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Lecture3BIO115Winter11d2l - BIO115 The Molecules of Life...

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Unformatted text preview: BIO115 The Molecules of Life Jessica Pamment Overview • • Importance of carbon Chemical groups essential to life • Biomolecules i. Carbohydrates ii. Lipids iii. Proteins iv. Nucleic Acids Properties of Carbon • The capacity to form multiple bonds and chains at low energies makes life possible • Each carbon atom can bond with as many as four atoms, allowing the formation of chains and rings Carbon Methane, the simplest hydrocarbon hydrocarbon Hydrocarbons as fuel Valences of Major Elements of Organic Compounds Hydrogen (valence = 1) H Oxygen (valence = 2) O Nitrogen (valence = 3) N Carbon (valence = 4) C Variation in Organic Molecules • Length of carbon chain • Orientation of atoms within the molecules • Functional group binding to carbon chain Variation in Carbon Skeletons Ethane (a) Length Propane 1-Butene (c) Double bonds 2-Butene Butane (b) Branching 2-Methylpropane (commonly called isobutane) Cyclohexane (d) Rings Benzene Chemical Groups • Different chemical groups can affect the properties of organic compounds by: 1. Affecting molecular structure 1. Affecting chemical reactivity Common Functional Groups Common Functional Groups Biomolecules • Carbohydrates, proteins and nucleic acids are macromolecules and polymers • Polymers are long molecules consisting of covalently bonded monomers • Lipids are not true polymers or macromolecules • Basis for diversity in polymers is arrangement of units HO 1 2 3 H HO H Unlinked monomer H2O HO 1 2 Polymer 3 4 H (a) Dehydration reaction in the synthesis of a polymer HO 1 2 3 4 H Hydrolysis adds a water molecule, breaking a bond H2O HO 1 2 3 H HO H (b) Hydrolysis of a polymer Carbohydrates Carbohydrates • Literally means hydrated carbon • Sugars (monosaccharides and disaccharides) • Polymers of sugars (polysaccharides) Monosaccharides (simple sugars) • • • Can’t be broken down by hydrolysis into smaller sugars Glucose, our most important energy source If it’s an ­ose it is a sugar! MonosacchaMonosaccharide isomers High-fructose corn syrup processed to extract Starch broken down into Glucose converted to sweeter Fructose added to foods as high-fructose corn syrup Ingredients: carbonated water, high-fructose corn syrup, caramel color, phosphoric acid, natural flavors The Ring Structure of Glucose The Ring Structure of Glucose Disaccharides Disaccharides • Double sugar • Constructed from monosaccharides by dehydration reaction • Most common disaccharide: sucrose (glucose + fructose) • Lactose (glucose + galactose) Disaccharide Disaccharide Formation Polysaccharides • Polymers with up to 1000s of monosaccharides joined by covalent bonds • Functions: i. Fuel storage, e.g. starch ii. Structural, e.g. cellulose Polysaccharides Polysaccharides Structural Polysaccharides: cellulose • The most abundant organic compound on Earth • A polymer of glucose monomers • Can’t be broken down by most animals; it is the fiber in our food Prokaryotes in Grazing Animals break down Cellulose Prokaryotes in Grazing Animals break down Cellulose Lipids • • • 1. 2. 3. Not big enough to be considered macromolecules They show hydrophobic (‘water fearing’) behavior Three most important types in biology: Fats Phospholipids Steroids The Synthesis and Structure of a fat, or triglyceride The Synthesis and Structure of a fat, or triglyceride Saturated Fat Stearic acid, a saturated fatty acid (a) Saturated fat Unsaturated Fat Oleic acid, an unsaturated fatty acid cis double bond causes bending (b) Unsaturated fat TYPES OF FATS Saturated Fats Unsaturated Fats Margarine INGREDIENTS: SOYBEAN OIL, FULLY HYDROGENATED COTTONSEED OIL, PARTIALLY HYDROGENATED COTTONSEED OIL AND SOYBEAN OILS, MONO AND DIGLYCERIDES, TBHO AND CITRIC ACID °ANTIOXIDANTS Plant oils Trans fats Omega-3 fats http://bantransfats.com/ Role of Fats 1. Energy storage • Weight for weight, fats provide twice as much energy as glucose • Stored in adipose cells 2. Protection of vital organs 3. Insulation Steroids • Steroids are hydrophobic just like other lipids, but… • Very different from fats in structure and function Steroids • Characterized by four fused rings • Examples include hormones, cholesterol Steroids Steroids Anabolic Steroids • Synthetic variants of testosterone • Mimic effect of testosterone • Side effects: sterility, mood swings, liver damage • Most athletic organizations ban their use Anabolic Steroids and the modern athlete Jose Canseco Marion Jones THG Proteins • Account for more than 50% of dry mass of most cells • Essential for almost every biological function • • • • • Functions include: Enzymes Storage proteins Contractile proteins Antibodies MAJOR TYPES OF PROTEINS Structural Proteins Storage Proteins Contractile Proteins Transport Proteins Enzymes Protein Structure and Function • A protein is a chain of monomers (polypeptide) that has been folded into a 3­D structure • Protein function is determined by its structure • There are four levels of protein structure Amino Acids Acids Joining Joining amino acids Protein Variety Protein Variety • Made possible due to arrangement of amino acids • 20 amino acids • Each polypeptide is at least 100 amino acids • The primary structure defines the specific order of amino acids The primary The primary structure of a protein Protein Shape Protein Shape • A polypeptide is NOT a protein • A protein is a polypeptide that has folded into a 3D structure The four levels of The four levels of protein structure Requirements for Protein Folding • Specific amino acid sequence • Correct pH, temperature, and other environmental factors Denaturation and Renaturation of a Protein Denaturation Normal protein Renaturation Denatured protein Nucleic Acids • Store and transmit hereditary information • Macromolecules that exist as polynucleotide polymers • Two types: DNA: Deoxyribonucleic acid • RNA: Ribonucleic acid Building a Protein Building a Protein DNA 1 mRNA NUCLEUS CYTOPLASM mRNA 2 Ribosome 3 Polypeptide Amino acids DNA Nucleotide DNA The nitrogenous bases of DNA DNA The structure of DNA of An RNA nucleotide nucleotide DNA vs. RNA DNA vs. RNA • Sugar: deoxyribose in DNA, ribose in RNA • Bases: RNA uses Uracil where DNA uses Thymine • RNA is usually single­stranded, DNA is double­stranded THE DOUBLE HELIX 5′ end Hydrogen bond 1 nm 3.4 nm 3′ end 3′ end 0.34 nm (a) Key features of DNA structure (b) Partial chemical structure 5′ end (c) Space-filling model Comparing the amino acid sequence of a protein among six vertebrates vertebrates Summary • Organic compounds are the building blocks of life • Carbon’s properties due to ability to form four covalent bonds • Carbohydrates, proteins, and nucleic acid are polymers of repeating units • Lipid components vary, so not polymers Summary • Carbohydrates play role in fuel storage and structure • Proteins play wide range of roles • Nucleic acids play role storing hereditary information • Lipids play a role as fuel storage, organ protection, insulation ...
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