KINE 112 – Proteins Study Guide Flashcards

A vocabulary-based flashcard set covering the chemical structure, organization, synthesis, functions, digestion, and balance of proteins based on KINE 112 lecture materials.

Amino group

A functional group (represented as $NH_2$) found in every amino acid.

Acid group

A functional group (represented as $COOH$) found in every amino acid.

Side chain ($R$ group)

The only part of an amino acid that differs between types and determines their specific characteristics.

Dipeptide

A chain consisting of 2 amino acids linked together.

Tripeptide

A chain consisting of 3 amino acids linked together.

Polypeptide

A protein fragment containing more than 10 amino acids.

Primary Structure

The specific sequence of amino acids in a linear chain.

Secondary Structure

The bends and folds in a protein chain caused by chemical bonds.

Tertiary Structure

The three-dimensional shape of a protein which determines its physiological function.

Quaternary Structure

The interaction of two or more proteins which can activate or deactivate function.

Essential Amino Acids

A group of 9 amino acids that the body cannot make and must be obtained from food.

Non-Essential Amino Acids

A group of 11 amino acids that the body can synthesize from other amino acids.

Transamination

The process through which the body synthesizes non-essential amino acids from other amino acids.

Limiting Amino Acid

The essential amino acid in shortest supply that, when missing, causes protein synthesis to slow or stop.

Protein Turnover

The constant process of proteins being broken down, repaired, and rebuilt.

Edema

Swelling caused by fluid accumulation, which can occur when plasma protein levels are low.

Buffers

Proteins that help maintain normal body pH by absorbing or releasing hydrogen ions.

Hemoglobin

A transport protein responsible for carrying oxygen in the blood.

Transferrin

A transport protein responsible for carrying iron in the blood.

Lipoproteins

Proteins characterized by their function of transporting lipids.

Gluconeogenesis

The process by which the liver converts amino acids into glucose when carbohydrate intake is low.

Protein Energy Density

Proteins provide $4\,kcal/g$ of energy.

Complete Proteins

Food sources that contain all 9 essential amino acids, such as meat, eggs, dairy, tofu, and quinoa.

Incomplete Proteins

Food sources low in one or more essential amino acids, such as rice, beans, lentils, nuts, and seeds.

Complementary Proteins

Two incomplete proteins combined (e.g., rice + beans) to provide a complete set of essential amino acids.

Denaturation

The process where heat (cooking) or acid ($HCl$ in the stomach) uncoils or softens proteins to make them easier to digest.

Pepsin

A stomach enzyme activated by gastrin that is responsible for about $10-20\%$ of protein digestion.

Pancreatic Enzymes

Specific enzymes including trypsin, chymotrypsin, and carboxypeptidase that break proteins into peptides and amino acids in the small intestine.

Nitrogen Equilibrium

A state where nitrogen intake equals nitrogen output, typical in healthy adults.

Positive Nitrogen Balance

A state where nitrogen intake is greater than output (Nitrogen In > Nitrogen Out), occurring during growth, pregnancy, or recovery.

Negative Nitrogen Balance

A state where nitrogen output is greater than intake (Nitrogen In < Nitrogen Out), occurring during fasting, protein deficiency, or infection.

Adult Protein RDA

The recommended intake for healthy adults is $0.8\,g/kg/day$.

Anaphylaxis

A severe, emergency allergic reaction causing airway swelling, drop in blood pressure, and difficulty breathing.