Chapter 4) Biological molecules

Biological molecules

chemicals found in living organisms

Macromolecule

large molecule made from smaller units

Carbohydrate

molecule made of carbon, hydrogen and oxygen; used for energy

Glucose

simple sugar used in respiration

Starch

storage carbohydrate in plants

Glycogen

storage carbohydrate in animals

Cellulose

carbohydrate forming plant cell walls

Protein

molecule made of amino acids; used for growth and repair

Amino acid

building block of proteins

Enzyme

protein that speeds up chemical reactions

Lipid

fats and oils used for energy storage and insulation

Fat

lipid that is solid at room temperature

Oil

lipid that is liquid at room temperature

Water

essential molecule, solvent, transport medium and involved in reactions

Inorganic

not containing carbon (e.g. water, mineral ions)

Organic

containing carbon (e.g. carbohydrates, proteins, lipids)

Food test

method used to detect biological molecules

Benedict’s test

test for reducing sugars; blue to green/yellow/orange/brick-red when heated

Reducing sugar

sugar that reacts with Benedict’s solution (e.g. glucose)

Iodine test

test for starch; orange-brown to blue-black

Biuret test

test for protein; blue to purple/lilac

Ethanol emulsion test

test for lipids; clear to milky white emulsion

Vitamin C test (DCPIP)

blue solution turns colourless if vitamin C is present

Balanced diet

diet containing correct proportions of nutrients

Malnutrition

lack of proper nutrition due to imbalance of nutrients

Fibre

aids movement of food through the gut (roughage)

Mineral ions

inorganic elements needed in small amounts (e.g. calcium, iron)

Calcium

needed for strong bones and teeth

Iron

needed to make haemoglobin

Vitamin

organic molecules needed in small amounts for health

Vitamin C

needed for healthy skin and gums; deficiency causes scurvy

Vitamin D

needed for calcium absorption; deficiency causes rickets