Nutrition

Nutrition Autotrophic Nutrition (Plants) Autotrophic organisms make their own food and are not dependant on other organisms for nutrition. Green plants take in inorganic substances and combine them to form organic materials such as sugars. Heterotrophic Nutrition (Animals) Heterotrophic organisms feed on substances made by other living organisms. Animals obtain food by feeding on organic substances that are made by plants, or by feeding on other organisms that have obtained their food from plants. Carbohydrates Consist of carbon, hydrogen and oxygen. Used to release energy during respiration and for the storage of chemical energy. Monosaccharides (Such as glucose) Simplest carbohydrate consisting of only one molecule. Soluble and taste sweet Glucose: C6H12O6 Main energy source for cells Releases energy during respiration (Mitochondria) Carbohydrates are transported in the blood through the body as glucose. Building block to create larger carbohydrate molecules (disaccharides and polysaccharides) Starting molecule for creation of other molecules such as amino acids and fatty acids. Stored as glycogen in the body. Dissaccharides (Such as maltose) Two monosaccharide subunits joined together form a disaccharide. Maltose: Two glucose molecules joined together. Sucrose: Carbohydrates are transported in the phloem tubes of plants as sucrose. Dissaccharide of one glucose and one fructose subunits. Polysaccharides (Such as starch) Many monosaccharide subunits joined together form a complex molecule called a polysaccharide. Most are insoluble and do not taste sweet. Glycogen and starch: Storage forms of glucose. Can readily be borken down when energy is needed. Cellulose: Main material of plant cell walls. Keeps the cell rigid and prevents the cell from bursting when turgid. Glycosidic Bonds Subunits of monosaccharides in disaccharides and polysaccharides are kept together by a chemical bond called a glycosidic bond. Bonds are created during a condensation reaction. Bonds are broken during a hydrolysis reaction. Condensation reaction (Bond-creating): A molecule of water is removed in the bond-creating reaction. 4767580299085(Monosaccharide) 00(Monosaccharide) Subunit OH HO Subunit 10534652540(Monosaccharide) 00(Monosaccharide) 416623523685500 417512510985500244094024638000244094010985500234632510985500 314642525463500 H2O Subunit O Subunit 20942307620(Glycosidic bond) 00(Glycosidic bond) 2157095205740(Disaccharide) 00(Disaccharide) Hydrolysis reaction (Bond-breaking): 2369820130175(Disaccharide) 00(Disaccharide) A molecule of water is added in the bond-breaking reaction. 48145701597025(Monosaccharide) 00(Monosaccharide) 11061701597660(Monosaccharide) 00(Monosaccharide) 216979557150(Glycosidic bond) 00(Glycosidic bond) 543941037846000251841012763500025184101273175004232910127317500241236535941000322516569342000Subunit OH HO Subunit H2O Subunit O Subunit Proteins Contain carbon, hydrogen, oxygen, nitrogen and some sulphur and phosphorus. Used to make enzymes, hormones and are used to repair damaged cells and create new cells. Not normally used to provide energy. Amino Acids Subunits for larger polpeptide chains and proteins. 2216150267335“R” represents one of twenty possible side chains. This determines which one of the twenty possible amino acids it is. 00“R” represents one of twenty possible side chains. This determines which one of the twenty possible amino acids it is. There are twenty different possible amino acids. 12128593345N H H C H R C O OH Amino Group Carboxyl Group 00N H H C H R C O OH Amino Group Carboxyl Group Polypeptide Chains A series of amino acids bonded together by peptide bonds. Proteins A number of polypeptide chains that are joined together make a protein molecule. There are millions of possible proteins. Each protein has a unique 3-dimensional shape which is determined by: Kind, number and sequence of amino acids in the chain. Different forces of attraction between different parts of the molecule that make it coil and fold into its unique shape. When a protein is heated or exposed to strong chemicals, the bonds that hold its shape can be broken. When the shape of a protein changes permenantly, it cannot function and is said to be denatured. There are two main types of protein: Fibrous Globular Fibrous protein: Main structural and supporting materials. Strong and insoluble in water. Long, spirally coiled chains held in place by hydrogen bonds. Examples: Keratin Hair, nails, wool, claws, beak and horn Fibrin In blood plasma to trap red blood cells for the process of blood clotting. Collagen Connective tissue, tendons, ligaments and in bones for greater tensile stregnth. Globular protein: Majority of proteins. Soluble in water. Chain is folded over and around itself to form a spherical shape. Examples: Enzymes (the folds of the chain create the active site.) Hormones Antibodies Carrier proteins (Cell surface membrane) Haemoglobin Table of functions of some globular proteins: Example Function Where it occurs Amylase An enzyme – breaks down starch into maltose. Salivary glands Insulin A hormone – regulates glucose metabolism Produced in pancreas, works in liver Haemoglobin Oxygen transport Red blood cells Immunoglobulins Antibodies – fight invading antigens Blood plasma Draw and label diagrams of fibrous and globular proteins from textbook: rightbottomGlobular protein Polypeptide chain folds in on itself. 