Biomolecules I PDF

ESSENTIAL BIOLOGY STRUCTURES, PROPERTIES, AND FUNCTIONS OF BASIC BIOMOLECULES (PART I) Week 2 Learning Outcomes 2     Explain how a cell make a variety of large molecules from a small set of molecules  Monomers vs Polymers  Condensation vs Hydrolysis Define the carbohydrates macromolecules  m...

ESSENTIAL BIOLOGY STRUCTURES, PROPERTIES, AND FUNCTIONS OF BASIC BIOMOLECULES (PART I) Week 2 Learning Outcomes 2     Explain how a cell make a variety of large molecules from a small set of molecules  Monomers vs Polymers  Condensation vs Hydrolysis Define the carbohydrates macromolecules  monosaccharides, disaccharides & polysaccharides Define the lipid macromolecules  Triglycerides (Fats), phospholipids & steroids Describe their  Chemical structure  Functions Organic Compounds 3     ~25 elements are essential for human life 4 elements make up ~96% of the weight of most living organisms  Oxygen, Carbon, Hydrogen, Nitrogen Trace elements  Essential, but are only needed in minute quantities Unique properties of an organic compound depend on  Size & shape of its carbon skeleton  Groups of atoms attached to that skeleton Testosterone Estradiol @2015 Pearson Education, Inc. Biomolecules 4    Molecule with majority of carbon atoms bonded to other carbon atoms or atoms of oxygen, nitrogen, sulfur, phosphorus, or hydrogen And is can be found in organism Biomolecules can be conceived as hydrocarbons bonded with atoms of oxygen, nitrogen, sulfur, phosphorus, hydrogen, or functional group Biomolecules 5 Common Functional Groups in Biomolecules Raven P. (2016). Biology 11Ed. NY; McGraw Hill Biomolecules 6 Common Functional Groups in Biomolecules Raven P. (2016). Biology 11Ed. NY; McGraw Hill Biomolecules are polymers 7 Raven P. (2016). Biology 11Ed. NY; McGraw Hill Macromolecules are Polymers, Built from Monomers 8    Monomers  Building blocks / repeated units of polymers  Some monomers have other function on their own Polymers  Large molecules consisting of identical / similar building blocks (monomers) linked together  Carbohydrates, proteins & nucleic acids https://upload.wikimedia.org/wikipedia/commons/thumb/2/ 20/Lego_dublo_arto_alanenpaa_5.JPG/1280pxLego_dublo_arto_alanenpaa_5.JPG Macromolecules  Gigantic molecules consisting of thousands of atoms connected covalently  Carbohydrates, lipids, proteins & nucleic acids Dehydration & Hydrolysis 9 Dehydration reaction building a polymer chain Hydrolysis breaking down a polymer @2015 Pearson Education, Inc.   Dehydration reactions (removal of water) & hydrolysis (addition of water) are facilitated by enzymes (specialized macromolecules that speed up chemical reactions in cells) Cells invest energy to carry out dehydration reactions Cells Make Large Molecules from a Limited Set of Small Molecules 10      All living things are made up of 4 main classes of macromolecules  Organic  Carbohydrates – sugars & starch  Lipids  Proteins  Nucleic acids – DNA & RNA Variety in macromolecules accounts for the uniqueness of each organism A cell makes a large number of polymers from a small group of monomers  Proteins are made from only 20 different amino acids  DNA is built from just 4 kinds of monomers (nucleotides) Monomers used to make polymers are essentially universal Key to great diversity of polymers  Arrangement – variation in monomer sequence https://www.virtualhighschool.com/blog/wp-content/uploads/2015/09/Lego.png Properties of Carbon (the foundation of biomolecule) 11 1. 2. 3. 4. 5. The properties of carbon made it become the framework of biomolecules Form four bonds  can form chain (polymers) and bond with different functional groups Form four bonds  allow the existence of stereoisomers Able to form double or triple bond  Allow oxidation (release of energy) Carbon bond has high energy  good fuel molecules Structure of Carbon Bonds 12 Raven P. (2016). Biology 11Ed. NY; McGraw Hill https://www.britannica.com/science/isomerism/Conformational-isomers/media/296365/82 Structural Isomers 13  Same Chemical formula for glucose and fructose: C6H12O6 Glucose Raven P. (2016). Biology 11Ed. NY; McGraw Hill https://www.thepaleomom.com/wp-content/uploads/2015/07/glucose-and-fructose-molecular-structure.jpg Fructose Structural Isomers 14  Structural isomers have the same chemical formula but different skeleton Glucose Fructose Raven P. (2016). Biology 11Ed. NY; McGraw Hill Stereoisomers 15 Stereoisomers have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in space. Raven P. (2016). Biology 11Ed. NY; McGraw Hill Stereoisomers - Enantiomer 16 Chiral molecule Enantiomer pairs Caraway odour Sweet spearmint odour