Where does protein digestion begin and end in the human body?

Determine the product of protein digestion.

Which of the following statement/s is/are true?

I. Nitrogen from amino acids is directly converted into ammonia and stored in the body.

II. Amino acids can be converted into intermediates of the citric acid cycle for energy production.

III. The amino group from amino acids is converted to urea in the liver and excreted in the urine.

IV. Amino acids are primarily catabolized in muscle tissue, where they are stored for later use.

Ketone bodies, acetyl-CoA, and glucose are three metabolites that result from the breakdown of the carbon skeleton of amino acids. Determine which of these metabolites are produced by ketogenic amino acids and which by glucogenic amino acids.

What is/are the metabolic product/s generated from the carbon atoms of phenylalanine during its catabolism?

Is the statement true or false? If false, modify the underlined word.

The metabolic substrate that can be produced directly from the carbon atoms of the amino acid cysteine is oxaloacetate.

Which of the following statements about the urea cycle is/are true?

I. Ammonia is directly excreted by the liver into the bloodstream for removal from the body.

II. Ammonia produced from amino acid catabolism is detoxified in the liver via the urea cycle, where it is converted into urea for safe excretion.

III. Urea is synthesized in the kidneys as part of the urea cycle and then excreted in the urine.

IV. NH₄⁺ is primarily converted into urea by the liver and excreted through the urea cycle.

In the liver, the relative activity of ornithine transcarbamylase and arginase is lower than that of argininosuccinate synthetase. Is this statement true or false?

In step 2 of the urea cycle, it appears that one ATP is hydrolyzed, but the actual cost is actually two ATP. Why is this true?

Which of the following definitions and explanations regarding essential and non-essential nutrients is incorrect?

Determine how many ATPs you would make if you consumed a tetrapeptide comprised of methionine, proline, leucine, and asparagine. (Assume 1 NADH = 3 ATP, 1 FADH₂ = 2 ATP. Don’t include ATP produced/consumed from α-keto acid transformations before entering the citric acid cycle.)

Which of the following biochemical reactions occur in anabolic pathways?

(i) Condensation

(ii) Hydrolysis

(iii) Reduction

(iv) Carboxylation