AP Biology: Chemistry of Life and Biological Macromolecules

A thorough set of AP Biology vocabulary flashcards covering atomic foundations, functional groups, chemical properties of water, macromolecule structures and synthesis, nucleic acids, and pH.

Matter

Anything that has mass and takes up space.

Element

Matter in its simplest form, which cannot be broken down further by chemical means.

Atom

The smallest component of an element that still displays its particular chemical properties.

Ion

An atom that carries a net positive or negative electrical charge.

Cation

A positively charged ion composed of more protons than electrons.

Anion

A negatively charged ion composed of more electrons than protons.

Compound

A molecule composed of more than one type of chemically bonded element, such as $\text{H}_2\text{O}$.

Organic Compound

A chemical compound that contains carbon and usually hydrogen, such as carbohydrates, proteins, lipids, and nucleic acids.

Inorganic Compound

A chemical compound that lacks carbon, such as water ($\text{H}_2\text{O}$).

Functional Groups

Specific configurations of atoms attached to carbon skeletons that are responsible for the characteristic chemical properties and reactions of organic compounds.

Amino Group

A functional group with the formula $-\text{NH}_2$ (or attached to a carbon skeleton as $\text{R}-\text{NH}_2$) that acts as a base by picking up protons from acids; characteristic of amines and amino acids.

Carbonyl Group

A polar, hydrophilic functional group consisting of a carbon atom double-bonded to an oxygen atom ($\text{C}=\text{O}$); exists as an aldehyde or a ketone.

Aldehyde

A carbonyl compound in which the $\text{C}=\text{O}$ group is located at the end of a carbon skeleton, bonded to a terminal hydrogen.

Ketone

A carbonyl compound in which the $\text{C}=\text{O}$ group is located internally within a carbon chain rather than at the end.

Carboxyl Group

An acidic functional group with the formula $-\text{COOH}$ consisting of a carbonyl group linked to a hydroxyl group; acts as an acid by donating protons to basic compounds.

Hydroxyl Group

A simple polar and hydrophilic functional group with the formula $-\text{OH}$; characteristic of organic compounds known as alcohols.

Phosphate Group

An acidic functional group containing phosphorus bonded to four oxygen atoms; a vital constituent of energy storage molecules like ATP, ADP, and GTP.

Sulfhydryl Group

A functional group with the formula $-\text{SH}$; found in the amino acids methionine and cysteine, where it assists in stabilizing protein tertiary structures.

Polar Molecule

A molecule characterized by an unequal distribution of electrical charge, generating partially positive and partially negative regions (poles).

Nonpolar Molecule

A molecule that carries a neutral overall charge as a result of equal electron sharing between atoms.

Hydrogen Bond

A weak intermolecular attraction formed between a positively charged hydrogen atom in a polar bond and an electronegative atom, such as oxygen.

Cohesion

The intermolecular attraction that causes water molecules to link to one another through hydrogen bonds.

Adhesion

The attraction of water molecules to other substances via hydrogen bonds, such as clinging to plant cell walls to help counter gravity.

Surface Tension

A measure of how difficult it is to stretch or break the surface of a liquid, caused by the cohesive hydrogen bonding of surface water molecules to one another rather than to surrounding air molecules.

Evaporative Cooling

The reduction in surface temperature of an object as water absorbs significant thermal energy to break hydrogen bonds and vaporize (e.g., sweating in humans).

Universal Solvent

A property of water denoting its capacity to dissolve more substances than any other liquid on Earth, allowing it to transport dissolved solutes throughout biological systems.

Monomer

A single molecular subunit that can be joined covalently with other subunits to construct larger polymers.

Polymer

A macromolecule composed of many repeating monomer subunits covalently bonded together.

Dehydration Synthesis

A chemical reaction that links two monomer units together through covalent bonds while releasing one molecule of water for each bond formed.

Hydrolysis

A chemical reaction that breaks the covalent bonds linking monomer units by adding a molecule of water across each cleaved bond.

Lipids

Hydrophobic, nonpolar biological macromolecules containing hydrocarbon tails of $\text{CH}_2$ groups used for long-term energy storage, structural support, and signaling; include fats, oils, steroids, and phospholipids.

Triglyceride

A neutral lipid molecule formed by joining one glycerol molecule to three fatty acid chains through dehydration synthesis reactions.

Glycerol

A three-carbon vertical alcohol backbone containing three hydroxyl groups ($-\text{OH}$) that serves as the anchor for triglycerides and phospholipids.

Saturated Fatty Acid

A fatty acid hydrocarbon chain containing no double bonds, maximizing the number of bonded hydrogens and packing tightly into a solid at room temperature.

Unsaturated Fatty Acid

A fatty acid containing one (monounsaturated) or more (polyunsaturated) double bonds, forming kinks that inhibit tight packing and remain liquid at room temperature.

Phospholipid

A specialized membrane lipid formed by combining a glycerol backbone with two nonpolar fatty acid tails and one polar phosphate head group.

