Biological Molecules Flashcards
(14 cards)
Describe Benedicts Test
Add 2cm3 of solution to 2cm3 of food sample in a test tube. Shake the mixture. heat the contents in a boiling water bath for 2-3 minutes.
Name the complex carbohydrates
Starch, cellulose and glycogen
Name the single sugars
Glucose and fructose
Name the double sugars
Maltose and sucrose
Why are starch and glucose suitable storage materials?
-Insoluble in water
-Large molecules that cannot diffuse through cell membranes
-Easily hydrolysed to glucose when needed
-Made of molecules that have compact shapes, so they occupy lesser space
Formula for Carbs
CnH2mOm
Functions of carbohydrates
-Substrate for respiration to provide energy for cell activities
-Form supporting structures like cell wall
-To be converted into other organic compounds such as amino acids and fats
Results of iodine test
Starch is present = Blue-black
Starch is absent = Brown
Functions of fats
-Source and long term storage of energy (Fats have higher energy value)
-Insulating material to prevent excessive heat loss
-Solvent for fat soluble vitamins and some hormones
Describe ethanol emulsion test
(Liquid sample)
-Add 2cm3 of ethanol to a drop of liquid sample in a test tube and shake the mixture thoroughly
-Add 2cm3 of water into mixture and shake
(Solid sample)
-Crush sample into small pieces then add the ethanol
-Decant the ethanol into another test tube containing 2cm3 of water and shake
Structure of protein
Peptide bonds link up amino acids to form a polypeptide. 2 or more polypeptide chains fold to form a 3D molecule called protein
Functions of protein
-Synthesises new protoplasm for growth and repair of worn out cells
-Synthesises enzymes and some hormones
-Synthesises antibodies
Describe biuret test
Add 2cm3 of biuret solution to 2cm3 of food sample to a clean test tube. Shake well and allow the mixture to stand for 5 minutes
Biuret test results
Proteins are present = Violet solution
Proteins are absent = Blue solution
