Essay on Lipids and Carbohydrates
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Lipids and Carbohydrates
Lipids are a group of substances, which include fats, oils and waxes. Carbohydrates include sugars, starches, glycogen and cellulose. They are stored in plants as starches and in animals as glycogen.
There are many differences between carbohydrates and lipids. For example lipids are insoluble in water whereas carbohydrates are soluble in water. This is because lipids contain non - polar hydrocarbon units whereas water contains polar hydrocarbon units. So when the two are mixed together there is no attraction between particles so no breakdown is possible. But lipids care soluble in non - polar solvents, e.g. alcohol. Carbohydrates have polar hydroxyl groups, so there…show more content…
B. Using examples to illustrate your answer, describe the functions of lipids in organism.
Lipids are a useful energy source. They are also an energy store, since they are insoluble in water and have a high energy content it makes them ideal for storage. This energy store is used make up for heat, movement and energy lost by respiration. This energy store is also useful in plants (e.g. sunflower) because it is needed for seed dispersion. Lipids can also be used as insulation. Fat insulates the body because it conducts heat slowly. This type of energy store can be seen with polar bears, for example. They have a thick layer of fat beneath their skin for insulation. Some mammals, e.g. whales or penguins, don't have fur like polar bears do so they need extra insulation called 'blubber' because there is no fur there to trap air and to insulate further. The insulating feature of lipids also protects internal organs. Lipids also store energy useful for hibernation. Phospholipids are the major components in cell membranes; they are ideal for this due to their ability to be permeable with some substances but impermeable to others. Oils and waxes prevent evaporation through the skin or through the leaves of plants. Another important function of lipids is that
Show MoreStructure and Biological Significance of Lipids
Lipids are made up of a wide variety of molecules, but they all contain carbon, hydrogen and oxygen, with a much higher percentage of carbon and hydrogen molecules than oxygen.
There are three kinds of lipids in living organisms: triglycerides, phospholipids and steroids (hormones).
Triglycerides are made up of a glycerol molecule, with three fatty acid chains attached by ester linkages. Glycerol is an alcohol containing 3 carbon atoms. The fact it is an alcohol means it has an -OH group at one end. Fatty acids are hydrocarbon chains, with a -COOH group at one end. This -COOH group reacts with the -OH group of glycerol, and a condensation…show more content…
Unsaturated has at least one carbon double bond, and so could potentially have more hydrogen. Monounsaturated fatty acids have just one carbon double bond, whereas polyunsaturated fats have 2 or more.
Triglycerides with unsaturated fatty acids (or with relatively long fatty acid chains) have a higher melting point, and so are solids at room temperature. These are known as fats, whereas saturated fatty acids (or with relatively short fatty acid chains) are known as oils and are liquids at room temperature. Plants generally produce oils such as olive or corn oil, and animals produce fats such as butter and lard, but there are exceptions to the rule.
The functions of triglycerides are multiple. The main use is as an energy source; they can be broken down and oxidised in respiration, and the energy produced used to make ATP. They can also be used as an energy store, as 1g of fat has twice the energy of 1g of starch or protein so more energy can be stored in a smaller space, so fat stores are lighter and smaller. As well as this, it is insoluble, so it doesn't affect osmotic potential, so it doesn't enter cell's cytoplasm. It is stored in adipose tissue in animals, and plant seeds. The adipose tissue also works as an insulator in artic animals, as fat is a bad conductor of heat, and it has a low density so it is