Nutrition Basics - Chapter 6: Proteins

Vocabulary flashcards covering the definitions, structures, types, synthesis, digestion processes, and nutritional aspects of proteins as described in Chapter 6.

Proteins

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

Amino Acids

Simple monomers composed of the elements 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.

Essential Amino Acids

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

Nonessential Amino Acids

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

Conditionally Essential Amino Acids

Amino acids that become essential during certain times in life, such as child growth (e.g., Arginine, Cysteine, Glutamine).

Transcription

The process of copying DNA into messenger RNA during protein synthesis.

Translation

The process of decoding messenger RNA and synthesizing a protein.

Protein Folding

The step in protein synthesis where a sequence of amino acids transforms into its dictated shape.

Peptide Bonds

Chemical bonds that connect amino acids to build protein chains.

Primary Structure

The first level of protein organization consisting of a sequence of amino acids in a polypeptide chain.

Denaturation

Physical changes that take place in a protein’s structure when exposed to external stress (e.g., heat, acid, salt, alcohol), causing the folded structure to unravel.

Pepsin

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

Chymotrypsin and Trypsin

Two major pancreatic enzymes released into the small intestine to further break down protein fragments.

Protein Turnover

The process of continually breaking down proteins and building new ones, involving about $250\,g$ of protein daily.

Collagen

A strong, fibrous protein made up mostly of glycine and proline that comprises 30 percent of bone tissue and makes them strong but flexible.

Enzymes

Proteins that catalyze specific chemical reactions by lowering the amount of 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 are made from proteins.

Albumin

The most abundant protein in blood which plays a role in fluid balance, acid-base balance, and the transport of biological molecules.

Lysozyme

An enzyme that destroys bacteria as part of the immune system's protection function.

Antibodies

Proteins produced by the immune system 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, poor skin health, and growth retardation.

Marasmus

A syndrome of severe protein and energy deficiency characterized by emaciation, poor skin health, and growth retardation.

Nitrogen Balance

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

Complete Protein Sources

Foods that contain all nine of the essential amino acids in the proportions needed by the human body (e.g., milk, eggs, soy).

Incomplete Protein Sources

Foods that contain some, but not all, of the essential amino acids (e.g., most plant-based proteins).

Complementary Foods

A combination of foods that when consumed together contain all nine essential amino acids at adequate levels (e.g., hummus and whole-wheat pita).

PDCAAS

Protein Digestibility Corrected Amino Acid Score; a formula used by the FDA to determine food's protein quality based on amino acid content and human digestibility.

Sarcopenia

The age-related decline in muscle mass and strength.

Protein RDA Equation

The mathematical formula to calculate daily protein requirement: $(Weight\,in\,lbs. \div 2.2\,kg/lb) \times 0.8\,g/kg$.