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Created by siobhan.quirk
over 11 years ago
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Question | Answer |
Define covalent bonds | are formed when electrons are shared between atoms. These bonds are very strong. Covalently bonded atoms form new molecules. |
Define carbohydrates | make up a group of molecules containing carbon, hydrogen and oxygen in the ratio Cn(H2O)n |
Define polysaccharide | polymers of monosaccharides. Consist of hundreds of monosaccharide monomers bonded together to form a large molecule |
Define cellulose | a carbohydrate polymer made by bonding beta-glucose molecules together in a long chain |
Define amino acids | monomers of all proteins. All amino acids have the same basic structure. The 20 different amino acids involved in protein synthesis differ only in the R-group bonded to the central carbon |
Define primary structure | the specific sequence of amino acids that make up a protein |
Define secondary sequence | coiling and pleating of parts of the polypeptide molecule |
Define tertiary structure | the overall 3D structure of the final polypeptide or protein molecule |
Define haemoglobin | globular transport protein |
Define collagen | a fibrous structural protein |
Define lipids | a group of chemicals that dissolve in organic solvents, such as alcohol but NOT water. Include fatty acids, triglycerides and cholesterol |
Define triglyceride | one glycerol molecule and three fatty acids |
Define hydrogen bond | a weak interaction that can occur whenever molecules contain a slightly negative atom bonded to a slightly positive hydrogen. |
Define food tests | simple tests that show the presence of various biological molecules in samples or structures. Iodine can stain plant tissue sections to show where starch is |
Define quantitative test | a measure of substance in units |
Define assay techniques | are often use to compare measurements with known samples so that quantitative measurements can be made |
Define nucleotides | monomers of nucleic acids. Each nucleotide is formed by bonding toher a phosphate group, a sugar molecule and a nitrogenous base |
Define DNA | stable polynucleotide molecule. Acts as information store because the bases projecting from the backbone act as a coded sequence. Organisms differ in their DNA only because they contain different sequences of bases in the DNA |
Define gene | a length of DNA that codes for one polypeptide. Each gene occupies a specific place on a chromosome. |
Define allele | different versions of the same gene |
Define catalyst | a molecule that speeds up a chemical reaction but does not get used up. At the end of the reaction the catalyst remains unchanged. |
Define extracellular | enzymes catalyse reactions outside the cell |
Define intracellular | enzymes catalyse reactions inside the cell |
Define activation energy | the amount of energy that must be applied for a reaction to proceed. Different reactions have different activation energies. Enzymes lower the activation energy |
Define denaturation | changes to the tertiary structure of an enzyme such that it cannot function and its function cannot be restored. The primary structure is not affected |
Define optimum pH | the pH value at which the rate of an enzyme controlled reaction is at its maximum. Each enzyme has a different optimum pH |
Define limiting factor | if all other conditions are kept constant, increasing concentration of that factor alone will inrease the reaction rate |
Define enzyme inhibitor | any substance or molecule that slows down the rate of an enzyme-controlled reaction by affecting the enzyme molecule in some way |
Define cofactor | any substance that must be present to ensure enzyme-controlled reactions take place at the appropriate rate. Some cofactors are a part of the enzyme (prosthetic groups), others are temporary (coenzymes and inorganic ion cofactors) |
Define biosensor | uses enyme-controlled reactions to deect the presence of substances in a highly sensitive and specific way. If the substance is present, the enzyme-controlled reaction takes place. The biosensor has a mechanism for revealing whether a product is made |
Define variable | any factor that may change and therefore affect the reaction rate |
Define anomalous | a result that looks out of place compared with other results |
Define turnover number | the number of reactions an enzyme molecule can catalyse in one second. In catalase the turnover number is up to 200 000 |
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