C- BIOLOGICAL MOLECULES

Structure of food molecules

• starch & glycogen are made from small sugars

• proteins are made from amino acids

• lipids are made from fatty acids & glycerol

Food test for starch

• place sample onto a spotting tile

• add iodine

• the positive result forms a dark, blue-black colour

Food test for glucose

• place sample into a test tube, add water to dissolve & add Benedict’s solution

• place test tube into a hot water bath

• positive result— solution goes from blue to brick red

Biuret test for protein

• take sample and add some water

• add biuret solution (potassium hydroxide solution + copper sulfate solution)

• positive result will be a purple color

Test for lipids

• place sample in a test tube and add ethanol

• cover the end of the tube and shake vigorously

• pour this solution into water

• positive result is a milky-white emulsion

What do enzymes do?

They break down large biological molecules into smaller molecules so they can pass from the intestine into the blood

Nutrients & their respective enzymes

• protease – proteins to amino acids

• lipase – lipids to fatty acids & glycerol

• maltase – maltose into glucose

• amylase – starch into maltose

how do enzymes work?

they act as biological catalysts to speed up reactions without getting used up themselves. a substrate will attach to the enzyme’s active site, the reaction will happen and the products will leave the active site. vital because they allow reactions to happen with less energy. each enzyme has an active site unique to its substrate, and if temperatures get too high, the enzyme will denature and no longer fit its substrate