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Biochemistry tutorials return to notes Dr. Lisa's Chem site BIOCHEMISTRY: CARBOHYDRATES, PROTEINS, DNA & LIPIDS BIOCHEMICAL MOLECULES CARBOHYDRATES PROTEINS NUCLEIC ACIDS LIPIDS A SIMPLE SUGAR OR POLYMER COMPOSED OF SIMPLE SUGARS A POLYMER COMPOSED OF AMINO ACIDS A POLYMER COMPOSED OF A SUGAR, AN ORGANIC BASE & PHOSPHATE A FAT, OIL, WAX PHOSPHOLIPID OR STEROID CARBOHYDRATES: function: major source of short term energy from our diet foods: breads, fruits, vegetables Monosaccharides- simple sugars Monosaccharides contain 3-6 carbons: 3 C's triose, 4 C's tetrose, 5 C's pentose, 6 C's hexose aldoses - a monosaccharide with an aldehyde group & several hydroxyl groups (glucose, galactose) ketoses - a monosaccharide with a ketone group & several hydroxyl groups (fructose) CHIRALITY AND D,L DESIGNATION Chiral C - a carbon that has 4 different groups attached Chiral compound - a compound containing a chiral C • Chiral compounds have mirror images D, L tells which of the 2 optical isomers we are referring to • If the OH group on the next to bottom C points to the right, it is the D isomer; if it points to the left it is the L isomer • D isomer is usually the one found in nature Monosaccharides with 5 or 6 carbons usually exist in a cyclic form. The OH group on C-5 reacts with the aldehyde or ketone carbonyl group. Disaccharides - 2 or more monosaccharides held together by glycosidic bond SUGAR o SUGAR maltose: Malt sugar contains 2 glucose units lactose: Milk sugar contains galactose and glucose sucrose: Cane sugar contains fructose and glucose Polysaccharides- hundreds or thousands of monosaccharides bonded together glycogen - animals use glycogen as reserve supply of glucose starch (mixture of amylose & amylopectic) - plants store food as starch cellulose - plants use cellulose for structural parts PROTEINS a large polypeptide containing hundreds- thousands of amino acids Functions of different proteins: Enzymes, transporters of molecules & ions, messengers, antibodies, storage, body regulators (e.g. growth), structural support (e.g. hair, muscle tissue, bone, collagen). foods: meat, fish, poultry, cheese and milk products amino acid has amine group and carboxylic acid group (20 amino acids) amino acids are linked to one another via an amide bond amino acid O || CNH amino acid 8 amino acids are essential to diet (not synthesized in body) LIPIDS: FATS, OILS, WAXES OR STEROIDS function: used for long term storage of food - gives off 2-3 times as much energy as carbohydrates, biological membranes, steroids • lipids are not water soluble foods: vegetable oils, margarine, animal fat, milk products fatty acid is carboxylic acid with a long hydrocarbon chain glycerol: HO-CH2CHCH2-OH | OH triglyceride is a fat or oil in which an ester is formed from glycerol and 3 fatty acids g l y c e r o l fatty acid fatty acid fatty acid animal fat contains mostly saturated fatty acids vegetable oil contains mostly unsaturated fatty acids phospholipid contains glycerol, fatty acid, phosphate and amino alcohol wax: fatty acid combined with long chain alcohol steroid: contains four 4 fused carbon rings e.g. chlosterol NUCLEIC ACIDS - DNA, RNA function: store and direct information for cellular growth and reproduction DNA - contains all information needed for development of living system RNA - carries genetic information from DNA to the ribosomes. • Both are polymers of nucleotide units DNA - several million nucleotides; RNA - several thousand nucleotide units • nucleotide contains phosphate group, 5 C sugar and organic base Obase | O=P-O-CH2 | sugar O- base can be adenine, guanine, cytosine, thymine, uracil sugar is ribose or deoxyribose BIOCHEMICAL WEBLINKS Carbohydrates - PP presentation by Timberlake Introduction to Biochemistry - Logan Structures & Functions of sugars, lipids & DNA - MIT hyper textbook Carbohydrates, lipids, proteins & nucleic acids - PP presentations by Hardy at U of Akron Amino Acid Anatomy - John Kyrk at Sirius Images of biological molecules - U of Kansas