food

• autotroph - an organism that can make its own food
• heterotroph - an organism that cannot make its own food
• nutrients - chemical substances found in food that are used by organisms
• nutrients important for - a source of energy , as raw materials for growth and repair of cells (protein), to make chemical needed for metabolic reaction
• six common elements - carbon, nitrogen, hydrogen, phosphorus, oxygen, sulphur
• elements found dissolved in salts - sodium, chlorine and calcium
• three trace elements found in tiny amounts - iron, copper, zinc
• carbohydrates - carbon, hydrogen and oxygen - fixed ratio
• monosaccharides - smallest unit of carbs - consist of one sugar unit eg. glucose
• monosaccharides are all sweet to taste and are soluble in water
• disaccharides - consists of two sugar units joined together eg. glucose + glucose = maltose
• disaccharides are also sweet and are soluble in water
• mono and disccharides play no structural role in the body only a metabolic one
• polysaccharides - constist of many monosaccharides joined together eg. starch
• polysaccharides - insoluble or only slightly soluble in water
• cellulose - polysaccharides - made from long chains of glucose molecules bonded together with lots of cross-bonding
• starch - made from long straight chains of glucose molecules - stored in plants found in bread, flour and potatoes
• gylcogen - polysacchrides - made from long branched chains of glucose molecules -stored in animals in the liver and muscle
• structural function of carbs - cellulose cell walls in plants
• Metabolic function of carbs - glucose is used to produce energy in respiration, glycogen is an energy store in animals, starch is an energy stored in plants
• lipids contain carbon hydrogen and oxygen - no particular ratio and do not contain much oxygen
• lipids include fats - solid at room temperature - and oils - liquid at room temperature
• a triglyceride is the basic unit of lipid
• every triglyceride is made up of a single glycerol with 2 fatty acids attached
• a phospholipid has the same structure as a triglyceride except that one of the fatty acids is replaced by a phosphate group
• metabolic function of lipids - to provide energy
• structural function of lipids - to form a protective layer around organs like the heart, phospholipids form part of the cell membrane, provide insulation
• sources of lipids - butter, oil and cream
• protein - contains elements carbon, hydrogen, oxygen and nitrogen
• protein sometimes contains small amounts of sulphur and phosphorus
• protein - elements combine to form amino acids
• The function of amino acids depends on the amino acid sequence and on the way that they are folded
• 20 common amino acids
• amino acids are bonded together via peptide bonds to form protein
• a peptide is a small chain of amino acids (less than 20)
• a polypeptide has more than 20 amino acids
• a protein is a long polypeptide (at least 200 amino acids)
• function of structural proteins - fibrous - keratin forms our skin, hair and nails
• fibrous proteins are long straight chains of amino acids that have very few foldings - play a structural role
• Functions of Metabolic proteins - all enzymes are made from protein - enzymes alter the rate of chemical reactions without getting used in the reaction itself (catalast)