Bio 2B

• Catalyst : A substance that speeds up a reaction without changing the substances produced or being changed itself
• Enzymes : Proteins that act as biological catalysts for a specific reaction or reaction or group of reactions
• Anabolic reactions : A reaction that builds up (synthesis) new molecules in a cell
• Catabolic reaction : A reaction which breaks down substances within a cell
• Metabolism : The sum of the anabolic and catabolic processes in a cell
• Metabolic chain (metabolic pathway) : A series of linked reactions in the metabolism of a cell
• Intracellular enzymes : Enzymes that catalyse reactions within the cell
• Extracellular enzymes : Enzymes that catalyse reactions outside of the cell which they were made
• Activation energy : The energy required for a chemical reaction to get started
• Substrate : The molecule or molecules on which an enzyme acts
• Lock-and-key hypothesis : A model that explains enzyme action by an active site in the protein structure that has a very specific shape; the enzyme and substrate slot together to form a complex in the same way as a key fits in a lock
• Active site : The area of an enzyme that has a specific shape into which the substrate(s) of a reaction fit
• Induced-fit hypothesis : A modified version of the lock-and-key model of enzyme action where the active site is considered to have a more flexible shape; after the substrate enters the active site, the shape of that site changes around it to form the active complex; after the products have left the complex, the enzyme returns to it's inactive, relaxed form
• Molecular activity (turnover number) : The number of substrate molecules transformed per minute of a single enzyme molecule
• Temperature coefficient (Q10) : The measure of the effect of temperature on the rate of a reaction
• Denaturation : The loss of the three-dimensional shape of a protein
• Initial rate of reaction : The measure taken to compare the rates of enzyme-controlled reactions under different conditions
• Mononucleotides : Molecules with three parts - a 5-carbon pentose sugar, a nitrogen-containing base and a phosphate group - joined by condensation reactions
• Adenosine triphosphate (ATP) : A molecule that acts as the universal energy supply molecule in cells; it is made up of adenine, pentose sugar, ribose, and three phosphate groups
• Deoxynucleic acid (DNA) : A nucleic acid that is the genetic material in many organisms
• Ribonucleic acid (RNA) : A nucleic acid that is the genetic material in some organisms and is involved in protein synthesis
• Ribose : A pentose sugar that is part of the structure of RNA
• Deoxyribose : A pentose sugar that is part of the structure of DNA
• Purine base : A base found in the nucleotides that has two nitrogen-containing rings
• Pyrimidine base : A base found in nucleotides that has one nitrogen-containing ring
• Adenine : A purine base found in DNA and RNA
• Guanine : A purine base found in DNA and RNA
• Cytosine : A pyrimidine base found in DNA and RNA
• Thymine : A pyrimidine base found in DNA
• Uracil : A pyrimidine base found in RNA
• Nucleic acids/polynucleotides : Polymers made up of many nucleotide monomer units that carry all the information needed to form new cells
• Complementary base pairs : Complementary purine and pyrimidine bases which align in a DNA helix, with hydrogen bonds holding them together (C-G, A-T)
• Genome : The entire genetic material of an organism
• Conservation replication : A model of DNA replication which suggests that the original double helix reamins intact and in some way instructs the formation of a new, identical double heelix made up of entirely new material
• Semiconservative replication : The accepted model of DNA replication in which the DNA 'unzips' and new nucleotides align along each strand; each new double helix contains one strand of the original DNA and one strand made of new materia
• Isotopes : Different atoms of the same element, with the same number of protons, but different number of neutrons; isotopes have the same chemical properties
• DNA helicase : An enzyme involved in DNA replication that 'unzips' the two strands of the DNA molecules
• DNA polymerase : An enzyme involved in DNA replication that lines up the new nucleotides along the DNA template strands
• Codon : A sequence of three bases in DNA or MRNA
• Messenger RNA (mRNA) : The RNA formed in the nucleus that carries the genetic code out of the cytoplasm