Lipids And Nucleic Acids PDF

LIPIDS AND NUCLEIC ACIDS  Lipids Lipids are organic substances that include fats and fat-like substances, such as phospholipid, wax, steroid and sphingolipid. Regardless of their structure they have large amount of C-H bonds (hydrocarbon chains), that all lipids share com...

LIPIDS AND NUCLEIC ACIDS  Lipids Lipids are organic substances that include fats and fat-like substances, such as phospholipid, wax, steroid and sphingolipid. Regardless of their structure they have large amount of C-H bonds (hydrocarbon chains), that all lipids share common features that enable them to be grouped together. Main Elements of Lipids are: 1.Carbon 2.Hydrogen 3.Oxygen Some Lipids contain molecules of other elements such as: 1. Phosphorus 2. Sulfur 3. Nitrogen  Major Categories of Lipids 0 Phospolipids Major component of cell membranes, aid in fat 1 digestion 0 Waxes Water resistance Categorie and protection. s of 2 Lipids 0 Steroid Hormonal signalling cell response to the environment 3 s and growth. 0 Triglyceride Energy storage, thermal insulation and s carrier of fat- soluble 4 vitamins.  Fat and Oils Triglyceride- a fat or oil consisting of one molecule of glycerol bonded to three fatty acids. Glycerol- 3 carbon chain bonded to hydrogen atoms and alcohol groups. Fatty acid- along hydrocarbon chain with a carboxyl group on one end.  There are two types of fatty acids: Saturated fats  Saturated fatty acid- a fatty acid in which all carbon atoms are bonded to other carbon and hydrogen atoms.  Solid at room temperature.  There are two types of fatty acids: Unsaturated fats  Unsaturated fatty acid- a fatty acid in which some carbons are bonded via double bonds to other carbon atoms. Double bond create kinks in the molecule.  Liquid at room temperature. Phospholipid Composed of fatty acid chains attached to a glycerol backbone. The cell membrane is divided into two: the head and the tail. They are amphipathic. Steroids Small lipids where the hydrocarbon backbone has been linked into four rings with various functional groups attached to the rings. The most important steroids in human are cholesterol. Cholesterol helps provide structure to cell membranes and Is a component of bile, which helps in the digestion of dietary fats. Waxes Component for many organisms , such as cuticle covering the surface of leaves and stems of plants and protective coverings on the skin and fur of some animals.  Lipids in living organisms have the following - Solvent for fat solublefunctions: vitamins and hormones. - Prevent water loos from skin surface. The thin layer of oil secreted by sebaceous glands in the skin prevent water evaporation. - Essential parts of cell structures such as cell membranes. Phospholipids are major building blocks of the phospholipids layer of cell membranes. -Insulating material to prevent heat loss and protection against extreme cold. Aquatic animals like whales, have thick layer of fats beneath the skin that helps retain body heat. -Source and storage of energy. As a result of larger hydrogen content of fat a greater degree of oxidation (removal of hydrogen) is required thus, more energy per molecule of fat is obtained compared to carbohydrates. Lipids provide twice as much energy  Nucleic Acids Nucleic Acids- are organic compounds that function for the storage of genetic information which transmitted from one generation to the next offspring. Nucleic Acids function in protein synthesis, as they carry the code needed in the information of specific proteins. The two main types of Nucleic acids: Deoxyribonucleic acid (DNA)- double stranded helix. Ribonucleic acid (RNA) is single stranded structure. Elements of the Nucleic Acids 1.Nitrogen 2.Oxygen 3.Carbon 4.Phosphorous 5.Hydrogen DNA vs RNA  Nucleic Acids Nucleic acids are polynucleotides that is, long chainlike molecules composed of a series of nearly identical building blocks called nucleotides. Nucleotides  Nucleic Acids Nucleic Acids contains four of five possible nitrogen-containing bases: adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U).  NITROGENOUS BASES Four different types of nitrogenous bases are found in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G). In RNA, the thymine is replaced by uracil (U). The chemical structures of A, G, C, T, and U are shown in (Fig. 1.5A). Because of their structural similarity, we usually refer the nine-member double rings adenine and guanine as purines, and six- member single-ring thymine, uracil, and cytosine are pyrimidines.