[15] Biological molecules

what chemical elements are present in carbohydrates

carbon, hydrogen and oxygen

what chemical elements are present in proteins

carbon, hydrogen, oxygen, nitrogen and sulfur

what chemical elements are present in lipids

carbon, hydrogen and oxygen

what are carbohydrates made of give me examples

simple sugars called monosaccharides e.g glucose and fructose

what are proteins made of give me examples

amino acids which are small molecules, some contain sulfur

what are lipids made of give me examples

fatty acids and glycerol

what is the test for glucose?

add blue benedict’s solution to test tube with sample in a water bath, if glucose is present it will turn orange-brown

what is the test for starch

add drop organge-brown iodine solution to starch, if starch is present it will turn blue-black, if it is not present it will stay the same

what is the test for protein

add a few drops of copper sulphate solution then add a few drops of sodium hydroxide solution if protein is present the solution should turn from blue to lilac purple

what is the test for fats?

add ethanol to cooking oil, shake test tube then add drops of water and shake again. if fat is present an emulsion will form turning the solution cloudy milky white colour

when testing for foods what precautions do you need to take?

wear goggles

what are some safety precautions you need to take for the fats test?

ethanol is highly flammable, so you should use water baths instead of bunsen burners, keep away from burning flames

what is starch?

chain of glucose

what are enzymes and what do they do

biological catalysts that speed up chemical reactions in the body.

how are enzymes affected by changes in temperature

at temperatures above optimum temperature enzymes denature. at optimum temperature they work effectively and at low temperatures enzyme reaction rates are slower as they have less kinetic energy

how are enzymes affected by changes in pH?

Most enzymes work best at pH 7, which is their optimum pH. However, different enzymes have different optimum pH’s, depending on the environment they are in

how can the effect of temperature on enzyme activity be investigated

add a known amount of starch into 3 test tubes, place these three tubes into 3 different water baths at different temperatures. use another syringe to add amylase solution into three more test tubes and add each of the 3 water baths. add iodine in a spotting tile. after a known amount of time, pour the amylase into the starch suspension in each water bath and swirl the contents. take one drop from a tube with starch and amylase and add it to the iodine on the spotting tile. repeat.

how can the effect of pH on enzyme activity be investigated

Prepare buffer solutions at different pH levels. Mix amylase with each buffer then add starch solution and start timing. take samples every known time period and add them to iodine solution in a spotting tile. The iodine turns blue-black if starch is present and stays brown/orange if it’s not. repeat the experiment for each pH and average the results to determine the optimum pH for amylase activity.