Metabolism, Enzymes, and Protein Structure

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Questions and Answers

During prolonged starvation, the liver produces ketone bodies from acetyl-CoA. What is the primary purpose of this process?

To eliminate excess nitrogen from the breakdown of proteins.
To synthesize glucose for the brain.
To provide an alternative fuel source for the brain and other tissues. (correct)
To store excess acetyl-CoA as fat.

Which statement accurately describes the role and characteristics of enzymes?

Enzymes are consumed during reactions and permanently alter the products.
Enzymes increase the activation energy of a reaction, thus slowing it down.
Enzymes are inorganic catalysts that function best at high temperatures.
Enzymes are highly specific for their substrates and are not consumed in the reaction. (correct)

Which level of protein structure is characterized by the overall three-dimensional arrangement of all atoms in a single polypeptide chain and is stabilized by hydrophobic interactions, hydrogen bonds, and disulfide bonds?

Quaternary structure
Secondary structure
Tertiary structure (correct)
Primary structure

What is the fundamental difference between DNA and RNA in terms of their structure and function?

DNA is typically double-stranded and contains thymine, storing genetic information, while RNA is typically single-stranded, contains uracil, and plays a role in protein synthesis. (C) Signup and view all the answers

In a metabolic pathway, feedback inhibition is a common regulatory mechanism. How does it work?

The product of the pathway inhibits an earlier step in the pathway. (A) Signup and view all the answers

Which of the following best describes the role of chaperone proteins in protein folding?

They assist in the proper folding of proteins and prevent aggregation. (D) Signup and view all the answers

How do competitive and noncompetitive inhibitors differ in their mechanisms of action on enzymes?

Competitive inhibitors bind to the active site, blocking substrate binding, while noncompetitive inhibitors bind to a different site, altering enzyme conformation. (D) Signup and view all the answers

What is the significance of the Recommended Dietary Allowance (RDA) for nutrients?

It is the average daily level of intake sufficient to meet the nutrient requirements of nearly all healthy individuals. (B) Signup and view all the answers

Which of the following coenzymes is commonly derived from vitamins and carries chemical groups during enzymatic reactions?

NAD+ (B) Signup and view all the answers

During fatty acid synthesis, two-carbon units are sequentially added to a growing fatty acid chain. Where does this process primarily occur within the cell?

Cytoplasm (C) Signup and view all the answers

Flashcards

Metabolic Pathways

A series of interconnected biochemical reactions converting a starting molecule into a product through intermediates.

Catabolic Pathways

Pathways that break down complex molecules into simpler ones, releasing energy.