00Globular protein Polypeptide chain folds in on itself. leftbottomFibrous protein Amino acid Hydrogen bond Polypeptide chain forms a spiral. 00Fibrous protein Amino acid Hydrogen bond Polypeptide chain forms a spiral. Peptide Bonds Amino acid subunits in polypeptide chains and proteins are kept together by a chemical bond called a peptide bond. A peptide bond is created between the amino group of the one subunit and the carboxyl group of the other. Bonds are created during a condensation reaction. Bonds are broken during a hydrolysis reaction. Condensation reaction (Bond-creating): (Amino Acid – R1) (Amino Acid – R2) N C H R1 C N H H C H R1 C O H O OH N H H C H R1 C O OH O N H H C H R2 C OH (Dipeptide) H2O (Peptide Bond) A molecule of water is removed in the bond-creating reaction. Hydrolysis reaction (Bond-breaking): 2183130188595(Dipeptide) 00(Dipeptide) A molecule of water is added in the bond-breaking reaction. N H H C H R1 C O OH N H H C H R2 C OH N C H R1 C N H H C H R1 C O H O OH H2O 2188845131445(Peptide Bond) 00(Peptide Bond) 5322570221615O 00O 4149725230505(Amino Acid – R1) 00(Amino Acid – R1) 1107440233045(Amino Acid – R1) 00(Amino Acid – R1) Lipids Contain carbon, hydrogen and oxygen. A group of organic compounds that are insoluble in water. Two important types: Triglycerides (Fats and oils) Phospholipids (In cell surface membrane) Triglycerides (Fats and oils): Mainly used as a source of energy and for the storage of energy. Releases twice as much energy per gram as a carbohydrate or protein. Consists of: Three fatty acid molecules 31559527241500One glycerol molecule Three fatty acid molecules Glycerol molecule Condensation (Bond-creating) and hydrolysis (Bond-breaking) reaction: center259715Glycerol + fatty acid + fatty acid + fatty acid Condensation -3H2O Hydrolysis +3H2O Glycerol - fatty acid - fatty acid - fatty acid 00Glycerol + fatty acid + fatty acid + fatty acid Condensation -3H2O Hydrolysis +3H2O Glycerol - fatty acid - fatty acid - fatty acid Phospholipids: Consists of: One glycerol molecule that contains a phosphate group called the hydrophilic (water-loving) head. Two fatty acid molecules called the hydrophobic (water-hating) tail. The hydrophilic heads face outwards from the cell surface membrane whereas the hydrophobic tails are between the two layers of hydrophilic heads. This keeps the two substances on either side of the membrane separate as the hydrophobic tails repel the water and other substances, creating a barrier. 54419534290Water Hydrophilic heads Hydrophobic tails Water 00Water Hydrophilic heads Hydrophobic tails Water Food Tests Reducing Sugars – The Benedict’s test Benedict’s solution contains copper salts and is blue in colour. All monosaccharides and some dissaccharides are reducing sugars. The reason this test works and the reason that they are called reducing sugars is because the sugars reduce the copper salts in the Benedict’s solution. The test: Add crushed test food into test tube with small amount of water to make a solution. Add same amount of Benedict’s solution as water. Boil carefully. Results: Large amount of reducing sugar Brick red Small amount of reducing sugar Greeny-yellow No reducing sugar Stays blue Non-reducing Sugars – Hydrolysis and the Benedict’s test The test: Add crushed test food into test tube with small amount of water to make a solution. Add very small amount of hydrochloric acid and boil gently. Use litmus paper sodium hydrogencarbonate to neutralise the solution. Perform Benedict’s test as mentioned above. Results: Large amount of non-reducing sugar Brick red Small amount of non-reducing sugar Greeny-yellow No non-reducing sugar Stays blue Protein – Biuret test The test: Add crushed test food into test tube with small amount of water to make a solution. Add same amount of 5% potassium hydroxide solution as water. Add two drops of 1% copper sulphate solution. Shake gently. Results: Protein present Purple/violet No protein Stays blue Fats and oils – Emulsion test The test: Add crushed test food into test tube with ethanol and shake gently. Pour this ethanol and food mixture into cold water. Results Fat present Cloudy white emulsion