Nutrition: EXSC 225 - Protein and Amino Acids

Vocabulary practice flashcards covering protein chemistry, amino acid classification, digestion, synthesis, functions, and dietary recommendations from EXSC 225.

Proteins (Chemical Composition)

Molecules that contain nitrogen ($N$) atoms in addition to the same atoms found in carbohydrates and lipids: carbon ($C$), hydrogen ($H$), and oxygen ($O$).

Amino Acid (Basic Structure)

A chemical unit consisting of a central carbon ($C$) atom bonded to a hydrogen atom ($H$), an amino group ($NH_2$), an acid group ($COOH$), and a unique side group ($R$ group).

Essential Amino Acids

Nine amino acids that the human body either cannot make at all or cannot make in sufficient quantity to meet its needs, requiring them to be supplied by the diet.

Nonessential Amino Acids

Amino acids that the body can synthesize for itself; more than half of the $20$ common amino acids fall into this category.

Conditionally Essential Amino Acid

A nonessential amino acid that becomes essential when the body cannot synthesize it in adequate amounts under special circumstances, such as when tyrosine becomes essential due to an insufficient supply of phenylalanine.

Dipeptide

A molecule composed of two amino acids bonded together by a condensation reaction.

Tripeptide

A molecule formed by condensation reactions connecting three amino acids together.

Polypeptide

A chain of many amino acids linked together by condensation reactions; most proteins consist of a few dozen to several hundred amino acids.

Insulin

A protein hormone composed of $51$ amino acids across two polypeptide chains, released by the pancreas in response to elevated blood glucose.

Transcription

The first step of protein synthesis in which a stretch of DNA is transcribed to serve as a template for making messenger RNA (mRNA).

Transfer RNA (tRNA)

A type of RNA that collects specific amino acids from the cell fluid and brings them to the mRNA on the ribosome to build the growing protein strand.

Sickle-Cell Hemoglobin

An altered form of hemoglobin resulting from a genetic sequencing error in which valine replaces glutamic acid at the sixth position (Val-His-Leu-Thr-Pro-Val-Glu instead of Val-His-Leu-Thr-Pro-Glu-Glu).

Gene Expression

The process by which a cell synthesizes a specific protein using the instructions coded within its genes, regulated by the cell according to type, amount, and rate needed.

Collagen

A major structural protein matrix laid down by cells to form bones and teeth before being filled with mineral crystals such as calcium, phosphorus, magnesium, and fluoride.

Catabolic Reactions

Chemical reactions facilitated by enzymes that break down substances into smaller components.

Anabolic Reactions

Chemical reactions facilitated by enzymes that build larger substances from smaller units.

Edema

Swelling caused by fluid accumulation in interstitial spaces, occurring when plasma proteins leak out of blood vessels due to inflammation, critical illness, liver disease, or inadequate protein intake.

Buffers

Compounds—such as proteins with negatively charged surfaces—that accept and release hydrogen ions ($H^+$) to maintain the acid-base balance of body fluids.

Normal Blood pH

The tightly controlled acid-base balance of human blood maintained within the narrow range of $7.35$ to $7.45$.

Immunity

A molecular memory developed by the body after producing specific antibodies against an invading antigen, allowing faster antibody production upon future exposures.

Gluconeogenesis

The process in which the body breaks down its tissue proteins to provide amino acids for energy or glucose production during starvation or insufficient carbohydrate intake.

High-Quality Proteins

Dietary proteins that provide adequate quantities of all essential amino acids needed to support the body's functional needs.

Protein Digestibility

A measure of how well a protein is broken down and absorbed, influenced by the food source and companion foods; digestibility is high for most animal proteins and lower for plant proteins.

Adult Protein RDA

The Recommended Dietary Allowance of protein for adults, established at $0.8\,\text{g}$ per kilogram ($0.36\,\text{g}$ per pound) of healthy body weight per day.

Athletic Protein Intake Recommendation

The recommended daily intake of $1.2$ to $2.0\,\text{g}$ of protein per kilogram of body weight, influenced by sport type, training intensity/volume, and recovery goals.

Nutrigenomics

The study of how nutrients and diet influence gene activity.

Nutrigenetics

The study of how genetic variations and genes influence the body's response to and handling of nutrients.

Proline

An imino acid whose amino group has given up a hydrogen atom to form a ring structure with its carbon chain.