binding more favorable.

• Binding of the first ligand makes subsequent binding less favorable.

Which structural component of hemoglobin is crucial for its ability to bind oxygen?

• Disulfide bridge

• Alpha helix

• Beta sheet

• Porphyrin ring

What does a sigmoidal saturation curve indicate about hemoglobin's binding properties?

• It exhibits cooperative binding.

• It does not bind oxygen at all.

• It binds oxygen independently.

• It binds oxygen in a linear fashion.

How does a decrease in pH affect hemoglobin's oxygen binding according to the Bohr effect?

• Decreases oxygen binding

• Increases oxygen binding

• Completely stops oxygen binding

• Has no effect on oxygen binding

What is the relationship between pH and hemoglobin's state in the context of the Bohr effect?

• Lower pH favors the R state

• pH has no effect on hemoglobin's state

• Higher pH favors the T state

• Lower pH favors the T state

What happens to hemoglobin's oxygen binding as the pH increases?

• Oxygen binding decreases

• Oxygen binding remains constant

• Oxygen binding increases

• Oxygen binding stops completely

What is an allosteric modulator?

• A molecule that binds to a protein without changing its conformation

• A molecule that binds to a protein and changes its conformation

• A molecule that enhances the protein's enzymatic activity

• A molecule that prevents any binding to a protein

Which type of allosteric modulator is oxygen in the context of hemoglobin?

• Positive homotropic modulator

• Negative homotropic modulator

• Positive heterotropic modulator

• Negative heterotropic modulator

What distinguishes a homotropic allosteric modulator from a heterotropic one?

• Heterotropic modulators do not affect binding.

• Homotropic modulators are the same as the ligand.

• Heterotropic modulators are the same as the ligand.

• Homotropic modulators are different from the ligand.

What is the effect of positive allosteric modulation on a protein's binding affinity?

• Decreases binding affinity

• Completely inhibits binding

• Increases binding affinity

• Has no effect on binding affinity