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Biological Molecules (Triglycerides (Commonly known as fats and oils. Some…
Biological Molecules
Triglycerides
Commonly known as fats and oils. Some of their functions in the body are; energy storage, protection and insulation.
The chemical elements in them are carbon, hydrogen and oxygen
They are made up of 3 fatty acids and 1 glycerol these are joined together in condensation reactions, which produce 3 water molecules. The chemical bond is an ester bond.
As the trigylcerides are hydrophobic it means they are insoluble so it doesn't affect the water potential, this is why they are suitable as energy storage molecules.
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-A saturated fatty acid has NO C=C double bond
-An unsaturated fatty acid has 1 OR MORE C=C double bond
Monosaccharides
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Glucose is the most common monosaccharides
Fructose is found in fruit
Galactose is found in dairy products
They are joined together by glycosidic bonds in condensation reactions to make disaccharides (Water is also produced)
These two monosaccharides make up these disaccharides:
Alpha-glucose + alpha-glucose = Maltose
Alpha-glucose + galactose = Lactose
Alpha-glucose + fructose = Sucrose
Phospholipids
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It has a hydrophilic head and hydrophobic tail, so it can be used as an emulsifier
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When they are added to water they self assemble into a phospholipid bilayer. The hydrophobic tail faces inwards and the hydrophilic tail faces outwards, towards the water.
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Proteins
Their major functions include; structural, contractile, storage, defence, signalling, transport and enzymes.
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They are long chains of monomers called amino acids. There are 20 different amino acids used in protein each with a similar structure.
A protein is like a necklace of amino acid beads, which often folds up into a ball, there is a huge variety of possible proteins.
Glucose
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Also can be made into a polymer, so then can be made into starch/glycogen
Bonds
Hydrogen- weakest bonds, also hold secondary structure together
Ionic bond- strong bonds between oppositely charged R groups. Broken by heat and pH changes, denaturing protein sometimes reversibly.
Disulfide bridges- strongest bonds between two sulphur atoms in R groups of amino acid cysteine. Only broken by heat, no pH changes, denaturing protein irreversibly
Polypeptide backbone- amino acids are held together by peptide bonds. Their sequence is a proteins primary structure.
Amino acids
The monomers that join together to form a protein are amino acids, all amino acids and proteins contain nitrogen.
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Amino acids link together in long chains through condensation reaction forming peptide bonds with each other forming a polypeptide
A polypeptide is a polymer of amino acids joined together by peptide bonds. A protein consists of one or more polypeptides joined together. When two amino acids join together they form a dipeptide. The H and OH are lost and formed into water.
Protein Structure
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Tertiary- folding into an overall 3D shape (ionic and hydrogen bonds, also disulfide bridges)
Quaternary- more than one polypeptide (ionic and hydrogen bonds, also disulfide bridges)
Polymers
The types of biological molecules which all organisms are made from are similar, this is indirect evidence that they all evolved from a common ancestor, many of these molecules are polymers.
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The three types of polymers are; Proteins, Nucleic acids and Polysaccharides.
Polysaccarides
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Common polysaccharides include; Starch, Cellulose and Glycogen
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Types of Polysaccharides
Cellulose
Cellulose is a polymer of beta-glucose monomers. The monomers have an alternating up-down pattern. This is due to the H and OH groups being inverted in B-glucose.
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Its long, straight and has unbranched chains which line up in parallel to form microfibrills.
Cellulose is strong because the chains are hold together by hydogren bonds. Each bond is weak but many together are strong
Starch
Starch is found in plants, which store glucose within chloroplasts as insoluble starch granules.
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Plants produce glucose by photosynthesis, store it as starch and then hydrolyses it back into glucose for respiration
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Glycogen
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Its also helical, insoluble and large
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Lipids
Are mainly hydrophobic which means that they don't mix well with water, they are NOT POLYMERS
Examples are: Triglycerides, Phospholipids and Cholesterol
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Carbohydrates
Carbohydrates come in 3 main forms; Monosaccharides, Disaccharides and Polysaccharides.
Carbohydrates contains; carbon, oxygen and hydrogen. They are mainly used in the body for energy, either immediately or stored for later use.