Campbell Biology in Focus - Chapter 3: Carbon and the Molecular Diversity of Life

A complete set of vocabulary flashcards covering the key terms and concepts from Chapter 3 of Campbell Biology in Focus (Carbon and the Molecular Diversity of Life).

Valence

The number of covalent bonds an atom can form, determined by its electron configuration.

Hydrocarbons

Organic molecules consisting of only carbon and hydrogen atoms.

Functional Groups

Specific chemical groups that affect molecular function by being directly involved in chemical reactions in characteristic ways.

Polymer

A long molecule consisting of many similar or identical building blocks linked by covalent bonds.

Monomers

Small building-block molecules that serve as the repeating units of a polymer.

Condensation Reaction

A chemical reaction in which two molecules are covalently bonded to each other with the loss of a small molecule.

Dehydration Reaction

A reaction in which two monomers become covalently bonded together through the loss of a water molecule ($H_2O$).

Hydrolysis

A chemical process that disassembles polymers into monomers by the addition of a water molecule, essentially reversing dehydration.

Carbohydrates

A class of biological molecules that includes sugars and the polymers of sugars.

Monosaccharides

The simplest carbohydrates, or simple sugars, which generally have molecular formulas that are multiples of $CH_2O$.

Glucose

The most common monosaccharide, with the chemical formula $C_6H_{12}O_6$, serving as a major nutrient for cells.

Disaccharide

A double sugar formed when a dehydration reaction joins two monosaccharides.

Glycosidic Linkage

A covalent bond formed between two monosaccharides by a dehydration reaction.

Polysaccharides

Carbohydrate macromolecules composed of many sugar building blocks, functioning in cellular storage and structural roles.

Starch

A storage polysaccharide of plants consisting entirely of glucose monomers linked together, stored as granules within cellular plastids.

Glycogen

An extensively branched storage polysaccharide in animals, stored primarily in liver and muscle cells.

Cellulose

A structural polysaccharide composed of unbranched chains of $\beta$ glucose monomers that serves as a major structural component of tough plant cell walls.

Chitin

A structural polysaccharide found in the exoskeletons of arthropods and the cell walls of many fungi.

Lipids

A diverse class of hydrophobic biological molecules that do not form true polymers and are not large enough to be considered macromolecules.

Fat (Triacylglycerol)

A lipid composed of three fatty acids linked to one glycerol molecule via ester linkages.

Fatty Acid

A molecule consisting of a carboxyl group attached to a long carbon skeleton, differing in length and in the number and position of double bonds.

Ester Linkage

A covalent bond formed between a hydroxyl group of glycerol and a carboxyl group of a fatty acid via a dehydration reaction.

Saturated Fatty Acids

Fatty acids that have no double bonds between carbon atoms and possess the maximum possible number of hydrogen atoms, typically remaining solid at room temperature.

Unsaturated Fatty Acids

Fatty acids containing one or more double bonds that cause bending, typically remaining liquid at room temperature.

Trans Fats

Fats produced by synthetically adding hydrogen to unsaturated fats, resulting in molecules with trans double bonds that can contribute to coronary heart disease.

Phospholipids

Lipid molecules made of two fatty acid tails (hydrophobic) and a phosphate group (hydrophilic) attached to a glycerol backbone, forming bilayer structures in cell membranes.

Steroids

Lipids characterized by a carbon skeleton consisting of four fused carbon rings.

Cholesterol

A crucial animal steroid found in cell membranes and acting as a precursor molecule from which other steroids are synthesized.

Catalysts

Chemical agents, such as enzymatic proteins, that selectively speed up chemical reactions without being consumed in the reaction.

Polypeptides

Unbranched polymers built from the same common set of 20 amino acids.

Protein

A biologically functional molecule consisting of one or more polypeptides twisted, folded, and coiled into a specific three-dimensional conformation.

Amino Acids

Organic molecules possessing both an amino group and a carboxyl group attached to an alpha ($\alpha$) carbon, distinguished from one another by unique side chains (R groups).

Peptide Bond

The covalent bond formed between the carboxyl group of one amino acid and the amino group of another through a dehydration reaction.

Gene Expression

The cellular process by which DNA directs the synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis.

Nucleotide

The repeating monomer unit of nucleic acids, consisting of a pentose sugar, a nitrogenous base, and one or more phosphate groups.

Nucleoside

The portion of a nucleotide molecule consisting solely of a nitrogenous base and a pentose sugar, lacking any phosphate group.

Pyrimidines

A family of nitrogenous bases featuring a single six-membered ring, comprising cytosine (C), thymine (T), and uracil (U).

Purines

A family of nitrogenous bases featuring a six-membered ring fused to a five-membered ring, comprising adenine (A) and guanine (G).

Phosphodiester Linkage

The covalent bond linking adjacent nucleotides in a polynucleotide chain, formed between the sugar of one nucleotide and the phosphate group of the next.

Antiparallel

The structural arrangement of DNA strands in a double helix where the two sugar-phosphate backbones run in opposite $5' \rightarrow 3'$ directions relative to one another.

Complementary Base Pairing

The specific hydrogen bonding pairing rule in nucleic acids: adenine (A) pairs with thymine (T) in DNA or uracil (U) in RNA, and guanine (G) pairs with cytosine (C).