Question

1. what is activation energy (eₐ)? the initial energy needed to start a chemical reaction.
2. what effect does an enzyme have on eₐ?
3. how is δg affected by the enzyme?
4. explain how protein structure is involved in enzyme specificity.
5. explain how some factors affect enzyme’s activity.
6. compare and contrast competitive inhibitors and noncompetitive inhibitors.

concept 8.5 regulation of enzyme activity helps control metabolism

1. explain how feedback inhibition works.

Explanation:

1. An enzyme lowers the activation energy ($E_A$). It provides an alternative reaction pathway with a lower energy - barrier, facilitating the reaction to occur more readily.
2. The change in free - energy ($\Delta G$) is unaffected by the enzyme. $\Delta G$ is determined by the free - energy of the reactants and products and is a state function, not influenced by the reaction pathway.
3. The specific three - dimensional structure of a protein (enzyme) determines its active site. The active site has a unique shape and chemical properties that allow it to bind specifically to a particular substrate, thus contributing to enzyme specificity.
4. Factors such as temperature, pH, substrate concentration, and the presence of cofactors or inhibitors can affect enzyme activity. Temperature and pH can alter the enzyme's structure, substrate concentration can affect the rate of binding, and cofactors are necessary for some enzymes to function while inhibitors can slow or stop enzyme activity.
5. Competitive inhibitors bind to the active site of an enzyme, competing with the substrate for binding. Non - competitive inhibitors bind to a site other than the active site (allosteric site), causing a conformational change in the enzyme that reduces its activity.
6. Feedback inhibition occurs when the end - product of a metabolic pathway acts as an inhibitor of an earlier enzyme in the pathway. As the concentration of the end - product increases, it binds to the allosteric site of the enzyme, reducing the enzyme's activity and thus slowing down the entire metabolic pathway.

Answer:

1. An enzyme lowers $E_A$.
2. $\Delta G$ is unaffected by the enzyme.
3. The protein's 3 - D structure determines the active - site for substrate binding, contributing to specificity.
4. Temperature, pH, substrate concentration, cofactors, and inhibitors affect enzyme activity.
5. Competitive inhibitors bind to the active site; non - competitive inhibitors bind to an allosteric site.
6. The end - product of a pathway inhibits an earlier enzyme in the pathway.