- consist of Amylose and Amylopectin.
- Amylose is an unbranched polymer and as the chain length increases, the molecules spirals which makes it more compact.
- Composed of 200 to 5000 glucose molecules-a macromolecule.
- Glucose can only be released by enzymes working at each end of the amylose molecule.
- The glucose molecules joined by a 1,4 glycosidic bond. As a result of this structure, amylose releases energy slowly.
- Amylopectin: a polymer of glucose molecules, but it is branched.
- The branching chains have a lot of terminals that can be broken off quickly when energy is needed.
- forms a 1,4 glycosidic bond as well as a few 1,6 glycosidic bond.
- Uses: acts as an energy source. The sugar produced in plants are quickly converted into starch by a condensation reaction. Can be broken down by hydrolysis when plant requires energy.
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- have a lot of side branches which can be broken down quickly which makes it an ideal energy site for active tissue e.g. muscle and liver.
- more 1,6 glycosidic bonds as well a 1,4 glycosidic bons between the glucose molecules.
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Importance of Lipids
- can fulfill protective functions e.g fats around kidneys.
- Important for water proofing furs and feathers.
- Insects and plants use is as an wax for waterproofing their outer surface.
- Good insulators- fatty sheaths insulate nerves so electrical impulses travel faster.
- Insulate animals against heat loss and has a very low density which helps animals to float.
- are insoluble in water, they don't interfere with many water base reactions.
- an important source of energy for animals as they are more effective because they contain more energy per grams than cahbohydrates.
- Plants and animals convert spare energy into fats and oils.
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- another group of macronutrients
- Organic chemicals which contain carbon, hydrogen and oxygen, but fats have a lower proportion of oxygen than cahbohydrates.
- Fats and oils are chemically the same, but fats are solid at room temperature and oils are liquids.
- Insoluble in water so are described as hydrophobic, but dissolve in organic solvent e.g. ethanol.
- Made up of two organic chemicals: fatty acids and glycerol. Lipids are triglycerides as they contain three fatty acids and a glycerol. Glycerol formula C2H8O3.
- Triglycerides formed by a condensation reaction where water is removed between fatty acids and glycerol.
- Chains or tails usually 16-18 chains long although they may contain any number from 14 to 22 carbon atoms. Enzymes responsible for the condensation reaction.
- Hydrophobic properties due to the hydrocarbon tail on the fatty acids and the molecule is large, but small compared to a polymer macromolecule e.g starch.
- Triglycerides clump together into huge gobules in the prescence of water which makes them appar to be macromolecules.
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Continuation of Lipids
- Fatty acids differ in the length and the carbon chain or they could be saturated or unsaturated.
- Saturated fatty acids: is when each carbon atom is joined by a single bond.
- A unsaturated fatty acids: is when the carbon atoms has one or more double bond in the molecule which means that the bonds have more pairs of electrons compared to one.
- A polyunsaturated fatty acids is has more thn one double bond and monounsaturated is when they only have one.
- An ester bond is formed between the glycerol and fatty acids and it specially occurs betwene the hydroxl group and the carboxyl group on the fatty acid. Process called esterification.
- Lipids containing saturated fatty acids are more likely to be solid whereas lipids containing unsaturated fatty acids are more likely to be a liquid.
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- still contains a glycerol and fatty acid, but the phospholipids only contain two fatty acids and have a phosphate group attached.
- An alchol is usually bonded to the phosphate group which affects the properties of phospholipids.
- The head of the phosphate is attracted to the water which is hydrophillic and the tail is hydrophobic. A molecules with a hydrophillic part and hydrophobic part is called amphipathetic.
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1. Ethanol is added to a sample and shaken.
2. If it's a lipid then it will dissolve in the ethanol.
3. Water is added to the mixture and if its a lipid then a white cloudly emulsion will form.
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- Are organic molecules and contain carbon, hydrogen, oxygen and nitrogen.
- They may contai sulphur, phosphorus and other elements.
- Proteins made up of small monomers called amino acids. The amino acids comined by a long chain to produce a protein in a condensation reaction.
- Amino acids has an amine group (NH2) on one side, a carboxyl group (COOH) and a R group. The R group varies between amino acids and it affects the way the amino acids bond with other proteins which depends largely whether the R group is polar or not.
- When condensation reaction occur, a molecule of water is lost and they form a peptide link. When two amino acids join, a dipeptide is formed. Hydrolysis break up the amino acids.
- When its two or more peptide joined together is called a polypeptide chain. When polypeptide chain is folded or coiled or associalted with another polypetide chain, it forms a protein.
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Bonds involved in Proteins
- The bonds are weaker than peptides bond and the bond depends on the atoms in the R group.
- Hydrogen bond: there is a negative charge on the oxygen of the carboxyl group and there's a slight positive charge on the hydrogen in the amine group. When they are close enough, the opposie charges are attracted to each other which result in a hydrogen bond. They are weak, but can be formed when any two amino acids are positioned correctly next to each other. Hydrogen bonds are easily broken and are reformed if the PH and temperature condition change.
- Sulphur Bond: these occur as a result of 2 containing R groups forming a strong covalent bond. An oxidation reaction occurs where resulting in them being stronger than hydrogen bonds, but are less frequent.
- Ionic Bond: occur between a strong positive amine group and a strongly negative amine group and they are buried deep within the protein. They are strong bond, but not as common as other bonds.
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Structure of Protein
- Primary Structure: is the order and the sequence of amino acids in its molecule. Peptide bonds are the only bonds involved in this level of structure. The order of amino acids in the polypeptide chains are controlled by coded instructions stored in the DNA of chromosomes.
- Secondary Structure: this develops when parts of the polypeptide chain take a particular shape straight after being formed at the ribosomes. Some parts become folded ot twisted which results in two types of 3-D structure: alpha helix and beta pleated sheet.
- Tertiary Structure: it is a complex 3-D structure formed when helix and sheet is twisted and folded around itself and the shame is made permanently by four different types of bonding established between adjacent parts of the chain.
- Quarternery Structure: when two or more proteins become held together forming a complex biologically active molecule and some can contain more than one polypeptide chain. The way in which they are linked is quarternery.
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