3.1 Organic Molecules

Transcription

1 Essentials of Biology Sylvia S. Mader 3.1 rganic Molecules rganic hemistry hemistry of living world rganic molecules contain carbon and hydrogen. Inorganic molecules do not ( 2 ) hapter 3 Lecture utline opyright The McGraw-ill ompanies, Inc. ermission required for reproduction or display. Figure 3.1 rganic molecules as structural material opyright The McGraw-ill ompanies, Inc. ermission required for reproduction or display. Figure 3.2 ydrocarbons are highly versatile opyright The McGraw-ill ompanies, Inc. ermission required for reproduction or display. arbon chains can vary in length, and/or have double bonds, and/or be branched. c. 38,000 a. b. a: Lary Lefever/Grant eilman hotography; b: hotodisc/getty F; c:. ol/i SL/hoto esearchers, Inc. arbon chains can form rings of different sizes and have double bonds. arbon atom Total of six electrons 4 in outer shell Almost always shares electrons with S to complete outer shell an bond with as many as 4 other elements Most often shares electrons with other carbon atoms ydrocarbons chains of carbon atoms bonded only to hydrogen atoms Isomers same number and kinds of atoms in a variety of arrangements May have different properties rganic molecules differ in 1. Size and shape of carbon skeleton or backbone 2. Functional group specific combination of bonded atoms that always has the same chemical properties and always reacts the same way eactivity of organic molecule largely dependent on attached functional groups ften use to stand for the rest of the molecule 1

2 Functional Groups Groups ydroxyl arboxyl Amino Sulfhydryl Structure Found In Alcohols, sugars Amino acids, fatty acids Amino acids, proteins S Amino acids cysteine, proteins Figure 3.3 Functional groups 3.2 The Biological Molecules of ells 4 categories arbohydrates Lipids roteins nucleic acids hosphate AT nucleic acids = remainder of molecule Figure 3.4 arbohydrates Figure 3.5 Lipid foods opyright The McGraw-ill ompanies, Inc. ermission required for reproduction or display. opyright The McGraw-ill ompanies, Inc. ermission required for reproduction or display. Bread heese otato orn Ice cream il Lard ice Butter asta Figures 3.6 rotein foods opyright The McGraw-ill ompanies, Inc. ermission required for reproduction or display. Meat Eggs Milk Monomers build polymers! Monomers subunits olymer monomers joined Dehydration reaction Joins monomers to form polymers Equivalent of removing water molecule Tofu Beans uts The McGraw-ill ompanies, Inc./John Thoeming, photographer 2

3 monomer Figure 3.7 Synthesis of a polymer monomer monomer ydrolysis eaction Breaks polymers apart into monomers (digestion) Water is used to break the bond. dehydration reaction polymer a.) Dehydration synthesis reaction Figure 3.7b Digestion of a polymer polymer 2 2 hydrolysis reaction monomer monomer monomer arbohydrates Almost universally used as immediate energy source in living things lay structural roles in cells olymers of monomers called saccharide or sugars Monosaccharide, disaccharide, polysaccharide b.) ydrolysis reaction Monosaccharides Single sugar molecule Simple sugars 3-7 carbon backbone Glucose isomers fructose and galactose Figure 3.8 Glucose ells use glucose as energy source of choice a. b. ibose and deoxyribose found in A and DA ibose: Deoxyribose: c. d. 3

4 Disaccharides 2 monosaccharides bonded together Maltose yeast breaks down maltose in beer for energy and produces ethyl alcohol. Fermentation Sucrose table sugar Lactose milk sugar Figure 3.9 Breakdown of maltose, a disaccharide ole of Maltase? maltose ydrolysis 2 yeast glucose Fermentation olysaccharides olymers of monosaccharides Some function as energy storage molecules. lants store glucose as starch. Animals store glucose as glycogen. Some function as structural components. ellulose plant cell walls Most abundant of all organic molecules Digested only by some microbes hitin crab, lobster, insect exoskeletons Figure 3.10 Starch and glycogen structure and function starch granule in potato cell nonbranched branched 57 a. Starch structure Figure 3.10 continued Figure 3.10 continued glycogen granules in liver cell cellulose fibers in plant cell wall bond 20 c. ellulose structure highly branched 59,400 b. Glycogen structure 4

5 Lipids All are insoluble in water. Due to long nonpolar hydrocarbon chains few hydrophilic functional groups Very diverse structures and functions Fats and oils used for long term energy storage and insulation il may help waterproof skin, hair, and feathers. Figure 3.11 reening in birds Fats and oils Triglyceride composed of 1 glycerol and 3 fatty acids Figure 3.12 Synthesis and breakdown of fat Glycerol dehydration reaction Fatty acids hydrolysis reaction Fat (triglyceride) 3 waters Fatty acids are either Saturated no double bonds between carbon atoms Butter is solid at room temperature. Unsaturated one or more double bonds between carbon atoms ils liquid at room temperature Trans fatty acids have been artificially hydrogenated to make them more solid. Figure 3.13 Fatty acids canola oil carboxyl group bend caused by double bond a. leic acid, a monounsaturated fatty acid (one double bond) found in canola oil. 5

6 Figure 3.13 continued Figure 3.13 continued butter donut carboxyl group b. Stearic acid, a saturated fatty acid (no double bonds) found in butter. carboxyl group c. Elaidic acid, a trans fatty acid (one double bond) found in many snack foods. hospholipids Form bulk of plasma membrane ne end of molecule water-soluble olar phosphate head ther end of molecule not water-soluble onpolar fatty acid tails polar head nonpolar tails phosphate group glycerol fatty acids Figure 3.14 hospholipids from membranes a. hospholipid structure inside of cell outside of cell b. lasma membrane of a cell Steroids Lipids made of four fused rings o fatty acids but are insoluble in water Derived from cholesterol Differ only in functional groups Steroids Lipids made of four fused rings o fatty acids but are insoluble in water Derived from cholesterol Differ only in functional groups Figure 3.15 Steroid diversity a. holesterol 3 3 b. Testosterone 3 c. Estrogen 6

