Overview of biochemistry

ADVANCED BIOCHEMISTRY Overview of Biochemistry Instructor: Dr Nguyen Thao Trang School of Biotechnology Semester I 2015-2016 Outlines • Macromolecules • Carbohydrates: simple and complex • Proteins: Enzymes • Nucleotides: ATP, NAD+ • Nucleic acids: DNA Macromolecules • All living things are made up of four classes of large biological molecules: – – – – Carbohydrates Lipids Proteins Nucleic acids • Macromolecules are large molecules composed of thousands of covalently connected atoms • Molecular structure and function are inseparable Macromolecules are polymers built from monomers • A polymer is a long molecule consisting of many similar building blocks • These small building-block molecules are called monomers • Three of the four classes of life’s organic molecules are polymers – Carbohydrates – Proteins – Nucleic acids Macromolecules are polymers built from monomers • Many biological molecules formed by linking a chain of monomers Fundamentals of biochemistry-Life at the molecular level, Voet, Voet, Pratt • Synthesis and breakdown of polymers – Synthesis: a dehydration reaction occurs when two monomers bond together through the loss of a water molecule – Breakdown: polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction Macromolecules are polymers built from monomers • Synthesis of a polymer: dehydration reaction Macromolecules are polymers built from monomers • Breakdown of a polymer: hydration reaction (hydrolysis) Outlines • Macromolecules • Carbohydrates: simple and complex • Proteins: Enzymes • Nucleotides: ATP, NAD+ • Nucleic acids: DNA Carbohydrates happyherbivore.com sidrapractice.wordpress.com sciencephoto.com marketplace.yet2.com • Carbohydrates include sugars and the polymers of sugars • The simplest carbohydrates are monosaccharides, or single sugars • Carbohydrate macromolecules are polysaccharides, polymers composed of many sugar building blocks Carbohydrates: function • Rapidly mobilized source of energy – Monosaccharides and disaccharides • Energy storage – Glycogen in animals – Starch in plants • Structural – In cell walls bacteria and plants (Cellulose) – In exoskeletons (Chitin) • Coupled with protein to form glycoproteins – Important in cell membranes 10 Nucleotides • Nucleic acids, the primary players in the storage and decoding of genetic information are polymers called polynucleotides • Each polynucleotide is made of monomers called nucleotides • Functions of nucleotides: – Energy (ATP) – Coenzymes that aid enzyme function (NAD+) – Messengers within cells (GTP) • Nucleotides consists of a sugar, phosphate groups, and a base • Nucleosides consists of a sugar and a base 80 Nucleotides • Sugar: • Base: – There are nucleotide bases: Adenine, Thymine, Uracil, Guanine, Cytosine Fundamentals of biochemistry-Life at the molecular level, Voet, Voet, Pratt 81 Nucleotides Fundamentals of biochemistry-Life at the molecular level, Voet, Voet, Pratt 82 Adenosine triposphate • Adenosine triphosphate (ATP): a nucleotide containing adenine, ribose, and a triphosphate group • ATP is formed from adenosine diphosphate (ADP) in photosynthesis or the breakdown of carbohydrates and fatty acids: Fundamentals of biochemistry-Life at the molecular level, Voet, Voet, Pratt • ATP is known as energy-currency or energy carrier as it provides energy for cellular work by transferring its phosphate groups to another molecule 83 Nicotinamide adenine dinucleotide • Nicotinamide adenine dinucleotide (NAD+): Activated carrier of electrons for the oxidation of fuel molecules Oxidized form Reduced form NAD+ accepts electrons and hydrogen ion , hydrogen ion appears as proton in solvent NAD+, oxidized form Biochemistry, Tymoczko, Berge, Strayer 84 Outlines • Macromolecules • Carbohydrates: simple and complex • Proteins: Enzymes • Nucleotides: ATP, NAD+ • Nucleic acids: DNA 85 Nucleic acid • The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a gene which is made of DNA, a nucleic acid made of monomers called nucleotides • Nucleic acids are chains of nucleotides whose phosphates bridge the 3’ and 5’ positions of neighboring ribose units • The linkage between individual nucleotides is known as a phosphodiester bond, so named because the phosphate is esterified to two ribose units • Each nucleotide that has been incorporated into the polynucleotide is known as a nucleotide residue 86 Nucleic acid There are two types of nucleic acids: • Deoxyribonucleic acid (DNA): the sugar is deoxyribose and the four major bases are adenine (A), thymine (T), cytosine (C), guanine (G) • Ribonucleic acid (RNA): the sugar is ribose and one of the four major bases is uracil (U) instead of T in DNA 87 Nucleic acid 88 Nucleic acid • The sequence of bases along a DNA or messenger RNA (mRNA) polymer is unique for each gene • DNA provides directions for its own replication • DNA directs synthesis of mRNA and, through mRNA, controls protein synthesis • Protein synthesis occurs on ribosome 89 Nucleic acid 90 Nucleic acid 91 Nucleic acid 92 Structures of DNA and RNA • RNA molecules usually exist as single polynucleotides chains • DNA molecules have two polynucleotides spiraling around an imaginary axis, forming a double helix • In the DNA double helix, the two backbones run in opposite 5’→ 3’ directions from each other, an arrangement referred to as antiparallel • The nitrogenous bases in DNA pair up and form hydrogen bonds: A always with T, and G always with C  Called complementary base pairing • Complementary pairing can also occur between two RNA molecules or between parts of the same molecule • In RNA, T is replaced by U so A and U pair 93 Structures of DNA and RNA 94 ... simple sugars • Cyclization of glucose and fructose: Fundamentals of biochemistry- Life at the molecular level, Voet, Voet, Pratt 15 Stereochemistry of carbohydrates Biochemistry: a short course... Polysaccharides are long chains of saccharides (sugars) – 100 sugars to 1000 sugars • Cellulose, starch and glycogen consist of chains of only glucose • Chitin consists of chains of glucose with N-acetyl... things are made up of four classes of large biological molecules: – – – – Carbohydrates Lipids Proteins Nucleic acids • Macromolecules are large molecules composed of thousands of covalently connected