Carbohydrates, Lipids, and Biochemical Tests PDF

CARBOHYDRATES Made up of carbon, hydrogen and oxygen One molecule of carbohydrates contains twice as many hydrogens atoms as carbon or oxygen atoms Sugars are simplest type of carbohydrates. They taste sweet and are soluble in water.  Functions of carbohydrates...

CARBOHYDRATES Made up of carbon, hydrogen and oxygen One molecule of carbohydrates contains twice as many hydrogens atoms as carbon or oxygen atoms Sugars are simplest type of carbohydrates. They taste sweet and are soluble in water.  Functions of carbohydrates 1. As a substrate for respiration, provides energy for cell activities 2.To form supporting structures, for example cell wall in plant cells 3. To be converted into other organic compounds such as amino acids and fats 4. For the formation of nucleic acid, for example DNA  Monosaccharides are single sugar molecules which act as building blocks of disaccharides and polysaccharides. The disaccharides are sugar molecules composed of two monosaccharides. Polysaccharides are composed of number of monosaccharides linked together. Cellulose Hydrolysis - Splitting of a large molecule into smaller ones by addition of water Hydrolysis of DISACCHARIDES Condensation-The combining of two small molecules to make a larger molecule with the removal of water molecules. Condensation reaction occurs when a molecule of water is lost. Two monosaccharides join in a condensation reaction to form a disaccharide. glucose + glucose → maltose + water glucose + fructose → sucrose + water galactose + glucose → lactose + water  GLYCOGEN Glucose dissolved in blood plasma is delivered to every cell of the body. Why do cell needs glucose? Glucose molecules are linked together in chains to form larger molecules of glycogen. The liver helps to keep the concentration of glucose in the blood constant, if there is too much glucose, the liver links glucose to make glycogen. Glycogen is stored in the liver cells and is broken down into glucose when the body needs.  STARCH In plants, glucose molecules are linked in a different way to make starch. Starch is stored in plant cells. It is broken down into glucose again when the plants need it.  Cellulose Plant also make another carbohydrate, CELLULOSE Cellulose is also made of many glucose molecules linked in a chain but they form straight lines instead of coiling in a spiral (like starch) Cellulose is used in making ___________. Structure of starch,glycogen and cellulose Why are glycogen and starch better storage materials? 1.insoluble- do not change osmotic pressure 2.large molecules-do not diffuse through cell membranes. 3.easily hydrolysed when glucose is needed. 4.compact shapes-more glucose can be stored in less space. COLOUR CHANGE From brown/orange to blue black Starch is present Some food samples may need to be crushed before adding iodine. TEST FOR GLUCOSE: 1. Put equal volumes of glucose and Benedict's solution. COLOUR CHANGE 2. Heat over a boiling water bath. Blue (as benedict is blue) 3. Observe the colour change in the solution. Green Yellow Orange-red (brick red/orange) Gradual colour change, orange -red indicates that a lot of glucose is present. The Benedict’s Test also helps in identifying REDUCING and NON-REDUCING sugars. All reducing sugars will turn Benedict orange-red when heated together. Non-reducing sugars will give a negative result.The solution will stay blue.  LIPIDS (Fats and Oils) Fats and Oils are also known as lipids. Fat (a lipid that is solid at room temperature) Oil ( a lipid that is liquid at room temperature) Chemical composition: _ _ _ (same as carbs but different proportions, less oxygen than in carbohydrates) Each fat molecule is made of a glycerol molecule and three molecules of fatty acids.(triglyceride)  Functions/ Importance of Fats 1) Provide insulation/reduces heat loss/maintains temperature 2) Protect vital organs against mechanical damage/cushions the organs/shock absorber 3) Used as source of energy 4) Used as store of energy 5) It is an essential part of cell, especially in cell membranes