Metabolism and Enzyme Regulation: Principles and Pathways in Biochemistry

What does metabolism encompass?

All biochemical reactions occurring within a living organism.

What are the two primary classes of metabolic pathways?

Catabolic pathways and anabolic pathways.

What is the function of catabolic pathways?

They break down molecules to release energy or produce smaller building blocks.

What is the function of anabolic pathways?

They build up molecules, requiring energy input.

What is the ultimate goal of metabolic pathways?

To produce a chemical that contributes to cellular synthesis or breaks down substances from consumed food.

What does the first law of thermodynamics state?

Energy cannot be created or destroyed; it can only change forms.

What is the principle of conservation of energy in metabolism?

It implies that all energy entering and leaving a system can be tracked.

What does the second law of thermodynamics address?

Entropy, stating that the entropy of the universe is always increasing.

How does the human body relate to entropy?

It is a highly organized system that exhibits negative entropy but releases heat and small molecules, increasing disorder in its surroundings.

What is free energy represented as in metabolic reactions?

Delta G (ΔG).

What does a negative ΔG indicate?

A spontaneous or exergonic reaction where energy is released.

What does a positive ΔG indicate?

An unfavorable or endergonic reaction that requires energy input.

What is the Gibbs equation used for?

To relate ΔG to the entropy change, temperature, and enthalpy change of a reaction.

What is ATP and its role in metabolism?

Adenosine triphosphate, the primary energy currency in biological systems.

How much energy is released when ATP is hydrolyzed?

Approximately 7.3 kilocalories per mole.

What is the role of enzymes in metabolic reactions?

They catalyze reactions, speeding them up without being consumed.

How do enzymes lower the activation energy (EA) required for reactions?

By facilitating the transition state and reducing the energy barrier.

What is the induced fit model in enzyme activity?

A conformational change in the enzyme that enhances its ability to catalyze the reaction.

What environmental factors influence enzyme activity?

Temperature and pH.

At what temperature do human enzymes operate best?

37 degrees Celsius.

What is an example of an anabolic pathway?

The synthesis of proteins from amino acids.

What is an example of a reaction that can be driven by ATP hydrolysis?

The synthesis of glutamine from glutamic acid and ammonia.

What happens to the overall entropy of the universe according to the second law of thermodynamics?

It must always increase, even if individual reactions exhibit negative entropy.

What role do enzymes play in metabolic processes?

Enzymes are crucial for enabling reactions to occur at rates necessary for life.

How do enzymes facilitate biochemical reactions?

They lower activation energy and adapt to environmental conditions.

What is the interaction between enzymes and substrates?

Enzymes interact with substrates by breaking non-covalent interactions to facilitate their release.

What environmental factors can affect enzyme activity?

Temperature, pH, salt concentration, and pressure.

Give an example of enzyme adaptation based on temperature.

Human enzymes function best at around 37 degrees Celsius, while bacterial enzymes from hot springs operate optimally at much higher temperatures.

What is the significance of amino acid sequence changes in enzymes?

Modifications to a few amino acids can enhance enzyme function in different environments due to evolutionary pressures.

How does pH affect enzyme activity? Provide an example.

Pepsin operates optimally at a pH of around 2, while trypsin functions best at a pH of about 8.

What are homologous enzymes?

Enzymes from different organisms that catalyze the same reaction but have different amino acid sequences.

What are cofactors in enzymatic reactions?

Non-protein molecules that assist in enzyme activity, which can be inorganic (like metal ions) or organic (like coenzymes).

What is competitive inhibition?

A type of inhibition where inhibitors bind directly to the enzyme's active site, preventing substrate binding.

What is non-competitive inhibition?

Inhibitors bind elsewhere on the enzyme, altering its shape and reducing its activity.

How can natural inhibitors affect enzymatic reactions?

They modulate reactions to prevent them from occurring too rapidly.

What are the mechanisms of enzyme regulation?

Gene regulation, allosteric regulation, and feedback regulation.

What is allosteric regulation?

Affects enzyme activity through molecules binding to sites other than the active site, which can enhance or inhibit activity.

What is cooperativity in enzyme regulation?

When a substrate binds to one active site of a multi-subunit enzyme, enhancing the activity of other active sites.

Provide an example of cooperativity.

Hemoglobin, where oxygen binding to one subunit increases the likelihood of binding to remaining subunits.

What is feedback regulation in metabolic pathways?

A process where the end product of a pathway inhibits an enzyme involved in its production.

How does compartmentalization regulate enzyme activity?

By confining enzymes to specific cellular locations, controlling their activity based on substrate availability.

Why is the regulation of enzyme activity important?

It maintains metabolic balance and prevents detrimental effects from unregulated enzymatic reactions.