2. Macromolecule in Biochemistry.pdf
- 1. Biochem-700 3(3-0) CONCEPTS OF BIOCHEMISTRY Dr Saba Chaudhry (PhD Biochemistry)
- 2. Macromolecules Monomers + functional groups Four types of macromolecules of interest to us: Carbohydrates Proteins Lipids Nucleic Acids
- 3. Carbohydrates Monomer: simple sugar eg. Glucose Functional group(s): Carbonyl Hydroxyl Polymer: complex CHO Starch, glycogen
- 4. Structure of monosaccharide Fisher projection • The straight chain structural formula Haworth projection • Cyclic formula or ring structure X-ray diffraction analysis • Boat and chair form
- 5. A. MONOSACCHARIDES •Aldoses • monosaccharides containing an aldehyde group
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- 10. A. MONOSACCHARIDES • Ketoses • monosaccharides containing a ketone group
- 11. DISACCHARIDES These are glycosides formed by the condensation of 2 simple sugars. If the glycosidic linkage involves the carbonyl groups of both sugars ( ) the resulting disaccharide is On the other hand, if the glycosidic linkage involves the carbonyl group of only one of the 2 sugars (as in maltose and lactose) the resulting disaccharide is reducing.
- 14. Reducing versus none reducing sugar
- 15. POLYSACCHARIDES These are formed by the condensation of n molecules of monosaccharides with the removal of n-1 molecules of water. Since condensation involves the carbonyl groups of the sugars, leaving only one free carbonyl group at the end of a big molecule, polysaccharides are non-reducing. They are of 2 types: 1. Homopolysaccharides (e.g. Starch, Glycogen, cellulose). 2. Heteropolysaccharides (e.g. glycosaminoglycans, glycoproteins)
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- 19. Aldehyde group H-C=O Monosaccharides Enantiomers Mirror images of each other Disaccharides sucrose = glucose + fructose Lactose = galactose + glucose Maltose= glucose + glucose Oligosaccharides Polysaccharides Homo- Starch, glycogen, cellulose Hetero- GAGs Epimers Differ in configuration around one specific carbon atom Isomers Same chemial formula Ketoses Keto group C=O Aldoses glycolipids have an important role in the immune response.
- 20. Functions of Carbohydrates ➢ Carbohydrates are the most abundant organic molecules in nature. ❖ Providea significant fraction of the dietarycalories for most organisms ❖ Act as a storage form of energy in the body, ❖ serve as cell membrane components that mediate some forms of intercellularcommunication. ❖ Carbohydrates also serve as a structural component of many organisms, including the cell walls of bacteria, the exoskeleton of many insects, and the fibrous cellulose of plants. ❖ Ribose and deoxyribose in nucleic acids; Galactose in lactose of milk, in glycolipids, and in combination withprotein in glycoproteins and proteoglycans. ❖ Diseases associated with carbohydrate metabolism include diabetes mellitus, galactosemia, glycogen storage diseases, and lactose intolerance
- 21. Proteins Monomer: amino acids 20 total, 9 to 10 essential Functional group(s): Carboxyl Amino Polymer Polypeptide Protein
- 22. Protein Structure The 20 amino acids are joined together by peptide bonds. The linear sequence contains the information necessary to generate a protein molecule with a unique three- dimensional shape. The complexity of protein structure is best analyzed by considering the molecule in terms of four organizational levels, namely, primary, secondary, tertiary, and quaternary
- 23. Primary structure The sequence of amino acids in a protein The AA sequence must be written from the N-terminus to the C-terminus. Many genetic diseases result in proteins with abnormal amino acid sequences, (Sickle cell anemia, Glu replaced with Val)
- 24. Peptide bond Peptide bonds are responsible for maintaining the primary structure Linkage of many amino acids through peptide bonds results in an unbranched chain called a polypeptide
- 25. SECONDARY STRUCTURE OF PROTEINS Regular arrangements of amino acids that are located near to each other in the linear sequence. The R group has an impact on the likelihood of secondary structure formation The α-helix, β-sheet, and β-bend (β-turn) are examples of secondary structures
- 26. Tertiary Structure The configuration of all the atoms in the protein chain: side chains prosthetic groups helical and pleated sheet regions
- 27. Tertiary Structure Protein folding attractions: 1. Non covalent forces a. Inter and intrachain H bonding b. Hydrophobic interactions c. Electrostatic attractions (+ to - ionic attraction) d. Complex formation with metal ions e. Ion-dipole 2. Covalent disulfide bridges A protein domain is a conserved part of a given protein sequence and(tertiary) structure that can evolve, function, and exist independently of the rest of the protein chain
- 29. Quaternary structure is the result of non covalent interactions between two or more protein chains. Oligomers are multisubunit proteins with all or some identical subunits. The subunits are called protomers. two subunits are called dimers four subunits are called tetramers Quaternary structure
- 30. 3 0 Lipids Lipids are bio-molecules that are: • Hydrophobic in nature because of the high amountof Hydrocarbons in their structure • Relatively insoluble in waterbut readily soluble in non- polar solvents such as Chloroform, Benzene and Ether • Easily separatedfrom other biological materials by extraction into organic solvents because of their hydrophobic properties • Examples of lipids: • Fats, Oils, Steroids, Waxes, Fat-soluble Vitamins (Vitamins A, D, E and K), LIPIDS
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- 32. Monomer: Fatty acid Functional group(s): Carboxyl Polymers: many – depending on the type of lipid Phospholipid LIPIDS
- 33. 3 3 What are fatty acids? Aliphatic Carboxylic Acids containing Long Hydrocarbon chains that may be Saturatedor Unsaturated, Fattyacid has both Hydrophobic and Hydrophilic properties, thus are Amphipathic in nature, • Non-polar Hydrophobic Hydrocarbon Chain (Tail) • Polar (-COOH) group (Hydrophilic Head) Examples of fattyacids: Palmitic Acid, Oleic Acid, Arachidonic Acid, Linoleic Acid, Linolenic Acid, etc.
- 34. Nucleic Acids Nucleic acids are: • molecules that store information for cellular growth and reproduction. • deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). • large molecules consisting of long chains of monomers called nucleotides. 34
- 35. Nucleic Acids The nucleic acids DNA and RNA consist of monomers called nucleotides that consist of a • pentose sugar. • nitrogen-containing base. • phosphate. Nucleotide
- 36. Nitrogen Bases The nitrogen bases in DNA and RNA are • pyrimidines C, T, and U. • purines A and G. 36
- 37. Pentose Sugars The pentose (five-carbon) sugar • in RNA is ribose. • in DNA is deoxyribose with no O atom on carbon 2’. • has carbon atoms numbered withprimes to distinguish them from the atoms in nitrogen bases. 37
- 38. Names of Nucleosides and Nucleotides 38
- 39. Primary Structure of Nucleic Acids In the primary structure of nucleic acids • nucleotides are joined by phosphodiester bonds. • the 3’-OH group of the sugar in one nucleotide forms an ester bond to the phosphate group on the 5’-carbon of the sugar of the next nucleotide. 39
- 40. Primary Structure of Nucleic Acids 40
- 41. Structure of Nucleic Acids A nucleic acid • has a free 5’-phosphate group at one end and a free 3’-OH group at the other end. • is read from the free 5’-end using the letters of the bases. • This example reads —A—C—G—T—. 41
- 42. Compaction of DNA in a eukaryotic chromosome