Chapter 2: Chemistry of Life

Vocabulary flashcards covering key terms from Chapter 2: Chemistry of Life.

Matter

Anything that occupies space and has mass.

Mass

The amount of matter in an object.

Weight

The gravitational force acting on an object of a given mass.

Element

The simplest type of matter with unique chemical properties; composed of atoms of only one kind.

Atom

The smallest unit of an element that retains its chemical properties.

Neutron

Electrically neutral subatomic particle.

Proton

Positively charged subatomic particle.

Electron

Negatively charged subatomic particle.

Nucleus

Center of the atom formed by protons and neutrons.

Electron cloud

Region outside the nucleus where electrons are found; most of the atom's volume is occupied by electrons.

Atomic number

Number of protons in an atom; unique to each element.

Atomic weight

Total number of protons and neutrons in the nucleus.

Mass number

Sum of protons and neutrons in an atom.

Atomic mass

Average mass of all naturally occurring forms of an element.

Isotopes

Atoms of the same element with different numbers of neutrons; same atomic number, different mass number.

Radioactive isotopes

Isotopes that decay and emit radiation; used clinically and in research.

Avogadro's number

6.02 x 10^23; number of particles in one mole.

Mole

Amount of substance containing Avogadro's number of entities (atoms, ions, or molecules).

Molar mass

Mass of one mole of a substance in grams; numerically equal to its atomic/molar mass units.

Valence electrons

Electrons in the outermost shell.

Octet rule

Atoms tend to have eight electrons in their valence shell.

Ionic bond

Bond formed by transfer of electrons from one atom to another.

Covalent bond

Bond formed by sharing of electrons between atoms.

Hydrogen bond

Weak intermolecular force between a hydrogen atom and an electronegative atom (O, N, F).

Cations

Positively charged ions.

Anions

Negatively charged ions.

Ionization

Process by which atoms in solution form ions; bonds break in water.

Solubility

Ability of one substance to dissolve in another.

Dissociation

Ions separate and are surrounded by water molecules.

Electrolyte

Compound that ionizes in water and conducts electricity.

Nonpolar covalent

Covalent bonds where electrons are shared equally.

Polar covalent

Covalent bonds where electrons are shared unequally.

Water

Universal solvent; high specific heat; cohesive and adhesive; participates in chemical reactions.

Cohesion

Attraction between like molecules.

Adhesion

Attraction between unlike molecules.

Suspension

Mixture with large particles that settle out.

Solution

Uniform mixture of solute in solvent at the molecular level.

Solvent

Substance that dissolves the solute.

Solute

Substance dissolved in the solvent.

Mixture

Substances physically combined but not chemically bonded.

Compound

Substance formed when two or more elements bond chemically.

Colloid

Mixture with dispersed particles that remain suspended and can be cloudy.

Acid

Substance that donates protons (H+).

Base

Substance that accepts protons or releases OH-.

Salt

Compound with a cation other than H+ and an anion other than OH-.

Buffer

Solution of a conjugate acid-base pair that resists pH change.

pH

Measure of how acidic or basic a solution is.

Acidic

pH below 7.

Neutral

pH around 7.

Basic

pH above 7.

Bicarbonate

Biological buffer; helps maintain stable pH.

Phosphates

Biological buffers involved in pH regulation.

Protein

Large, essential biomolecule; structure and function depend on proteins.

Amino acids

Building blocks of proteins; 20 standard amino acids; 9 essential.

Essential amino acids

Amino acids that must be obtained from diet.

Peptide bond

Covalent bond linking amino acids in a protein.

Enzyme

Protein that catalyzes chemical reactions by lowering activation energy.

Active site

Region of enzyme where substrate binds.

Cofactor

Non-protein helper molecule that enables enzyme function.

Coenzyme

Organic cofactor.

Nucleic acids

Biomolecules (DNA and RNA) made of nucleotides; store/transmit genetic information.

DNA

Deoxyribonucleic acid; double-stranded genetic material.

RNA

Ribonucleic acid; single-stranded; involved in protein synthesis.

Nucleotides

Monomers of nucleic acids consisting of sugar, base, and phosphate.

ATP

Adenosine triphosphate; cellular energy currency.

Monosaccharide

Simple sugar unit.

Disaccharide

Two monosaccharides linked together.

Polysaccharide

Complex carbohydrate; many sugar units.

Glucose

Primary energy source; a six-carbon monosaccharide.

Fructose

Fruit sugar; converted to glucose.

Galactose

Dairy sugar; converted to glucose.

Sucrose

Table sugar; glucose + fructose.

Lactose

Milk sugar; glucose + galactose.

Maltose

Sugar of two glucose units; maltose.

Glycogen

Storage form of glucose in animals.

Starch

Storage form of glucose in plants.

Cellulose

Structural polysaccharide in plants; indigestible in humans.

Triglyceride

Major lipid; glycerol with three fatty acids.

Glycerol

Alcohol backbone of triglycerides.

Fatty acid

Building block of fats; can be saturated or unsaturated.

Saturated

Fats with only single bonds; typically solid at room temperature.

Unsaturated

Fats with one or more double bonds; typically liquid at room temperature.

Fat

Triglyceride used for energy storage and protection.

Oil

Liquid fat, usually from plant sources.

Phospholipid

Structural unit of cell membranes; amphipathic with polar head and nonpolar tail.

Steroid

Lipid with four-ring structure; includes cholesterol, bile salts, estrogens, and testosterone.

Cholesterol

Steroid component of membranes and precursor to other steroids.

Bile salts

Steroid-derived molecules aiding digestion.

Estrogen

Steroid sex hormone in females.

Testosterone

Steroid sex hormone in males.

Primary structure

Linear sequence of amino acids in a protein.

Secondary structure

Local folding patterns; alpha-helix and beta-pleated sheet.

Alpha-helix

Right-handed helical secondary structure.

Beta-pleated sheet

Sheet-like secondary structure.

Tertiary structure

Overall three-dimensional folding of a protein.

Quaternary structure

Assembly of multiple protein subunits into a functional complex.