CHEMICAL COMPOSITION OF THE CELL

CHEMICAL COMPOSITION OF THE CELLPREPARED BY : TEACHER FEEFECHEMICAL COMPOUNDS IN THE CELLCHEMICAL COMPOUNDSORGANIC COMPOUNDS-CARBOHYDRATES-PROTEINSLIPIDSNUCLEIC ACIDINORGANIC COMPOUNDS-WATER-MINERAL SALTSCARBOHYDRATESIs an organic compounds which contain 3 elements : carbon, hydrogen, and oxygen.Carbohydrates are large organic molecules made from many smaller basic unites called saccharides (glucose unit Large molecules can be split into smaller units by a reaction called hydrolysis which is addition of water.These smaller unit can be join together again by condensation which removal of water.3 main types of carbohydrates are monosaccharides, disaccharides and polysaccharides. Monosaccharides + protein = glycoproteinMonosaccharides + lipids = glycolipidsCARBOHYDRATES (MONOSACCHARIDES)Simple sugar, cannot be broken down further.General formula (CH2O)n where n = 3, 5, 6 carbon atomsThe most common monosaccharides are 6 atom carbon (hexones) with formula (C6H12O6)Properties of monosaccharides include having sweet taste, soluble in water and crystalisedMonosaccharides are the building block of complex carbohydrates. Main source of energy All monosaccharides are reducing sugar. Act as reducing agent in Benedicts test.

CARBOHYDRATES (TEST FOR REDUCING SUGAR)When 2ml of a sugar solution is heated with 2ml of blue Benedicts solution in a test tube, a brick precipitate is formed.Reason : Benedicts solution contain blue copper (II) sulphate. The sugar reduces the Cu2+ in the Benedicts solution to Cu+ of the brick-red precipitate copper(I) oxides,

Examples monosaccharides : glucose, fructose, galactoseCARBOHYDRATES (DISACCHARIDES)Formula C12H22O11Disaccharides are 2 molecules monosaccharides combine together through condensation with removal of water.Broken down by addition of water which is hydrolysis. Examples : maltose, lactose, sucrose

Glucose + glucose maltose + waterGlucose + fructose sucrose + waterGlucose + galactose lactoe + waterCARBOHYDRATES (DISACCHARIDES)Disaccharides taste sweet, soluble in water and crystalised.Maltose and lactose are reducing sugar, sucrose are not reducing sugarTEST FOR NON REDUCING SUGAR2ml dilute hydrochloric acid is added to 2ml sucrose solution in a test tube and boiled for a few minutes and then cooled.A little sodium hydrogen carbonate powder is added to neutralised the acid.2ml of Benedicts solution is added and the solution is heated for 2 minutes. A brick precipitate formed. CARBOHYDRATES (POLYSACCHARIDES)Complex carbohydrates.Polymers which contain long chain of monosaccharides.General formula (C6H10O5)n where n= 40 or several thousandsPolysaccharides do not taste sweet, insoluble, do not form crystals.Examples : starch, glycogen, celluloseCARBOHYDRATES (POLYSACCHARIDES)POLYSACCHARIDESUBUNITSTRUCTUREOCCURRENCE

STARCH main plant storage compound.Glucose Unbranced, helix chain of glucose unitsRice, wheat, bread, maize, potatoCELLULOSE main component in cell wallGlucose Straight chains of glucose unitsPlant cell wallsGLYCOGEN main animal storage compoundGlucoseShort branched chain of glucose unit.Muscle and liver cells of animals and fungi.CARBOHYDRATES (IMPORTANCE)Supply energy to the cell through respirationAs the main food storag- starch in plant and glycogen in animalCellulose builds cell wall inplant cells and as an important sources of fibres in food.PROTEINContain carbon, hydrogen, oxygen, and nitrogen. Some protein also contain sulphur and phosphorus.Main source are from milk , meat, egg, fish, beans and nutBasic unit are amino acidThere are 20 types of amino acid in nature.Two amino acid join together by peptide bond to produce dipeptide.Many amino acid link together to form polypeptide chain. They fold and twist to form specific proteins.PROTEINS (GROUPS)GROUP OF AMINO ACIDCLASS OF AMINO ACIDPROPERTIESEXAMPLEESSENTIAL AMINO ACID (9 AMINO ACID)FIRST CLASS PROTEIN (ANIMAL PROTEIN)Cannot be produced by the human body but can only obtain in our diet)Valine (Val)Leucine (Leu)Tryptophan (Try)NON-ESSENTIAL AMINO ACID (11 AMINO ACID)SECOND CLASS PROTEINS (PLANT PROTEIN)Can be produced by our bodyAlanine (Ala)Glycine ( Gly)Glutamine ( Glu)PROTEIN (STRUCTURES)PROTEIN STRUCTUREDESCRIPTIONEXAMPLEPRIMARY STRUCTURELinear sequence of amino acid in polypeptide chainHormone insulinSECONDARY STRUCTUREPolypeptide chain coil to form - helix chain or pleat to form -pleated sheetsKeratin, collagenTERTIARY STRUCTUREHelix chain and pleated sheets are folded into a 3 dimensional shapePlasma protein, enzymes, antibodies, hormonesQUATERNARY STRUCTUREMany polypeptide chains combine with non protein groups to form a large complex protein moleculeHaemoglobin, chlorophyll

PROTEIN (IMPORTANCE)Build muscle for movementTo make the protoplasmGrowth and repairMake enzymeForm hormonesForm antibodiesForm haemoglobin

LIPIDS

Contain carbon, hydrogen and oxygen.Types of lipid are fats, oil, phospholipids, waxes and steroidsProportion of oxygen in lipid is lower than carbohydratesLipids (fats and oil)Call as triglyceridesTriglyceride is formed by the condensation of one molecule of glycerol with three molecule of fatty acid

GLYCEROL + (3) FATTY ACID TRIGLYCERIDE + WATER

Lipids (fats and oil)Good stores of energy

Saturated fat : contain saturated fatty acid examples are animal fats, butter, lard

Unsaturated fat : unsaturated fatty acid like vegetable oil, olive oil, sunflower oilLipis (phospholipid)Lipids which have one of its fatty acids replaced by phosphate group.Form main part of the cell membraneand control the permeability of the cell membrane.Lipids (waxes)Long chain moleculepresent on cuticle of the leaf epidermis, seeds, and fruit plants.They are also found in oil glands animal skinCan soften the skinLipids (steroids)Ring like compounds produced in the liver of animal.Example : cholesterol, testostero, oestrogen, progesteronLipids (importance)Energy sourcePhospholipids layer cell membraneSolvent for fat soluble vitamin (A,D,E,K)Protects and insulate the body against low temperatureThe wax in the leaf cuticle prevent water loss through evaporationNUCLEIC ACID

NUCLEIC ACIDEach necleotide made of three parts : a phosphate group, a 5 carbon sugar (pentose) and a nitrogen baseThere are two types of nucleic acid :Deoxyribonucleic acid (DNA) : has 2 chains polynucleotide twisted into double helix. Found in nucleus, chloroplast and mitochondriaRibonucleic acid (RNA) : Short single chain of polynucleotide. Found in cytoplasm, ribosomes, nucleus.Nucleic acid (importance)Store genetic informationDirect syntheis of protein in the cellDetermine the traits that are passed from parents to children.Water (importance)As a universal solventTransport mediumMedium for biochemical reaction in the cellLubricationProviding supportCohesion and high surface tensionMaintaining a constant internal environment