2 (c) Biological molecules

carbon, hydrogen, oxygen

chemical elements present in carbohydrates

carbon, nitrogen, hydrogen, oxygen

chemical elements present in proteins

carbon, hydrogen, oxygen

chemical elements present in lipids

long chains of amino acids

protein structure

fatty acids and glycerol

lipid structure

starch and glycogen from simple sugars

carbohydrates structure

1. Get a piece of food and break it up using a pestle and mortar

2. transfer the ground up food to a beaker and add some distilled water

3. give the mixture a good stir with a glass rod to dissolve some of the food

4. filter the solution using a funnel lined with filter paper to get rid of the solid bits of the food

how to prepare a food sample

a substance which increases the speed of a reaction, without being changed or used up in the reaction

catalyst

biological catalyst for metabolic reactions

enzyme

how temperature changes can affect enzyme function, including changes to the shape of active site

• higher temperature increases the rate at first

• enzymes and substrate have more energy so they move about more and are more likely to collide and form enzyme-substrate complexes

• if it gets too hot some of the bonds holding the enzyme together break

• this changes the shape of the enzyme’s active site so the substrate won’t fit any more

• the enzyme is denatured

substrate only fits into the active site if it is the correct shape

lock and key

how does pH affect enzymes

• if pH is too high or too low, the pH interferes with the bonds holding the enzyme together

• this changes the shape of the active site and denatures the enzyme

• all enzymes have an optimum ph that they work at (typically pH 7)