Chapter 3: Nucleic Acids, Proteins, and Enzymes
Terms in this set (54)
activation energy (Ea)
The energy barrier that blocks the tendency for a chemical reaction to occur.
The region on the surface of an enzyme or ribozyme where the substrate binds, and where catalysis occurs.
A nitrogen-containing base found in nucleic acids, ATP, NAD, and other compounds.
Regulation of the activity of a protein (usually an enzyme) by the binding of an effector molecule to a site other than the active site.
Î± (alpha) helix
A prevalent type of secondary protein structure; a right-handed spiral.
An organic compound containing both NH2 and COOH groups. Proteins are polymers of amino acids.
In nucleic acids, the purine or pyrimidine that is attached to each sugar in the sugarâ€"phosphate backbone.
Î² (beta) pleated sheet
A type of protein secondary structure; results from hydrogen bonding between polypeptide regions running antiparallel to each other.
A chemical substance that accelerates a reaction without itself being consumed in the overall course of the reaction. Catalysts lower the activation energy of a reaction. Enzymes are biological catalysts.
An inorganic ion that is weakly bound to an enzyme and required for its activity.
A nonsubstrate that binds to the active site of an enzyme and thereby inhibits binding of its substrate. (Contrast with noncompetitive inhibitor.)
complementary base pairing
The AT (or AU), TA (or UA), CG, and GC pairing of bases in double-stranded DNA, in transcription, and between tRNA and mRNA.
A nitrogen-containing base found in DNA and RNA.
Loss of activity of an enzyme or a nucleic acid molecule as a result of structural changes induced by heat or other means.
A five-carbon sugar found in nucleotides and DNA.
The covalent bond between two sulfur atoms (â€"Sâ€"Sâ€") linking two molecules or remote parts of the same molecule.
DNA (deoxyribonucleic acid)
The fundamental hereditary material of all living organisms. In eukaryotes, stored primarily in the cell nucleus. A nucleic acid using deoxyribose rather than ribose.
The creation of a new strand of DNA in which DNA polymerase catalyzes the exact reproduction of an existing (template) strand of DNA.
A catalytic protein that speeds up a biochemical reaction.
enzymeâ€"substrate complex (ES)
An intermediate in an enzyme-catalyzed reaction; consists of the enzyme bound to its substrate(s).
A mechanism for regulating a metabolic pathway in which the end product of the pathway can bind to and inhibit the enzyme that catalyzes the first committed step in the pathway. Also called end-product inhibition.
free energy (G)
Energy that is available for doing useful work, after allowance has been made for the increase or decrease of disorder.
A unit of heredity. Used here as the unit of genetic function which carries the information for a polypeptide or RNA.
The complete DNA sequence for a particular organism or individual.
A nitrogen-containing base found in DNA, RNA, and GTP.
A series of enzyme-catalyzed reactions so arranged that the product of one reaction is the substrate of the next.
A nonsubstrate that inhibits the activity of an enzyme by binding to a site other than its active site. (Contrast with competitive inhibitor.)
A polymer made up of nucleotides, specialized for the storage, transmission, and expression of genetic information. DNA and RNA are nucleic acids.
The basic chemical unit in nucleic acids, consisting of a pentose sugar, a phosphate group, and a nitrogen-containing base.
Peptide made up of less than 20 amino acids.
Increase in positive charge of an element by removing electron(s); formation of an oxide by adding oxygen.
The bond between amino acids in a protein; formed between a carboxyl group and amino group (â€"COâ€"NHâ€") with the loss of water molecules.
Molecule containing two or more amino acids.
The connection in a nucleic acid strand, formed by linking two nucleotides.
A large molecule made up of many amino acids joined by peptide linkages. Large polypeptides are called proteins.
The specific sequence of amino acids in a protein. (Contrast with secondary, tertiary, quaternary structure.)
Long-chain polymer of amino acids with twenty different common side chains. Occurs with its polymer chain extended in fibrous proteins, or coiled into a compact macromolecule in enzymes and other globular proteins.
One of the two types of nitrogenous bases in nucleic acids. Each of the purinesâ€"adenine and guanineâ€"pairs with a specific pyrimidine.
One of the two types of nitrogenous bases in nucleic acids. Each of the pyrimidinesâ€"cytosine, thymine, and uracilâ€"pairs with a specific purine.
The specific three-dimensional arrangement of protein subunits. (Contrast with primary, secondary, tertiary structure.)
Gain of electrons by a chemical reactant; any reduction is accompanied by an oxidation. (Contrast with oxidation.)
The distinguishing group of atoms of a particular amino acid. Also known as a side chain.
A five-carbon sugar in nucleotides and RNA.
RNA (ribonucleic acid)
An often single-stranded nucleic acid whose nucleotides use ribose rather than deoxyribose and in which the base uracil replaces thymine found in DNA. Serves as genome from some viruses. (See ribosomal RNA, transfer RNA, messenger RNA, ribozyme.)
Of a protein, localized regularities of structure, such as the Î± helix and the Î² pleated sheet. (Contrast with primary, tertiary, quaternary structure.)
The R group of the amino acid.
(1) The molecule or molecules on which an enzyme exerts catalytic action. (2) The base material on which a sessile organism lives.
The scientific study of an organism as an integrated and interacting system of genes, proteins, and biochemical reactions.
In reference to a protein, the relative locations in three-dimensional space of all the atoms in the molecule. The overall shape of a protein. (Contrast with primary, secondary, quaternary structures.)
Nitrogen-containing base found in DNA.
The synthesis of RNA using one strand of DNA as a template.
In an enzyme-catalyzed reaction, the reactive condition of the substrate after there has been sufficient input of energy (activation energy) to initiate the reaction.
The synthesis of a protein (polypeptide). Takes place on ribosomes, using the information encoded in messenger RNA.
A pyrimidine base found in nucleotides of RNA.