Chapter 4 - Biological molecules Flashcards
What chemical elements are carbohydrates made up of?
Carbon, oxygen, and hydrogen
What chemical elements are proteins made up of?
All contain carbon, oxygen, hydrogen, and nitrogen and some contain sulphur
What chemical elements are lipids made up of?
Carbon, oxygen, and hydrogen
What are carbohydrates made of?
Carbohydrates are long chains of simple sugars. Glucose is a simple sugar (monosaccharide). When 2 glucose molecules join together, maltose is formed (a disaccharide). When lots of glucose molecules join together, starch, glycogen and cellulose can be made (a polysaccharide).
What are lipids made of?
Lipids in the body are made up of triglycerides. Their basic unit is 1 glycerol molecule chemically bonded to 3 fatty acid chains. The fatty acids vary in size and structure. Lipids are divided into fats which are solid at room temperature and oils which are liquids in room temperature.
What are proteins made of?
Proteins are long chains of amino acids. There are about 20 different amino acids. They all contain the same basic structure, but the ‘R’ group is different for each one. When amino acids are joined together, a protein is formed, and these amino acids can be arranged in any order, resulting in hundreds of thousands of different proteins.
What does benedict’s solution test for?
Benedict’s solution tests for glucose (a reducing sugar). Process: add benedict’s solution into sample solution in test tube, heat at 60-70 degrees in a water bath for 5 minutes, take the test tube out of the water bath and observe the colour. A positive test will show a change from blue to orange/brick red.
What does iodine test for?
Iodine tests for starch. Process: add drops of iodine solution to the food sample. A positive test will show a colour change from orange/brown to blue/black.
What does biuret solution test for?
Biuret solution tests for protein. Process: add drops of biuret solution to the food sample. A positive test will show a colour change from blue to violet/purple.
What does ethanol test for?
Ethanol tests for lipids. Process: a food sample is mixed with 2cm^3 of ethanol and shaken. The ethanol is added to an equal volume of cold water. A positive test will show a cloudy emulsion forming.
What does DCPIP test for?
DCPIP tests for vitamin C. process: add 1cm^3 of DCPIP solution to a test tube. Add a small amount of food sample (as a solution). A positive test will show the blue colour of the die disappearing. (blue to colourless)
What is DNA?
DNA consists of two strands of DNA wound around each other in what is called a double helix. Each strand contains chemicals called bases. Bonds between the pairs of bases hold the strands together. They always pair up the same way – A with T and C with G.
