Nutrition Basics: Chapter 6 - Proteins

This flashcard set covers the fundamental concepts of protein structure, categories of amino acids, protein synthesis, digestion, bodily functions, and related health conditions based on Chapter 6.

Proteins

Macromolecules composed of monomeric subunits called amino acids, making up approximately $20\%$ of the human body.

Amino acids

Simple monomers composed of carbon, oxygen, hydrogen, and nitrogen that serve as the building blocks of protein.

Nonpolar amino acids

Hydrophobic amino acids with side groups that are long or bulky.

Polar amino acids

Hydrophilic amino acids that are not charged.

Acidic amino acids

Hydrophilic amino acids that are negatively charged.

Basic amino acids

Hydrophilic amino acids that are positively charged.

Nonessential amino acids

Amino acids that are made in the human body in sufficient amounts to meet metabolic needs.

Essential amino acids

Amino acids that are not made by the human body and must be obtained through the diet.

Conditionally essential amino acids

Amino acids that become essential during specific life stages, such as periods of child growth.

Transcription

The first step of protein building, involving the process of copying DNA into messenger RNA (mRNA).

Translation

The second step of protein building, involving the decoding of messenger RNA to synthesize a protein.

Protein folding

The final step of protein building where a sequence of amino acids transforms into its dictated three-dimensional shape.

Peptide bond

The chemical bond that connects amino acids together to build protein chains.

Primary structure

The first level of protein organization, consisting of the specific sequence of amino acids.

Secondary structure

The second level of protein organization, characterized by patterns such as the alpha helix and beta sheet.

Tertiary structure

The third level of protein organization, where the protein peptide folds into a unique three-dimensional shape.

Quaternary structure

The fourth level of protein organization, formed when multiple protein strands twist together or overlap.

Denaturation

Physical changes in a protein's structure caused by external stress (like heat, acid, or salt), causing it to unravel into a long strand of amino acids.

Pepsin

An enzyme secreted by the stomach lining that initiates the breakdown of protein chains into smaller fragments.

Protein turnover

The continuous biological process of breaking down proteins and building new ones, involving over $250\,g$ of protein daily.

Collagen

A strong, fibrous protein made mostly of glycine and proline that makes up $30\%$ of bone tissue and is found in tendons, ligaments, and skin.

Enzymes

Proteins that catalyze specific chemical reactions by lowering the energy and time required for the reaction without being consumed.

Hormones

Chemical messengers produced by endocrine glands that can turn enzymes on and off; many, though not all, are synthesized from proteins.

Albumin

The most abundant protein in the blood, responsible for fluid balance, acid-base balance, and the transport of biological molecules.

Lysozyme

An enzyme that functions as part of the immune system by destroying bacteria.

Antibodies

Proteins that protect the body against unwanted intruders, such as the SARS-CoV-2 virus.

Kwashiorkor

A syndrome of severe protein and micronutrient deficiency characterized by swelling of the feet and abdomen, low muscle mass, and liver malfunction.

Marasmus

A syndrome of severe protein and energy deficiency characterized by emaciation and growth retardation.

Nitrogen balance

A state where the amount of protein input into the body equals the amount used up and excreted.

Complete protein sources

Foods, mostly animal-based (except soy), that contain all nine essential amino acids in the proportions needed by the body.

Incomplete protein sources

Foods that contain some, but not all, of the essential amino acids.

Complementary foods

A combination of foods that, when consumed together, provide all nine essential amino acids at adequate levels (e.g., beans and rice).

PDCAAS (Protein Digestibility Corrected Amino Acid Score)

The formula-based method adopted by the FDA to determine protein quality by evaluating amino acid content and human digestibility.

Sarcopenia

The age-related decline in muscle mass and strength, which may be mitigated by adequate dietary protein.