Chpt 5 BCHM 1/2 MC only

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Which type of protein function involves altering the chemical configuration or composition of a bound molecule?

Protein interacting dynamically

Protein changing its conformation

Protein acting as a reaction catalyst (correct)

Protein binding with other molecules

Which of the following is true about ligands?

Ligands are proteins that bind to other molecules

Ligands are molecules that change the conformation of proteins

Ligands are proteins that catalyze reactions

Ligands are molecules that bind reversibly to proteins (correct)

Protein-ligand interactions are specific because...

Proteins have separate binding sites for different ligands (correct)

Proteins can bind to any type of molecule

Proteins can bind to thousands of different ligands

Proteins can only bind to one type of ligand

What is the role of conformational changes in proteins?

Conformational changes maintain the high degree of order in a living system (D) Signup and view all the answers

How do proteins interact with ligands?

Proteins interact with ligands through reversible binding (C) Signup and view all the answers

What is the significance of protein-ligand interactions in maintaining order in a living system?

Protein-ligand interactions allow for specific molecular interactions (A) Signup and view all the answers

What is the range of conformational changes in proteins?

Conformational changes in proteins can be subtle or dramatic (A) Signup and view all the answers

Which of the following best describes the principle of induced fit?

The binding of a protein and a ligand leads to a conformational change in the protein (C) Signup and view all the answers

Which of the following is true about multisubunit proteins?

A conformational change in one subunit can affect the conformation of other subunits (C) Signup and view all the answers

What is the term used to describe the reversible binding of other molecules by a protein?

Ligand (B) Signup and view all the answers

What are the coordination bonds of iron in a heme prosthetic group?

Four to nitrogen atoms in the flat porphyrin ring and two perpendicular to the porphyrin (C) Signup and view all the answers

What is the role of myoglobin in the body?

Facilitates O2 diffusion in muscle tissue (A) Signup and view all the answers

How can protein-ligand interactions be described quantitatively?

By a simple equilibrium expression (A) Signup and view all the answers

What does the association constant (Ka) measure?

The affinity of the ligand for the protein (B) Signup and view all the answers

Which state of hemoglobin has a higher affinity for oxygen?

R state (C) Signup and view all the answers

What triggers a conformational change from the T state to the R state in hemoglobin?

Binding of oxygen (B) Signup and view all the answers

What type of binding curve does hemoglobin exhibit for oxygen?

Sigmoidal (C) Signup and view all the answers

What is the purpose of hemoglobin binding oxygen cooperatively?

To bind oxygen efficiently in the tissues (B) Signup and view all the answers

What is the Hill coefficient in the Hill equation used for?

To measure the cooperativity of binding (D) Signup and view all the answers

What does a Hill coefficient greater than 1 indicate in a Hill plot?

Positive cooperativity (A) Signup and view all the answers

What type of modulator is carbon monoxide for hemoglobin?

Inhibitor (B) Signup and view all the answers

What is the purpose of ion pairs in stabilizing the T state of hemoglobin?

To enhance oxygen binding (C) Signup and view all the answers

What is the effect of oxygen binding on the conformation of hemoglobin?

All of the above (D) Signup and view all the answers

Which of the following correctly defines the dissociation constant (Kd)?

The reciprocal of the equilibrium constant for the release of ligand (D) Signup and view all the answers

Which of the following statements about the binding affinity of a ligand is true?

Lower Kd indicates higher affinity (B) Signup and view all the answers

What is the value of Kd when 50% of the ligand-binding sites are occupied?

Kd/2 (C) Signup and view all the answers

Which of the following correctly describes the effect of protein structure on ligand binding?

Protein structure affects the binding affinity of ligands (B) Signup and view all the answers

What is the primary reason for carbon monoxide (CO) binding more strongly to free heme than oxygen (O2)?

Differences in the orbital structures (A) Signup and view all the answers

What is the role of the distal histidine (His) in myoglobin?

It stabilizes the Fe-O2 polar complex (C) Signup and view all the answers

Which of the following best describes the quaternary structure of hemoglobin?

Strong interactions between unlike subunits (B) Signup and view all the answers

Which of the following statements is true about the dissociation constant (Kd)?

Kd is the ligand concentration at which half of the receptor binding sites are occupied (B) Signup and view all the answers

What is the relationship between Kd and affinity?

Higher Kd indicates lower affinity (A) Signup and view all the answers

What is the role of Myoglobin's distal His in increasing heme's affinity for O2?

It stabilizes the Fe-O2 polar complex (D) Signup and view all the answers

What is the main function of erythrocytes (red blood cells)?

To transport O2 (B) Signup and view all the answers

How many subunits does adult hemoglobin have?

4 (A) Signup and view all the answers

What type of interaction is responsible for the quaternary structure of hemoglobin?

Salt bridges (B) Signup and view all the answers

What is the term for the structural adaptation that occurs between a protein and a ligand?

Induced fit (D) Signup and view all the answers