https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Chirality/Chirality_and_Stereoisomers Common monosaccharides 17 Raven P. (2016). Biology 11Ed. NY; McGraw Hill Monosaccharides are the Simplest Carbohydrates 18   Carbohydrates range from small sugar molecules (monomers) to large polysaccharides Sugar monomers are monosaccharides (CH2O)n  e.g. glucose, fructose, galactose C6H12O6 Glucose   Fructose Carbon skeletons of monosaccharides vary in length  3 – 7 carbon atoms Many sugars form rings in aqueous solutions Structural formula Abbreviated structure Simplified structure @2015 Pearson Education, Inc. Monosaccharides are the Simplest Carbohydrates 19  Monosaccharides Cellular functions  Main fuels for cellular work  Raw materials for the synthesis of other organic molecules @2015 Pearson Education, Inc. Two Monosaccharides (Monomers) are Linked to Form a Disaccharide via Dehydration Reaction 20 Covalent bond : glycosidic linkage   Monosaccharides condense (dehydrate) to disaccharides Cellular functions of disaccharides  Sucrose provides a source of energy & raw materials to plants Raven P. (2016). Biology 11Ed. NY; McGraw Hill Polymerisation of Polysaccharides 21   Multiple disaccharides condense (dehydrate) to polysaccharides Cellular functions of disaccharides  Sucrose provides a source of energy & raw materials to plants Polysaccharides are Long Chains of Sugar Units 22  Cellulose Raven P. (2016). Biology 11Ed. NY; McGraw Hill Polysaccharides are Long Chains of Sugar Units 23  Starch and glycogen Polysaccharides are Long Chains of Sugar Units 24     Polysaccharides are macromolecules, polymers composed of thousands of monosaccharides Usually hydrophilic (water-loving) The structure & function of a polysaccharide are determined by  Its sugar monomers  The positions of glycosidic linkages Function as 1. Storage molecules  Starch: energy storage in plants (within chloroplasts & other plastids)  Glycogen: energy storage in animals (in liver & muscles cells) 2. Structural compounds  Cellulose: forms plant cell walls  Chitin: used by insects & crustaceans to build an exoskeleton; found in the cell walls of fungi Structural & Storage Polysaccharides 25 Starch granules in a potato tuber cell Glycogen granules in muscle tissue Amylose – unbranched Amylopectin – somewhat branched Starch Glucose monomer Glycogen – branched Glycogen Cellulose microfibrils in a plant cell wall Cellulose molecules Cellulose – unbranched Cellulose Hydrogen bonds @2015 Pearson Education, Inc. Cellulose 26   Major component of the tough wall of plant cells A polymer of glucose (like starch)  The glycosidic linkages differ (based on 2 ring forms for glucose)  Alpha ()  Beta ()  Polymers with  glucose are helical  Polymers with  glucose are straight   In straight structures, H atoms on one strand can bond with OH groups on other strands Parallel cellulose molecules held together this way are grouped into microfibrils, which form strong building materials for plants @2015 Pearson Education, Inc. Chitin 27     Another structural polysaccharide Found in the exoskeleton of arthropods Also provides structural support for the cell walls of many fungi Similar to cellulose   With  linkages The glucose monomer of chitin has a nitrogen-containing appendage @2015 Pearson Education, Inc. Three Types of Carbohydrates 28 Monosaccharides Disaccharides Polysaccharides  Water-soluble  Water-soluble  Water-insoluble  Sweet-tasted  Sweet-tasted  No sweet taste  Energy production  Transportation  Energy storage  Energy production    Monomers of disaccharides and polysaccharides E.g. glucose, fructose, galactose  E.g. sucrose (glucose + fructose), lactose (glucose + galactose)  Structural molecules E.g. starch, cellulose, glycogen Lipids 29  Water insoluble (hydrophobic, or water-fearing)  Important in long-term energy storage  Contain twice as much energy as a polysaccharide     Consist mainly of carbon & hydrogen atoms  Linked by nonpolar covalent bonds Differ from carbohydrates, proteins & nucleic acids  Not huge molecules  Not built from monomers Lipids vary a great deal in structure & function 3 types of lipids 1. Triglyceride (fats) - acts as energy-reserving molecules 2. Phospholipids - important component of the plasma membrane 3. Steroids - important precursors for sex hormones Fat (Triglyceride) 30   1 glycerol + 3 fatty acids  Glycerol is a 3-carbon alcohol with a hydroxyl (OH) group attached to each carbon  A fatty acid consists of a carboxyl group (COOH) attached to a long carbon skeleton  Joined by an ester linkage, creating a triacylglycerol (triglyceride) Major function @2015 Pearson Education, Inc.  