Video Notes: Water, Carbon, and Biomolecules (Ch. 3–5)

Vocabulary flashcards covering key terms and definitions from pages 1–5 notes on water, carbon, and biomolecules.

solution

A completely homogeneous mixture of two or more substances.

solvent

The dissolving agent of a solution.

solute

The substance dissolved in the solvent.

aqueous solution

A solution in which the solute is dissolved in water.

hydration shell

Sphere of water molecules around each dissolved ion.

hydration

Process by which water molecules surround and interact with dissolved ions or molecules.

hydrophilic

Water-loving; substances that dissolve in water or are attracted to water.

hydrophobic

Water-fearing; nonpolar substances that repel water.

molecular mass

Sum of the masses of all the atoms in a molecule.

molarity

The number of moles of solute per liter of solution.

hydrogen bond

A strong attraction between a hydrogen atom and an electronegative atom (e.g., in water, between molecules).

hydrogen ion (H+)

A single proton; highly reactive species that increases acidity.

hydroxide ion (OH-)

A negatively charged hydroxide ion formed when water loses a proton.

hydronium ion (H3O+)

A water molecule that has gained a proton; acts as the active acidic form in solution.

dynamic equilibrium

A reversible chemical state where forward and reverse reactions occur at the same rate.

acid

Substance that increases the H+ concentration of a solution.

base

Substance that decreases the H+ concentration of a solution (often by increasing OH-).

basic solution

A solution with a higher concentration of OH- than H+.

neutral solution

A solution with equal concentrations of H+ and OH-.

pH

A measure of acidity; pH = -log[H+], where [H+] is the hydrogen ion concentration.

buffers

Substances that maintain stable pH by absorbing or releasing H+ as needed.

ocean acidification

CO2 dissolving in seawater forms carbonic acid, lowering seawater pH.

carbonate/bicarbonate balance in ocean

Extra H+ forms bicarbonate, reducing carbonate ions needed for calcification.

carbon skeleton

The carbon framework of an organic molecule; length, branching, or rings vary.

hydrocarbons

Organic molecules consisting only of carbon and hydrogen.

isomers

Compounds with the same formula but different structures and properties.

structural isomers

Isomers that differ in covalent arrangements of atoms.

cis-trans isomers

Geometric isomers around a double bond; cis = same side, trans = opposite sides.

enantiomers

Stereoisomers that are mirror images of each other and can have different biological effects.

asymmetric carbon

A carbon atom attached to four different groups, creating chirality.

functional group

A specific group of atoms with characteristic properties that participate in reactions.

hydroxyl group (–OH)

Polar group; forms hydrogen bonds; typically makes an alcohol; suffix -ol.

carbonyl group (>C=O)

A carbon double-bonded to oxygen; found in ketones and aldehydes.

ketose

Sugars with a carbonyl group within the carbon skeleton.

aldose

Sugars with an aldehyde group at the end of the carbon skeleton.

carboxyl group (–COOH)

Acidic group that donates a proton (H+).

amino group (–NH2)

Basic group that can accept a proton (H+).

sulfhydryl group (–SH)

Thiol group; can form disulfide bonds that stabilize protein structure.

phosphate group (–OPO3^2−)

Negatively charged group; can release energy when reacting with water; important in energy transfer.

methyl group (–CH3)

Group that can affect gene expression and the function of hormones when attached to DNA or proteins.

ATP (adenosine triphosphate

Energy-carrying molecule with three phosphate groups; releases energy upon hydrolysis.

macromolecules

Large polymeric biomolecules (carbohydrates, proteins, nucleic acids); lipids are large but not polymers.

polymer

Long molecule made of repeating monomer units covalently bonded.

monomer

A smaller molecule that is the building block of a polymer.

dehydration (condensation) reaction

A reaction that links monomers by forming a covalent bond with the loss of a water molecule.

hydrolysis

The breaking down of polymers by adding a water molecule.

carbohydrates

Sugars and their polymers; provide energy and structural support.

monosaccharide

Simple sugar with formula CH2O; basic unit of carbohydrates.

glucose

A six-carbon aldose sugar with multiple hydroxyl groups.

fructose

A six-carbon ketose sugar; isomer of glucose.

disaccharide

Two monosaccharides linked by a glycosidic linkage.

glycosidic linkage

Covalent bond formed between two monosaccharides via dehydration.

maltose

Disaccharide composed of two glucose units.

sucrose

Disaccharide composed of glucose and fructose; common table sugar.

lactose

Disaccharide composed of glucose and galactose; milk sugar.

polysaccharide

Many monosaccharides linked; serves as storage material or structural component.

starch

Plant storage polysaccharide made of glucose units.

glycogen

Animal storage polysaccharide stored in liver and muscle cells.

cellulose

Plant cell wall polysaccharide; structural carbohydrate.

chitin

Carbohydrate used by arthropods for exoskeletons.

lipids

Nonpolar, hydrophobic biomolecules; do not form true polymers; energy storage, membranes, hormones.

fat (triglyceride)

Glycerol bonded to three fatty acids; primary energy storage and cushioning.

glycerol

Three-carbon alcohol backbone of fats.

fatty acid

Long hydrocarbon chain with a terminal carboxyl group; part of fats.

saturated fatty acid

No double bonds between carbon atoms; maximum hydrogen; usually solid at room temperature.

unsaturated fatty acid

One or more double bonds; fewer hydrogens; usually liquid at room temperature.

trans fat

Hydrogenated unsaturated fats with trans double bonds; associated with health risks.

phospholipid

Lipid with two fatty acids and a phosphate-containing head; forms cell membranes.

bilayer

Two-layered sheet formed by phospholipids in water; fundamental structure of membranes.

steroids

Lipids with a fused four-ring carbon skeleton; diverse roles, including hormone precursors.

cholesterol

A steroid component of animal cell membranes and precursor to other steroids.

ester linkage

Bond formed between glycerol and fatty acid in fats during dehydration synthesis.