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1 Edited by Janet A Renshaw Biological MoleculesCarbohydratesProteinsWaterLipidsSchool ofBiologicalSciencesEdited by Janet A Renshaw
2 Contents Introduction Carbohydrates Proteins Lipids Water Questions and AnswersEXIT
3 IntroductionThe three main organic molecules are carbohydrates, proteins and lipids.These molecules are very important in living organisms, they can be used as building blocks for cells and also for energyThey are all based on the chemical elements carbon, hydrogen and oxygen.Proteins can also contain the elements nitrogen, sulphur and phosphorous
4 Carbohydrates Proteins Lipids The structures of these molecules are of key importance to their functionsWater is a very important molecule, it makes up between % of the body mass of most organisms and without it life on earth would not have evolved.
5 Carbohydrates starches cellulose glycogen sugars carbon hydrogen oxygenCarbohydrate molecules consist of 3 elementsCarbohydrates have roles in all forms of life and make up most of the organic matter on earth.Monosaccharides are the basic monomer units of which carbohydrates are composed.The most common monosaccharide is glucose
6 Glucose Glucose can exist in two forms, the form and the form. The two forms of glucose have the same properties.The only difference between them is the position of one of the OH groups.HOOHHOH2COHHin the form the OH is hereOHin the form the OH is hereHOHThis has a great effect on the property of molecules made when glucose molecules link together.
7 DisaccharidesWhen 2 monosaccharides join together they form a larger disaccharide molecule.Two monosaccharides can become linked by a condensation reaction.DisaccharideMonosaccharideMonosaccharideshareoxygenRemoval of H20The linkage is via a glycosidic bond where they share an oxygen molecule and a water molecule is eliminated.
8 Condensation Reaction between 2 glucose monomers Glycosidic BondH2O
9 Examples of Disaccharides MaltoseFormed from 2 glucose molecules, formed in germinating seeds from the breakdown of starch, providing energySucroseFormed from 1 glucose and 1 fructose molecule and is the form in which carbohydrates are transported in the phloem in plantsLactoseFormed from 1 glucose and 1 galactose molecule, it is an energy source found in the milk of nearly all mammals
10 Polysaccharides glycogen starch cellulose Carbohydrates which are made from many linked monosaccharidemonomers form long chain-like moleculescalled polymers.glycogenstarchpolysaccharidescellulose- made from glucosemonomers
11 Starch Found in two forms, which are both made up of glucose One form is amylose which consists of un-branched chains of glucose,this coils into a helical compact structureThe other form is amylopectin which consists of branched chains of glucose, this forms a branched compact brush.
12 Starch is the main storage carbohydrate in plants. Amylase(enzyme)Breaks downsources ofmaltoseStarchglucoseenergyH2OHydrolysis reaction:- A chemical process whereby a compound is cleaved into two or more simpler compounds along with the uptake of water
13 Glycogen A polymer of glucose monomers. It is the main storage carbohydrate in mammals found in liver and muscle cells.It is more branched in structure than amylopectin.The more branched the molecule, the quicker it can be made and broken.
14 Cellulose Is a polymer of glucose monomers. It is an important componentof plant cell walls.It does not spiral as with glucose glucose consists of chains that are straight and long, they lie parallel to each other bound together by hydrogen bonds.
15 ProteinsProteins have many roles in living organisms and are extremely important. There are many different types of proteins with different functions, for example,Enzymes are proteins which speed up the rate of biological reactionsBiological moleculeBiological moleculewith enzymeBiological moleculewith enzymeBiological moleculewith enzymeEnzymeAntibodies are protective proteins and as part of the immune system they help fight diseaseANTIBODIESDISEASEHaemoglobin is a protein that transports oxygen in the blood.
16 Proteins are polymers made up of monomers called amino acids. There are 20 different amino acids, amino acids can join in any order toproduce an infinite number of different proteins.The only thing that changes between different amino acids is the R groupThe R group can contain hydrogen and/or carbon and sometimes oxygen, sulphur and nitrogen.This is the basic structure of an amino acid.
17 A condensation reaction joins two amino acids together forming a dipeptide. The bond formed between them is called a peptide bondPeptide BondH2OA chain of many amino acids linked by peptide bonds is called a polypeptide. A protein can consist of one or more polypeptides.Proteins can get broken down by hydrolysis reactions into polypeptides, dipeptides and amino acids.
18 Protein StructureThere are four different levels of protein structure.The primary structure :- this is the sequence of amino acids in the polypeptide formed from many condensation reactionsaminoacidaminoacidaminoacidaminoacidaminoacidaminoacidaminoacidaminoacidaminoacidaminoacidH2OH2OH2OH2OH2OH2OH2OH2OH2O
19 The secondary structure :- where the polypeptide chains can fold into stable 3D regular shapes. One secondary structure is the -helixwhere the chains fold into a helical shape. Another structure is the strand-helix structure
20 The tertiary structure :- this is when further folding occurs and this is the overall shape of the polypeptide chain.This 3D shape is maintained by a series of weak interactions which are mostly hydrogen bonds.This is the tertiary structure of the alpha chain of the protein, haemoglobin.
21 Quaternary Structure taken by means of rasmol (www.dkfz-heidelberg.de) The quaternary structure :- polypeptides can associate with other polypeptides and they way in which they bind together to form the molecule is the quaternary structure.Quaternary Structure taken by means of rasmol (www.dkfz-heidelberg.de)
22 Protein SubgroupsProteins fit into two subgroups, globular proteins and fibrous proteins.Globular proteins, for exampleenzymes, form roughly a sphericalshape and most of them are solublein water.SubstrateThe function of a globular protein is determined by its shape, so its shape is vital.Molecular representation of an enzymeThe usual function for this subgroup is a chemical function.
