Key Terms Chapter 3 Campbell Biology In Focus

• Organic chemistry- special study of chemistry dealing with molecules containing carbon and hydrogen
• Hydrocarbon- an organic molecule consisting only of carbon and hydrogen.
• Functional groups- a specific configuration of atoms commonly attached to the carbon skeletons of organic molecules and involved in chemical reactions.
• Hydroxyl group: a chemical group consisting of an oxygen atom joined to a hydrogen atom. Molecules possessing this group are soluble in water and are called alcohols.
• Carbonyl groups: a chemical group present in aldehydes and ketones and consisting of a carbon atom double-bonded to an oxygen atom.
• Carboxyl group: a chemical group present in organic acids and consisting of a single carbon atom double-bonded to an oxygen atom and also bonded to a hydroxyl group.
• Amino group: a chemical group consisting of a nitrogen atom bonded to two hydrogen atoms; can act as a base in solution, accepting a hydrogen ion and acquiring a charge of 1+.
• Sulfhydryl group: a chemical group consisting of a sulfur atom bonded to a hydrogen atom.
• Phosphate group: a chemical group consisting of a phosphorous atom bonded to four oxygen atoms; important in energy transfer.
• Methyl group: a chemical group consisting of a carbon bonded to three hydrogen atoms. The methyl group may be attached to a carbon or to a different atom.
• Macromolecule: a giant molecule formed by the joining of smaller molecules, usually by a dehydration reaction. Polysaccharides, proteins, and nucleic acids are macromolecules.
• Polymer: a long molecule consisting of many similar or identical monomers linked together by covalent bonds.
• Monomer: the subunit that serves as the building block of a polymer.
• Condensation (dehydration) reaction: a chemical reaction in which two molecules become covalently bonded to each other with the removal of a water molecule.
• Hydrolysis: a chemical reaction that breaks bonds between two molecules by the addition of water; functions in disassembly of polymers to monomers.
• Carbohydrate: a sugar (monosaccharide) or one of its dimers (disaccharides) or polymers (polysaccharides).
• Monosaccharide: the simplest carbohydrate, active alone or serving as a monomer for disaccharides and polysaccharides. Also known as simple sugars, monosaccharides have molecular formulas that are generally some multiple of CH2O.
• Disaccharide: a double sugar, consisting two monosaccharides joined by a glycosidic linkage formed by a dehydration reaction.
• Glycosidic linkage: a covalent bond formed between two monosaccharides by a dehydration reaction.
• Polysaccharide: a polymer of many monosaccharides, formed by dehydration reactions.
• Starch: a storage polysaccharide in plants, consisting entirely of glucose monomers joined by glycosidic linkages.
• Glycogen: an extensively branched glucose storage polysaccharide found in the liver and muscle of animals; the animal equivalent of starch.
• Celluose: a structural polysaccharide of plant cell walls, consisting of glucose monomers joined by Beta glycosidic linkages.
• Chitin: a structural polysaccharide consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods.
• Lipid: any group of large biological molecules, including fats, phospholipids, and steroids, that mix poorly, if at all, with water.
• Fat: a lipid consisting of three fatty acids linked to one glycerol molecule; also called a triacylglycerol or triglyceride.
• Fatty acid: a carboxylic acid with a long carbon chain. Fatty acids vary in length and in the number and location of double bonds; three fatty acids linked to a glycerol molecule form a fat molecule, also known as a triacylglycerol or triglyceride.
• Triglyceride: (triacylglycerol) a lipid consisting of three fatty acids linked to one glycerol molecule, also called a fat.
• Saturated fatty acid: a fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, thus maximizing the number of hydrogen atoms attached to the carbon skeleton.
• Unsaturated fatty acid: a fatty acid that has one or more double bonds between carbons in the hydrocarbon tail. Such bonding reduces the number of hydrogen atoms attached to the carbon skeleton.
• Phospholipid: a lipid made up of glycerol joined to two fatty acids and a phosphate group. The hydrocarbon chains of the fatty acids act as nonpolar, hydrophobic tails, while the rest of the molecule acts as a polar, hydrophilic head. Phospholipids form bilayers that function as biological membranes.
• Cholesterol: a steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids, such as many hormones.
• Protein: a biologically functional molecule consisting of one or more polypeptides folded and coiled into a specific three dimensional structure.
• Enzyme: a macromolecule serving as a catalyst, a chemical agent that increases the rate of a reaction without being consumed by the reaction. Most enzymes are proteins.
• Polypeptide: a polymer of many amino acids linked together my peptide bonds.
• Amino acid: an organic molecule possessing both a carboxyl and an amino group. Amino acids serve as the monomers of polypeptides.
• Peptide bond: the covalent bond between the carboxyl group on one amino acid and the amino group on another, formed by a dehydration reaction.
• Primary structure: the level of protein structure referring to the specific linear sequence of amino acids.
• Secondary structure: regions of repetitive coiling or folding of the polypeptide backbone of a protein due to hydrogen bonding between constituents of the backbone (not side chains).
• Tertiary structure: the overall shape of a protein molecule due to interactions of amino acid side chains, including hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bonds.
• Quaternary structure: the particular shape of a complex, aggregate protein, defined by the characteristic three-dimensional arrangement of its constituent subunits, each a polypeptide.
• Denaturation: in proteins, a process in which a protein loses its native shape due to the disruption of weak chemical bonds and interactions, thereby becoming biologically inactive; in DNA, the separation of the two strands of the double helix. Denaturation occurs under extreme (noncellular) conditions of pH, salt concentration, or temperature.
• Chaperone protein:
• Nucleic acid: a polymer (polynucleotide) consisting ot many nucleotide monomers; serves as a blueprint for proteins and, through the actions of proteins, for all cellular activities. The two types are DNA and RNA.
• DNA: (deoxyribonucleic acid) a nucleic acid molecule, actually a double-stranded helix, in which each polynucleotide strand consists of nucleotide monomers with a deoxyribose sugar and the nitrogenous base adenine (A), cytosine (C), guanine (G), and thymine (T); capable of being replicated and determining the inherited structure of a cell’s proteins.
• RNA: (ribonucleic acid) a type of nucleic acid consisting of a polynucleotide made up of nucleotide monomers with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U); usually single stranded; functions in protein synthesis, gene regulation and as the genome for some viruses.
• Nucleotide: the building block of a nucleic acid, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and one or more phosphate groups.
• Pyrimidine: one of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring. Cytosine (C), thymine (T), and uracil (U) are pyramidines.
• Purine: one of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring fused to a five-membered ring. Adenine (A) and guanine (G) are purines.