Amphipathic

Possessing both a hydrophilic (water-attracting, polar) region and a hydrophobic (water-repelling, nonpolar) region within the same chemical structure.

Phospholipid Bilayer

A two-layered membrane arrangement where hydrophilic phosphate heads orient toward the external aqueous environment and hydrophobic hydrocarbon tails face inward away from water.

Steroids

A class of lipids defined by a molecular skeleton consisting of four fused carbon rings arranged like chicken-wire fencing; examples include cholesterol and sex hormones.

Cholesterol

A structural membrane steroid that regulates membrane integrity and serves as a chemical precursor for sex hormones like testosterone, progesterone, and estrogen.

Carbohydrates

Organic macromolecules containing carbon, hydrogen, and oxygen with a characteristic $2:1$ ratio of hydrogen to oxygen; used for cellular energy production and structural components.

Monosaccharide

The simplest form of carbohydrate, consisting of a single sugar monomer such as glucose ($\text{C}_6\text{H}_{12}\text{O}_6$) or pentoses ($\text{C}_5\text{H}_{10}\text{O}_5$).

Glucose

A six-carbon monosaccharide ($\text{C}_6\text{H}_{12}\text{O}_6$) that serves as the principal energy substrate during cellular respiration.

Disaccharide

A double sugar consisting of two monosaccharides linked together by a covalent bond formed during dehydration synthesis.

Sucrose

A common plant disaccharide ($\text{C}_{12}\text{H}_{22}\text{O}_{11}$) formed by the chemical combination of glucose and fructose.

Maltose

A disaccharide composed of two covalently bonded glucose molecules, commonly utilized in the brewing of beer.

Lactose

A disaccharide sugar naturally present in dairy products, formed by joining galactose and glucose.

Polysaccharide

A complex carbohydrate polymer composed of hundreds or thousands of monosaccharide units linked together for energy storage or structural support.

Starch

The primary energy storage polysaccharide in plants, synthesized entirely from chains of repeating glucose monomers.

Glycogen

The primary energy storage polysaccharide in animals, formed by linking many glucose molecules together and stored primarily in liver and muscle cells.

Cellulose

A rigid structural polysaccharide composed of glucose chains used by plants to construct cell walls.

Chitin

A structural polysaccharide that serves as an essential building material in the exoskeletons of arthropods, including insects, spiders, and shellfish.

Protein

A biological macromolecule composed of chains of amino acids that serves diverse functions including enzymatic catalysis, structural support, transport, and cellular signaling.

Amino Acid

The fundamental monomer of proteins, consisting of a central carbon bonded to an amino group, a carboxyl group, a hydrogen atom, and a variable R-group.

R-group

The variable side chain of an amino acid that dictates its individual chemical identity and properties (e.g., acidic, basic, polar, or nonpolar).

Peptide Bond

The covalent linkage formed via dehydration synthesis between the carboxyl group of one amino acid and the amino group of an adjacent amino acid in a polypeptide chain.

Nucleic Acids

Polymers composed of nucleotide monomers (DNA and RNA) that encode, store, and transmit heritable genetic information.

DNA

Deoxyribonucleic acid; a double-stranded helical nucleic acid composed of deoxyribose sugar, phosphate, and the nitrogenous bases adenine, guanine, cytosine, and thymine.

RNA

Ribonucleic acid; a typically single-stranded nucleic acid containing ribose sugar, phosphate, and the nitrogenous bases adenine, guanine, cytosine, and uracil.

Purine

A class of nitrogenous bases characterized by a double-ring structure, specifically adenine (A) and guanine (G).

Pyrimidine

A class of nitrogenous bases characterized by a single-ring structure, specifically cytosine (C), thymine (T), and uracil (U).

Double Helix

The structural conformation of DNA determined by James D. Watson and Francis H.C. Crick, consisting of two complementary antiparallel strands of nucleotides connected by hydrogen bonds.

Antiparallel Strands

The structural arrangement in double-stranded DNA where the $5'$ end of one nucleotide strand aligns opposite the $3'$ end of the opposing strand.

Messenger RNA (mRNA)

A type of RNA transcribed from DNA in the eukaryotic nucleus that carries protein-building instructions to the ribosomes.

Transfer RNA (tRNA)

A type of RNA that carries specific amino acids to ribosomes during protein translation.

Ribosomal RNA (rRNA)

A structural and catalytic RNA component of ribosomes that facilitates the translation of genetic code into proteins.

pH Scale

A logarithmic scale ranging from $0$ to $14$ that measures hydrogen ion concentration; values below $7$ are acidic, $7$ is neutral, and values above $7$ are basic.

Membrane Fluidity Regulation

The biochemical adjustment in plants where an increase in temperature (from $22^\circ\text{C}$ to $32^\circ\text{C}$) results in an increase in saturated fatty acids and a decrease in unsaturated fatty acids within membrane phospholipids.