Energy storage  Humans & other mammals store fat in adipose cells  Adipose tissue also cushions vital organs & insulates the body Saturated & Unsaturated Fatty Acids 31   Saturated fatty acids  Fats with the maximum number of hydrogens  No double bonds Glycerol H2O Unsaturated fatty acids  One fewer H atom on each C of the double bond Fatty acid  Double bonds cause kinks / bends in the carbon chain, preventing them from packing together tightly and solidifying at room temperature  Certain unsaturated fatty acids are not synthesized in the human body  Must be supplied in the diet  Essential fatty acids  e.g. omega-3 fatty acids for normal growth, & thought to provide protection against cardiovascular disease @2015 Pearson Education, Inc. Structure of fatty acid 32 9 Last double bond 7 8 5 6 Last methyl group (CH3) as #1 4 3 2 http://tidsskriftet.no/2013/09/trans-fat-can-be-hidden-health-risk 1 Lipids - Fats 33  Which is saturated fat? Lipids – fats 34  Structure and physical properties of fatty acid Good stacking Strong intermolecular force High melting temperature Solid/semi-solid Animal fat Form plaque in blood vessel Poor stacking Weak intermolecular force Low melting temperature Liquid 35 At room temperature, the molecules of an unsaturated fat, e.g. olive oil, cannot pack together closely enough to solidify because of the kinks in some of their fatty & hydrocarbon chains At room temperature, the molecules of a saturated fat, e.g. the fat in butter, are packed closely together, forming a solid @2015 Pearson Education, Inc. Common chemical reactions of fats in food processing – hydrogenation 36  Using hydrogen to turn unsaturated fatty acid to saturated fatty acid or partial saturated fatty acid Not necessarily complete! Also deep fry http://www.indiana.edu/~oso/Fat/trans.html Common chemical reactions of fats in food processing – rancidification 37  Spoilage of unsaturated fat due to oxidation or hydrolysis  Increased by           https://en.wikipedia.org/wiki/Rancidification#/media/File:Lipid_peroxidation.svg Degree of saturation Heat Light Trace metal Oxygen conc. Surface area Antioxidant Vitamin E, BHA, BHT Discolouration Smell Peroxide Key features of fatty acids 38     Most common fatty acid are even numbered having 1420 carbon atoms Most animals fats are saturated; most plant fats are unsaturated Most naturally occurring unsaturated fatty acid is in cis configuration Polyunsaturated fatty acids have a lower melting point than saturated fatty acids Lipids – Fats 39  Example of fatty acids in food  Animal fats    Seed fats    Low in saturated fats Oleic acid, linoleic acid, linolenic acid Coconut and palm oil   70% saturated fats Palmitic acid, stearic acid Short chain fatty acid (SCFA), Lauric acid Marine oil   Low in saturated fat Eicosapentaenoic acid (EPA), Docosahexaenoic acid (DHA) http://thoughtformdesign.com/wp-content/uploads/2015/03/05-information-design.jpg Phospholipids 40    Major component of all cell membranes Structurally similar to fats  Fats contain 3 fatty acids attached to glycerol  Phospholipids contain 2 fatty acids & a phosphate group (-ve charge) are attached to glycerol Phospholipids cluster into a bilayer  Hydrophilic heads (phosphate group & its attachments) are in contact with water of the environment & internal part of the cell  Hydrophobic tails (2 fatty acid tails) cluster together in the center of the bilayer Phosphate group Glycerol Water Hydrophilic heads Hydrophobic tails Symbol for phospholipid Water @2015 Pearson Education, Inc. Structure and function of lipid in cell membrane 41  Membrane structure – lipid bilayer structure hydrophilic hydrophobic hydrophilic Structure and function lipid 42     Hydrophilic heads form hydrogen bond with water The lipid tails point towards each other by the “force” of hydrophobic interaction Hydrophobic interaction is the tendency of a molecule avoiding water The surface area is smallest by pointing toward the tail each other Micelle Steroids & Cholesterol @2015 Pearson Education, Inc. 43  Steroids  Lipids in which the carbon skeleton contains 4 fused rings  Cholesterol  Common component in animal cell membranes  Starting material for making steroids, incl. sex hormones  Essential in animals  High levels in the blood may contribute to cardiovascular disease  Anabolic steroids  Synthetic variants of the male hormone testosterone  Abused by some athletes with serious consequences e.g. violent mood swings, depression, liver damage, cancer, high cholesterol, high blood pressure Lipids – fats, phospholipid, and sterol 44 http://www.eatingdisorderpro.com/2012/03/02/omega-fatty-acids-explained/