Nutrition Chapter 6

What are proteins composed of?

Proteins are composed of carbon, hydrogen, oxygen, and nitrogen.

What are amino acids?

Building blocks of proteins, each containing an amino group, an acid group, and a unique side chain

What is the difference between essential and nonessential amino acids?

Essential amino acids must be obtained from the diet, while nonessential amino acids can be synthesized by the body.

What are the four levels of protein structure?

Primary, secondary, tertiary, and quaternary structures.

What is a peptide bond?

A bond that links amino acids together in a protein chain.

Where does protein digestion begin?

In the stomach, with the enzyme pepsin breaking down polypeptides.

How are amino acids absorbed in the body?

They are transported by specific carriers to intestinal cells and then to the liver if not immediately used.

What are transcription and translation?

Transcription is the process where DNA codes for mRNA; translation is when mRNA directs protein synthesis.

What causes protein denaturation?

Heat, acid, or other conditions disrupt protein structure, rendering it nonfunctional.

What are the three states of nitrogen balance?

Positive (growth), equilibrium (maintenance), and negative (starvation/illness)

What determines protein quality?

Digestibility and amino acid composition.

What is the difference between high-quality and low-quality proteins?

High-quality proteins contain all essential amino acids; low-quality proteins lack one or more essential amino acids

What are complementary proteins?

Two or more protein sources that together provide all essential amino acids (e.g., beans and rice).

What are major functions of proteins in the body?

Structural support, enzymes, hormones, fluid balance, acid-base regulation, transport, immunity, energy source.

What are risks of excess protein intake?

Kidney strain, bone loss, heart disease risk from animal proteins.

What is the RDA for protein?

0.8 g/kg of body weight per day.

What are effects of protein deficiency?

Muscle loss, weakened immunity, fluid imbalance (edema).

What happens to excess amino acids?

They are deaminated, converted to glucose or fat, and excreted as urea.

How is excess nitrogen excreted from the body?

As urea, via the kidneys.

What are good dietary sources of protein?

Meat, fish, eggs, dairy, legumes, nuts, and seeds.