Mcb 2000 Exam 2

Crystallography is the scientific study of crystals and their structure using diffraction techniques to determine the arrangement of atoms within a crystal lattice. It is commonly used in chemistry, material science, and biology.

Hemoglobin and Myoglobin share evolutionary relatedness and sequence homology, and both contain the heme prosthetic group, which allows them to bind oxygen. They have similar functions related to oxygen binding despite being present in different tissues or cells.

A prosthetic group is a non-protein molecule that is permanently attached to a protein and helps in its function. It is not a type of organic molecule for protein folding, a chain of amino acids, or an enzyme for carbohydrate breakdown.

Myoglobin is a protein found in muscle tissue that is responsible for storing oxygen. It consists of a single polypeptide chain and is a monomer, with similar numbers of amino acids in sequence. The incorrect answers provide misleading information about the function, structure, and composition of Myoglobin.

Hemoglobin plays a crucial role in transporting essential gases like oxygen, carbon dioxide, and hydrogen ions in the body. It also helps maintain pH balance and functions as a tetramer structure consisting of specific alpha and beta subunits for efficient gas exchange.

Heme binds oxygen due to the poor solubility of oxygen in water, the strong tendency of transition metals to bind oxygen, and the necessity to sequester iron to render it less reactive.

Heme is characterized by its protoporphyrin ring, hydrophobic and planar nature, as well as the role of nitrogens in preventing Fe2+ to Fe3+ conversion. It is also sequestered within the protein's structure, making it an essential structural feature.

Hemoglobin's main function is to bind oxygen in the lungs and release it in the capillaries for efficient oxygen transport.

Proteins with allosteric behavior have distinct characteristics such as quaternary structure, cooperativity leading to a change in function, and sigmoidal binding curves. Primary structure alone is not sufficient to explain allosteric regulation, non-covalent interactions are crucial in allosteric mechanisms, and binding curves for allosteric proteins are not linear but rather sigmoidal in shape.

The confirmation of hemoglobin in its less active state, which promotes the release of oxygen, is known as 'taught'. This confirmation has low affinity for oxygen and helps in the release of oxygen from hemoglobin molecules.

2,3 BPG plays a crucial role in modulating the oxygen-binding affinity of hemoglobin by stabilizing the T-state conformation. This results in enhanced oxygen release to tissues. The other options are not correct as 2,3 BPG does not impact blood pressure, rather it affects oxygen binding; it is produced during glycolysis and facilitates oxygen release, rather than inhibiting glycolysis; and it decreases, not enhances, oxygen binding affinity to hemoglobin.

The correct answer highlights that a more acidic environment favoring the T state, along with the collaboration of H+ and CO2 to promote O2 release, are crucial factors influencing the binding of O2 to Hb.

The Bohr Effect refers to the phenomenon where protons react with Histamine side chains, particularly His-146 in the beta subunit of hemoglobin. This protonation promotes the release of oxygen from hemoglobin, allowing it to be delivered to tissues in need.

The correct chemistry of CO2 binding involves specific conditions like low pH and high CO2 levels in peripheral tissues, along with the binding to alpha amino groups and formation of salt bridges.

Enzymes are biological catalysts that speed up reactions by lowering the activation energy, affecting the rate at which a reaction occurs but not the overall direction of the reaction.

The first law of thermodynamics states that the total energy of a system is conserved, which means energy cannot be created or destroyed, only transformed. This includes the internal energy, heat absorbed, and work done on the system.

The Second law of thermodynamics explains that systems tend towards disorder and randomness, with all processes moving towards equilibrium where potential energy is minimized. It also states that total equilibrium does not allow energy to be captured for work, with biological systems working against this tendency.

The major energy requiring reactions in the body include protein synthesis, maintaining the concentration of sodium ions (Na+), and freeing energy in glycolysis. ATP hydrolysis in muscle contraction, DNA replication in cell division, and fatty acid synthesis in adipose tissue do not specifically represent major energy requiring reactions in the body.

A favorable reaction is one that releases energy and increases entropy, leading to a negative Gibbs free energy value. This contrasts with unfavorable reactions that require energy input and decrease entropy. The key distinction lies in whether the reaction leads to an increase or decrease in entropy and the energy release or absorption.

Gibbs free energy is a measure of the energy change as a system moves from its initial state to equilibrium. It refers to the available energy to do work and depends on factors such as the chemical reaction itself, the system's distance from equilibrium, and the quantities of reactants and products involved.

Free energy for a reaction is defined by the equation *delta G = delta H - T delta S, which takes into account the enthalpy, entropy, and temperature at constant pressure. It is not simply the total energy available or released during a reaction, and it is affected by the factors of temperature and entropy.

The equilibrium constant, Keq, is a measure of the tendency of a reaction to go toward completion. A large Keq indicates that the reaction will proceed until the conversion of reactants to products is almost complete. This constant is not a representation of the reaction rate, initial concentrations of reactants, or unaffected by changes in temperature.

The correct equation for calculating free energy change under standard states involves various terms dependent on the substances involved in the reaction and their concentrations or pressures. This equation is derived from thermodynamics principles and is crucial in determining the spontaneity of reactions.

When a reaction is at equilibrium, the change in Gibbs free energy (dG) is equal to zero. By determining the concentration of reactants and products at equilibrium, we can calculate the equilibrium constant (Keq), which in turn helps us understand the change in free energy during the conversion of reactants to products.

In biochem reactions, the standard state for [H+] is not 1M or 10^-14M. The pH in most cells is near the neutral range, and the modified standard state is denoted as Go'.

The correct answer provides a comprehensive explanation of what Go' indicates in relation to chemical reactions and cellular energetics.

The standard free energy change (ΔG°) can be used to predict the direction of a chemical reaction based on whether the value is negative, zero, or positive. A negative value indicates that the reaction will proceed forward, a zero value indicates that the reaction is at equilibrium, and a positive value indicates that the reaction will proceed in reverse.

The breakdown of ATP is a favorable process due to the release of energy and increase in entropy, making it thermodynamically favorable.