Unit 1: Biological Molecules & Properties of Water

Comprehensive vocabulary flashcards covering Unit 1 biological molecules, water properties, enzyme activity, pH, carbohydrates, lipids, proteins, and nucleic acids.

Cohesion

The attraction between water molecules causing them to stick to each other due to hydrogen bonding.

Adhesion

The attraction of water molecules to different polar substances, allowing water to stick to surfaces like plant xylem tubes or glass vessels.

Specific Heat Capacity of Water

The amount of heat energy required to change the temperature of water, equal to $4200\,J/(kg \cdot ^\circ C)$, which acts as a body temperature regulator.

Universal Solvent

The property of water stemming from its polarity that allows it to dissolve polar molecules and transport ions, nutrients, and waste in biological organisms.

Surface Tension

The result of cohesive forces between water molecules at the surface pulling on each other to form a tight, elastic surface layer.

Acid

A substance that dissociates in solution to release $H^+$ ions, possessing a pH value less than $7$.

Base

A substance that dissociates in solution to release $OH^-$ ions, possessing a pH value greater than $7$.

Buffer

A chemical or biological system that resists changes in pH to maintain a constant, neutral pH in biological systems.

Catalase

An enzyme found in liver cells that breaks down hydrogen peroxide ($H_2O_2$) into water ($H_2O$) and oxygen gas ($O_2$).

Denaturation

The process in which an enzyme or protein loses its functional three-dimensional active site shape due to extreme pH or temperature.

Monomer

A single unit molecule or building block that links with other similar units to form a polymer.

Polymer

A large macromolecule composed of a repeating sequence of monomer building blocks.

Dehydration Synthesis

A chemical reaction that joins monomers together to build polymers, releasing a water molecule ($H_2O$) in the process.

Hydrolysis

A chemical reaction that breaks polymers down into individual monomers through the addition of a water molecule ($H_2O$).

Monosaccharide

A single sugar monomer with the empirical chemical formula $C_n H_{2n} O_n$, such as glucose, fructose, or galactose.

Disaccharide

A sugar formed by joining two monosaccharides through dehydration synthesis, such as maltose, sucrose, or lactose.

Polysaccharide

A complex carbohydrate polymer composed of many linked monosaccharide units, such as starch, glycogen, or cellulose.

Starch

A storage polysaccharide used by plants to store excess glucose.

Glycogen

A highly branched polysaccharide carbohydrate used by animals to store excess glucose in the liver.

Cellulose

A structural polysaccharide that forms plant cell walls.

Lipid

A non-polar biological molecule that does not mix freely with polar solvents like water.

Neutral Fat (Triglyceride)

A lipid molecule synthesized by dehydration synthesis joining $1$ glycerol molecule to $3$ fatty acid chains.

Saturated Fatty Acid

A non-polar hydrocarbon chain containing no double bonds ($C=C$), full of hydrogen, produced by animals, and solid at room temperature.

Unsaturated Fatty Acid

A non-polar hydrocarbon chain containing double bonds ($C=C$) with fewer hydrogens, produced by plants, and liquid at room temperature.

Trans Fat

An unsaturated fatty acid containing a trans double bond configuration around its carbon-carbon double bond ($C=C$).

Phospholipid

A lipid consisting of a polar hydrophilic phosphate-containing head and two non-polar hydrophobic fatty acid tails, serving as an integral structural component of cell membranes.

Steroid

A non-polar lipid characterized by a four-ring carbon structure, including cholesterol and sex hormones like testosterone.

Amino Acid

The monomer unit of proteins consisting of a central carbon atom, an amine group ($-NH_2$), a carboxyl group ($-COOH$), a hydrogen atom, and a variable R-group.

Peptide Bond

A strong covalent bond formed between the carboxyl group of one amino acid and the amine group of another via dehydration synthesis.

Primary Structure

The linear sequence of amino acids linked together by peptide bonds in a polypeptide chain.

Secondary Structure

The folding or coiling of a polypeptide chain into an alpha helix or beta pleated sheet stabilized by hydrogen bonds along the backbone.

Tertiary Structure

The 3D shape of a single folded polypeptide chain held together by covalent, ionic, and hydrogen bonds among R-groups.

Quaternary Structure

The protein structure resulting from the assembly and interaction of two or more individual tertiary polypeptide subunits, such as in hemoglobin.

Nucleotide

The monomer unit of nucleic acids consisting of a 5-carbon sugar, a phosphate group, and a nitrogenous base.

DNA (Deoxyribonucleic Acid)

A double-stranded, double-helical nucleic acid containing deoxyribose sugar and nitrogenous bases adenine (A), thymine (T), cytosine (C), and guanine (G).

RNA (Ribonucleic Acid)

A single-stranded nucleic acid containing ribose sugar and nitrogenous bases adenine (A), uracil (U), cytosine (C), and guanine (G).

Complementary Base Pairing

The specific hydrogen bonding between nitrogenous base pairs in nucleic acids (adenine with thymine/uracil, and cytosine with guanine).

Adenosine Triphosphate (ATP)

A nucleotide derivative that serves as the general energy currency molecule of cells.