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Biological Molecules - Coggle Diagram
Biological Molecules
Lipids
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Fats vs. Oils
Fats are solid at room temperature, and tend to be from animals
Oils are liquid at room temperature, and tend to be from plants
Importance
Lipids make up about 10% of body mass, and are essential to cell structure, particularly cell membranes, and form energy stores
Structure
Lipids are made from two types of molecule, glycerol, and fatty acids
Glycerol is an oily liquid, and each molecule is joined to three fatty acids
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Carbohydrates
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Structure
Saccharides
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Two monosaccharides joined together forms a disaccharide, like sucrose, made from glucose and fructose
Glucose molecules join together to form polymers such as starch, made from a long chain of glucose molecules, or cellulose
Starch
Starch is a large insoluble molecule, and is the storage carbohydrate in plants (amyl- = starch (amyloplast, amylase)
Importance
Carbohydrates make up about 1% of body mass, but are vital for respiration with the oxidising of glucose
Food Tests
Test for glucose
Benedict's solution is added to the sample dissolved in water, and then warmed. If the solution turns brick red a reducing sugar is present (green = traces, and orange = moderate)
Test for protein
Equal parts potassium hydroxide solution and water are added to a powdered protein, and then a very small amount of copper sulfate solution is added. If protein is present, it will turn purple/lilac. (Sometimes, the two solutions are already mixed and called biuret solution)
Test for starch
Iodine solution is added to a sample. If starch is present, then it will turn blue/black, if not, it will remain orange/brown
Test for lipid
Ethanol is added to the sample, and is shaken to dissolve. This solution is added to cold water, where, if a lipid is present, it should form a white emulsion at the top, while the ethanol dissolves in the water.
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Proteins
Importance
Proteins make up about 18% of body mass, the second largest percentage after water, and are vital to essential compounds, such as enzymes
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Structure
All proteins are comprised of amino acids, of which there are twenty different types
Because there are twenty different amino acids, the order of them and the shape of the protein
Globular vs. Fibrous
Globular proteins are proteins which have a glob-like structure, and tend to be functional
Fibrous proteins are proteins which have a fibrous structure, and tend to be structural
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