23 Fibrous proteins do not form a spherical structure they form long chains and they are insoluble.Fibrous proteins have structural roles, like giving strength or elasticity tocertain tissues.Muscle Fibre (www.uoguelph.ca)
24 Proteins can become denatured causing their shape to change therefore affecting their function. A protein can vibrate due to an increase in temperature, which can cause it to become denatured, causing the weak bonds holding the tertiary or quaternary structure together to break.Example shows an enzyme becoming denatured and losing hold on a substrate
25 Lipids hydrogen oxygen fats oils steroids waxes Lipid molecules consist of 3 elementscarbonhydrogenoxygenLipids are insoluble.They are important dietary constituents as they are full of energy, contain certain vitamins and have a major role in cell membranes.Unlike carbohydrates and proteins, lipids do not form polymers.Two major types of lipids are triglycerides and phospholipids.
26 This group of lipids are the TriglyceridesThis group of lipids are thefats and oils.They are formed from a glycerol molecule linked by ester bonds to three fatty acids.Ester bond:-This is formed from a condensation reaction where the carboxyl group of a fatty acid and an OH group from the glycerol join and water is lost so they share an oxygen atom.The formula for fatty acids is R-COOH, where the R, which is the hydrocarbon chain can be saturated or unsaturated.
28 Phospholipids Fatty acid glycerol Fatty acid phosphate The phosphate group is soluble in water, it is water loving, which is termed hydrophillic.The fatty acids are insoluble in water, they repel water, which is known as hydrophobic.fatty acidsDue to these propertiesphospholipids form cellmembranes when in waterglycerolglycerolglycerolwaterphosphates
29 Phospholipid Bilayer formed in water Simplified structure of a phospholipid molecule used in diagrams of membranesH2OH2OH2OPhospholipid Bilayer formed in waterH2OH2OH2OH2O
30 Water Water is an inorganic substance. It has many essential properties, it has these properties because of the way in which the molecules in water bond together.The biological importance of water is dependent on itsphysical properties.
31 Some Important Properties of Water Solvent PropertiesWater is a polar molecule and it’s polarity makes it an excellent solventfor other polar molecules.There is a whole range of other polar molecules, whichinclude small organic units such as glucose and aminoacids, also ions like calcium,potassium and sodium.Non-polar substances do not dissolve in water.
32 Specific Heat Capacity Water has a high specific heat capacity,which means it has temperature stability.It takes a large amount of heat (energy)to raise the temperature of watermeasurably. Due to this water containingorganisms are stable thermally.
33 Latent Heat of Evaporation Due to the high specific heat capacity, water resistsevaporation into gas better than other liquids do.This is significant to humans and other animals as werely on the evaporation of water from our body surface asa cooling device.
34 Questions and AnswersThis section is to test your knowledge on what has been covered in this package.You will need paper and a pen to help you answer some of the questionsTo get the answer click on the answer buttonNow go to the next page to start testing your knowledge.
35 Click here to see diagram CARBOHYDRATESQuestion What is the name of thiscarbohydrate monomer ?Click here for answerQuestion 2 Draw a diagram to show how two of these monomers form adisaccharide and label the bondClick here to see diagram
36 Question 3 What is the name of the disaccharide formed ? Click here for answerQuestion What are the two forms of the polysaccharide starch ?Click here for answerQuestion What are the differences between the two forms ?Click here for answer
37 Question 6 What three elements can be found in proteins but not in carbohydrates and lipids ?Click here for answerQuestion 7 There are two subgroups of proteins, globular proteins andfibrous proteins.Which subgroup -a) is soluble in water ?b) has structural roles ?Click here for answersc) form long chains ?d) is spherical in shape ?
38 Question 8 What type of reaction occurs to join amino acids together? Click here for answerQuestion What is the name of the bond formed between amino acidsin a protein ?Click here for answer
39 Question 10 What are the two major types of lipids? Click here for answerQuestion How is an ester bond formed in a triglyceride?Click here for answer
40 Question 12 The phosphate group of a phospholipid is soluble in water, what is the term used for this type of moleculeClick here for answerQuestion Fatty acids are insoluble in water, what is the term used forthis type of molecule?Click here for answer
41 Question 14 Name two important properties of water. Click here for answerQuestion Water is a polar molecule do Non-polar substancesdissolve in water?Click here for answer
42 You have reached the end of this revision package Choose an optionReturn to CarbohydratesReturn to ProteinsReturn to LipidsReturn to WaterReturn to Question and AnswersExit the package
43 Answer This carbohydrate monomer is glucose Q1Answer This carbohydrate monomeris glucose
45 Answer The disaccharide formed is maltose Q3Answer The disaccharide formedis maltose
46 Answer The two forms of starch are amylose and amylopectin Q4Answer The two forms of starch are amylose and amylopectin
47 Q5Answer Amylose consists of unbranched chains of glucose and has a helical compact structureAmylopectin consists of branched chains of glucose and has a branched compact structure
48 Answer Nitrogen, sulphur and phosphorous Q6Answer Nitrogen, sulphur and phosphorous
49 Answer Globular proteins a) soluble in water ? Fibrous proteins Q7AnswerGlobular proteinsa) soluble in water ?Fibrous proteinsb) structural roles ?Fibrous proteinsc) form long chains ?Globular proteinsd) spherical in shape ?
50 Answer A condensation reaction Q8Answer A condensation reaction