Biological Molecules Flashcards

Vocabulary flashcards covering biological molecules including the properties of water, types of saccharides, lipid structure, and core practical biochemical tests.

Dipole

A separation of charge due to electrons in covalent bonds being unevenly shared, resulting in a molecule with one negatively charged end and one positively charged end.

Hydrogen bonds

Weak bonds that form between the positive (δ+) and negatively (δ-) charged regions of nearby water molecules; they are constantly breaking and reforming in liquid water.

Cohesion

The attraction of water molecules to each other, allowing them to pull other water molecules along.

Adhesion

The ability of water molecules to form hydrogen bonds with other molecules, such as the sides of a vessel.

Polymerisation

The process by which small, single subunits called monomers bond with many repeating subunits to form large molecules called polymers.

Monosaccharides

Simple carbohydrate monomers and sugars including triose ($3C$), pentose ($5C$), and hexose ($6C$) sugars.

Alpha ($\alpha$) glucose

A form of glucose that has the hydrogen ($H$) atom above carbon 1 and the hydroxyl group ($OH$) below carbon 1.

Beta ($\beta$) glucose

A form of glucose that has the hydrogen ($H$) atom below carbon 1 and the hydroxyl group ($OH$) above carbon 1.

Maltose

A disaccharide containing two molecules of glucose linked by a $1,4$ glycosidic bond.

Sucrose

A disaccharide containing a molecule of glucose and a molecule of fructose linked by a $1,2$ glycosidic bond.

Lactose

A disaccharide containing a molecule of glucose and a molecule of galactose linked by a $1,4$ glycosidic bond.

Amylose

An unbranched helix-shaped polysaccharide in starch containing $1,4$ glycosidic bonds between $\alpha$-glucose molecules.

Amylopectin

A branched polysaccharide in starch containing $1,4$ glycosidic bonds and $1,6$ glycosidic bonds between $\alpha$-glucose molecules.

Glycogen

The highly branched storage polysaccharide of animals and fungi, containing both $1,4$ and $1,6$ glycosidic bonds for quick storage or release of glucose.

Benedict’s reagent

A blue solution containing copper (II) sulfate ions ($CuSO_4$) used to test for reducing sugars.

Reducing sugar

A sugar able to donate electrons to another substance, such as the copper (II) sulfate in Benedict's reagent.

Colorimeter

An instrument that beams a specific wavelength of light through a sample to measure the absorbance or transmission of light to establish quantitative data.

Serial dilutions

A series of dilutions of a stock solution where the concentration decreases by the same quantity between each test tube.

Iodine test

A qualitative test for starch where orange/brown iodine solution turns blue-black if starch is present.

Glycosidic bond

A strong covalent bond formed when two hydroxyl ($OH$) groups on different monosaccharides interact.

Condensation reaction

A chemical reaction that results in the formation of a covalent bond and the release of one water molecule.

Hydrolysis reaction

A reaction where a covalent bond is broken by the addition of water ($Hydro$ = water, $Lysis$ = to break).

Triglycerides

Non-polar, hydrophobic lipids formed by one glycerol molecule and three fatty acids joined by ester bonds.

Ester bond

A bond formed by a condensation reaction between the hydroxyl ($-OH$) group of glycerol and the carboxyl group ($-COOH$) of a fatty acid.

Saturated fatty acids

Fatty acids containing no carbon-carbon double bonds, forming unbranched, linear hydrocarbon chains.

Unsaturated fatty acids

Fatty acids containing one or more carbon-carbon double bonds, which can be mono or poly-unsaturated.