Biological Molecules Glossary Flashcards
Amino Group
Each amino acid has the same fundamental structure, which consists of a central carbon atom which is bonded to an amino group (NH2), a carboxyl group (COOH) and to a hydrogen atom.
Benedict’s test
the test for reducing sugars,
- Approximately 1 ml of sample is placed into a clean test tube.
- 2 ml (10 drops) of Benedict’s reagent (CuSO4) is placed in the test tube.
- The solution is then heated in a boiling water bath for 3-5 minutes.
- Observe for colour change in the solution of test tubes or precipitate formation.
A positive result is indicated by a brick-red colouration.
Biuret test
the test for protein, it detects peptide bonds,
- at room temperature, place a sample of the solution to be tested in a test tube and add an equal volume of sodium hydroxide.
- add a few drops of very dilute (0.05%) Copper (II) Sulfate and mix gently.
- A purple colouration indicates the presence of peptide bonds, if no protein is present the solution remains blue.
Carboxyl group
Each amino acid has the same fundamental structure, which consists of a central carbon atom which is bonded to an amino group (NH2), a carboxyl group (COOH) and to a hydrogen atom.
Condensation reaction
The reaction that takes monomers and bonds them to form polymers - H2O given off
Disaccharide
2 bonded monosaccharide molecules
Disulphide bonds
disulphide bonds are formed by the oxidation of two cysteine residues to form a covalent sulfur-sulfur bond
Emulsion test
Test for lipids:
- Take a completely dry and grease-free test tube.
- Add 2cm^3 of the sample being tested, add 5cm^3 of ethanol.
- Shake the tube thoroughly to dissolve any lipid in the sample.
- Add 5cm^3 of water and shake gently.
- A cloudy-white colour indicates the presence of a lipid.
- As a control, repeat the procedures using water instead of the sample, the final solution should be clear.
Fructose
A monosaccharide, a sweet tasting soluble substance with a general formula of C6H12O6
Galactose
A monosaccharide, a sweet tasting soluble substance with a general formula of C6H12O6
Glucose
A monosaccharide, a sweet tasting soluble substance with a general formula of C6H12O6
Glycerol
A colourless, odourless liquid, with a sweet taste. Glycerol is seen in biological systems as an intermediate carbohydrate and lipid metabolism
Glycosidic Bond
a type of covalent bond that joins a carbohydrate molecule to another group
Hydrogen Bond
a weak bond between two molecules resulting from an electrostatic attraction between a proton in one molecule and an electronegative atom in the other
Hydrolysis
A chemical process of decomposition involving the splitting of a bond by the addition of water
Hydrophilic
a hydrophilic molecule is one whose interactions with water and other polar substances are more thermodynamically favourable than their interactions with oil or other hydrophobic solvents
Hydrophobic
Hydrophobic molecules and surfaces repel water. Hydrophobic liquids, such as oil, will separate from water. Hydrophobic molecules are usually nonpolar, meaning the atoms that make the molecule do not produce a static electric field.
Ionic bonds
A type of chemical bonding that involves the electrostatic attraction between oppositely charged ions, or between two atoms with sharply different electronegatives, and is the primary interaction occurring in ionic compounds
Lactose
a sugar found in milk, it is a disaccharide containing glucose and galactose molecules
Maltose
a disaccharide made of two glucose molecules
Monomer
a molecule that can be bonded to other identical molecules to form a polymer e.g. glucose
Monosaccharide
any of the class of sugars (e.g. glucose) that cannot be hydrolysed to give a simple sugar
Mono-unsaturated fatty acid
MUFAs are a type of unsaturated fat. ‘mono’ meaning ‘one’ signifies that monosaturated fats only have one double carbon bond
Non-reducing sugar
a carbohydrate that is not oxidized by a weak oxidizing agent in basic aqueous solution (e.g. sucrose)
