Macronutrient & Micronutrient Science Flashcards

What defines a 'conditionally essential' amino acid in human nutrition?

Answer: An amino acid that becomes essential during illness, growth, or high physiological stress when endogenous synthesis is insufficient

Conditionally essential amino acids (e.g., glutamine, arginine) are normally synthesized adequately but become dietary requirements during stress, illness, or rapid growth.

Which B vitamin is required for the methylation cycle and its deficiency leads to elevated homocysteine levels?

Answer: Folate (B9) and cobalamin (B12)

Both folate and B12 are essential cofactors for remethylating homocysteine to methionine; deficiency of either causes hyperhomocysteinemia.

In lipid biochemistry, what distinguishes a phospholipid from a triglyceride?

Answer: Phospholipids replace one fatty acid with a phosphate-head group, making them amphipathic

Phospholipids have a glycerol backbone with two fatty acids and a phosphate-containing head group, giving them both hydrophilic and hydrophobic regions critical for membrane structure.

Which micronutrient deficiency is most associated with impaired wound healing and taste/smell dysfunction?

Answer: Zinc

Zinc is essential for metalloenzymes involved in collagen synthesis, immune function, and taste receptor maintenance; deficiency impairs wound healing and causes hypogeusia.

What is the significance of the omega-6 to omega-3 ratio in the diet according to nutritional therapy principles?

Answer: An excessively high omega-6 to omega-3 ratio promotes inflammatory eicosanoid production

Arachidonic acid (omega-6) and EPA (omega-3) compete for the same enzymes; a high omega-6:omega-3 ratio shifts eicosanoid synthesis toward pro-inflammatory series-2 prostaglandins.

Which process describes the conversion of excess amino acids to glucose in the liver during prolonged fasting?

Answer: Gluconeogenesis

Gluconeogenesis uses glucogenic amino acid carbon skeletons (after transamination removes the nitrogen) to synthesize new glucose in the liver and kidneys.

Iodine is an essential component of which hormones, and what gland synthesizes them?

Answer: Thyroxine (T4) and triiodothyronine (T3), synthesized by the thyroid gland

Iodine is incorporated into the thyroid hormones T4 (four iodine atoms) and T3 (three iodine atoms) by the thyroid gland.