BCH 112 Lecture: Homeostasis & Macromolecules

Vocabulary flashcards summarizing fundamental terms and definitions from the BCH 112 lecture on homeostasis and the structure / function of macromolecules.

Homeostasis

The body’s effort to maintain a stable, balanced internal environment despite changing conditions.

Homeostatic Regulation

The continuous process of monitoring and adjusting physiological systems to preserve homeostasis.

Receptor (Homeostasis)

Sensor that detects a change in the environment and sends information to the control center.

Control Center

Integration site that processes information from receptors and issues commands.

Effector

Organ or tissue that carries out commands from the control center, opposing or enhancing the stimulus.

Negative Feedback

A response that reverses a change in a variable, promoting stability and homeostasis (e.g., CO₂ regulation).

Positive Feedback

A response that amplifies a change in a variable, often destabilizing (e.g., blood clotting, childbirth).

Harmful Positive Feedback

Runaway positive feedback that endangers the body, such as a dangerously escalating fever.

Thermoregulation

Negative-feedback control of body temperature via skin receptors, hypothalamus, and sweat/blood-vessel effectors.

Polymer

A long molecule made of many similar or identical monomers linked by covalent bonds.

Monomer

A small molecule that is a building block of polymers.

Dehydration (Condensation) Reaction

Polymer-forming reaction that joins monomers by removing a water molecule.

Hydrolysis

Reaction that breaks polymer bonds by adding water, releasing monomers.

Carbohydrate

Macromolecule class that includes sugars and their polymers.

Monosaccharide

Simplest carbohydrate (simple sugar) with formula CₙH₂ₙOₙ; e.g., glucose.

Disaccharide

Sugar formed when two monosaccharides join via a glycosidic linkage; e.g., sucrose.

Polysaccharide

Polymer of many monosaccharides joined by glycosidic bonds; functions in storage or structure.

Glycosidic Linkage

Covalent bond connecting two monosaccharides after dehydration.

Aldose

Monosaccharide whose carbonyl group is at the end of the carbon chain (aldehyde sugar).

Ketose

Monosaccharide with a carbonyl group within the carbon chain (ketone sugar).

Triose

Three-carbon sugar (e.g., glyceraldehyde).

Tetrose

Four-carbon sugar (e.g., erythrose).

Pentose

Five-carbon sugar (e.g., ribose).

Hexose

Six-carbon sugar (e.g., glucose, fructose).

Heptose

Seven-carbon sugar (e.g., mannoheptulose).

Starch

Glucose storage polysaccharide found in plants.

Lipid

Hydrophobic macromolecule class that does not form polymers; includes fats, phospholipids, steroids.

Hydrophobic

Water-repelling due to non-polar covalent bonds.

Fat (Triglyceride)

Energy-rich lipid made of glycerol and three fatty acids.

Glycerol

Three-carbon alcohol forming the backbone of fats.

Fatty Acid

Hydrocarbon chain with a carboxyl group; one of the two building blocks of fats.

Phospholipid

Lipid with two fatty acids and a phosphate-containing head; major component of cell membranes.

Phospholipid Bilayer

Double layer arrangement of phospholipids with hydrophobic tails inward and hydrophilic heads outward in membranes.

Steroid

Lipid characterized by four fused carbon rings (e.g., cholesterol, certain hormones).

Protein

Polymer of amino acids that performs most cellular functions.

Amino Acid

Organic molecule with amino, carboxyl, hydrogen, and R group; monomer of proteins.

Essential Amino Acids

Nine amino acids that cannot be synthesized by the body and must be obtained from diet.

Non-Essential Amino Acids

Five amino acids that can be synthesized by the body under normal conditions.

Conditionally Essential Amino Acids

Six amino acids normally synthesized by the body but required from diet under stress or disease.

Antibody

Specialized protein that identifies and neutralizes foreign antigens in the immune system.

Contractile Protein

Protein (e.g., actin, myosin) responsible for muscle contraction and cellular movement.

Enzyme

Protein catalyst that speeds up metabolic reactions.

Hormonal Protein

Messenger protein that coordinates bodily activities (e.g., insulin-like growth factor, cortisol).

Structural Protein

Protein that supports cell or body structure (e.g., collagen, cytoskeleton).

Storage Protein

Protein that stores amino acids or other substances (e.g., ferritin stores iron).

Transport Protein

Protein that carries molecules within organisms (e.g., hemoglobin transports oxygen).

Primary Structure (Protein)

Unique sequence of amino acids in a polypeptide chain.

Secondary Structure

Regular coils or folds (α-helix, β-pleated sheet) stabilized by hydrogen bonds in the backbone.

Alpha (α) Helix

Coiled secondary structure stabilized by hydrogen bonds every fourth amino acid.

Beta (β) Pleated Sheet

Secondary structure where parallel polypeptide strands are connected by hydrogen bonds.

Tertiary Structure

Overall 3-D shape of a polypeptide formed by interactions among R groups.

Disulfide Bridge

Strong covalent bond between two cysteine residues that stabilizes tertiary structure.

Quaternary Structure

Protein structure formed by assembly of two or more polypeptide subunits.

Nucleic Acid

Polymer of nucleotides; stores and transmits genetic information (DNA, RNA).

DNA (Deoxyribonucleic Acid)

Double-stranded, helical nucleic acid that stores hereditary information and directs its own replication.

RNA (Ribonucleic Acid)

Single-stranded nucleic acid that helps translate DNA instructions into proteins.

Gene

DNA segment that encodes the amino acid sequence of a polypeptide or functional RNA.

Messenger RNA (mRNA)

RNA molecule that carries genetic information from DNA to ribosomes for protein synthesis.

Transcription

Process of synthesizing RNA from a DNA template.

Translation

Process whereby ribosomes synthesize proteins using mRNA as a template.

Nucleotide

Monomer of nucleic acids composed of a nitrogenous base, a pentose sugar, and a phosphate group.

Purine

Double-ring nitrogenous base (adenine or guanine).

Pyrimidine

Single-ring nitrogenous base (cytosine, thymine, or uracil).

Phosphodiester Linkage

Covalent bond connecting nucleotides between the 3′-OH of one sugar and the 5′-phosphate of the next.

Ribose

Pentose sugar in RNA nucleotides.

Deoxyribose

Pentose sugar in DNA nucleotides lacking one oxygen atom compared with ribose.