7 Anabolic Steroids Synthetic anabolic steroids are controversial. They are variants of testosterone. Some athletes use anabolic steroids to build up their muscles quickly. pose serious health risks Figure 3.16 Types of proteins Structural proteins roteins Many functions: support, metabolism (enzymes), transport, defense, regulation, and motion Transport proteins ontractile proteins roteins composed of amino acid monomers entral carbon bonded to hydrogen atom, amino group, carboxyl group, and a side chain, or group 20 different amino acids Differ according to group Figure 3.17 Amino acids a. amino group group Amino acid carboxyl group valine (Val) (nonpolar) glutamate (Glu) (ionized) 2 2 tryptophan (Trp) (nonpolar) 2 2 S cysteine (ys) (nonpolar) b. eptides eptide bond formed by dehydration reaction between 2 amino acid monomers eptide 2 or more amino acids covalently linked olypeptide chain of many amino acids joined by peptide bonds Amino acid sequence determines final three-dimensional shape of protein. rotein shape determines its? Figure 3.18 Synthesis and degradation of peptide dehydration reaction hydrolysis reaction Amino acid Amino acid Dipeptide peptide bond eptides eptide bond formed by dehydration reaction between 2 amino acid monomers eptide 2 or more amino acids covalently linked olypeptide chain of many amino acids joined by peptide bonds rotein chain of more than 100 amino acids Structure determines function Amino acid sequence determines the three-dimensional shape of protein. rotein shape determines its? 2 Water 7

8 rotein Shape roteins have four levels of structure. rotein Structure Introduction rimary rotein Structure Secondary rotein Structure Tertiary rotein Structure Quaternary rotein Structure opyright 2007 earson Education Inc., publishing as earson Benjamin ummings Shape of proteins Function determined by three-dimensional shape Denature loss of structure and function A change in p or temperature may denature a protein Four Levels of rotein Structure rimary structure amino acid sequence Under genetic control hanges in DA may affect primary structure Secondary structure portions of chain form helices or pleated sheets. Tertiary structure overall three-dimensional shape of interacting secondary structures Quaternary structure more than one polypeptide chain interacting Figure 3.19 Levels of protein organization rimary structure: sequence of amino acids A change in the primary structure of a protein affects its ability to function. hanging one amino acid in hemoglobin causes sickle-cell disease. nly one small change (mutation) in the hemoglobin gene leads to the production of sickle-cell hemoglobin protein Figure 3.19 (cont.) Secondary structure: alpha helix and pleated sheet Figure 3.19 continued alpha helix hydrogen bond (red) pleated sheet globular shape Quaternary structure: more than one polypeptide Tertiary structure: overall 3-D shape 8

9 Four levels of rotein Structure 1. rimary Structure 2. Secondary Structure 3. Tertiary Structure What Determines the rimary Structure of rotein? The order of in a gene determines the primary structure of a protein Gene: segment of DA that codes for the production of a DA is a nucleic acid Let s learn about nucleic acids 4. Quaternary Structure Figure 3.24 ucleic Acids ucleic acids are information storage molecules. They provide the directions for building proteins. The genetic instructions in DA Must be translated from nucleic acid language to protein language. There are two types of nucleic acids: DA, deoxyribonucleic acid A, ribonucleic acid Figure 3.20 DA and A are polymers of ucleotides phosphate 5' 4' S 3' 2' sugar 1' nitrogencontaining base Each DA nucleotide has one of the following bases: Adenine (A) Guanine (G) Thymine (T) ytosine () ucleotide: phosphate sugar itrogen base 9

10 itrogen Bases in DA: A, T, G, ucleotide monomers are linked into long chains. These chains are called polynucleotides, or DA strands. A sugar-phosphate backbone joins them together. DA and A Structure Figure 3.20 DA structure with base pairs: G with and A with T DA Structure Sugar:????? Bases:????? G T A A G T Guanine (G) Adenine (A) ydrogen bond (red) ytosine () 3 Thymine (T) (DA only) Double elix: Two strands of DA join together omplementary base pairing Adenine (A) with ytosine () with Genetic information stored in sequence of _?? DA Structure Sugar: Deoxyribose Bases: A, T, G, Double elix: Two strands of DA join together omplementary base pairing Adenine (A) with thymine (T) ytosine () with guanine (G) Genetic information stored in sequence of bases A Structure ibonucleic Acid Single strand of A nucleotides Sugar: ribose Bases: A, U, G, Uracil (U) instead of thymine (T) A ucleotide 10

11 Figure 3.20 continued elationship between proteins and nucleic acids A structure with bases G, U, A, Sequence of 1 in DA determines sequence of 2 in a protein. G U bases Sequence of 3 determines proteins structure and 4. Sugar hosphate Backbone A Uracil (U) (A only) Small changes in the DA may cause large changes in the 5 the DA codes for. Sickle cell disease Individual s red blood cells are sickle-shaped. ne amino acid difference Inherited disease elationship between proteins and nucleic acids Figure 3.21 Sickle cell disease Sequence of bases (or nucleotides) in DA determines sequence of amino acids in a protein. normal red blood cells Sequence of amino acids determines proteins structure and function. Small changes in the DA may cause large changes in the protein the DA codes for. Sickle cell disease Individual s red blood cells are sickle-shaped. ne amino acid difference 2 Val is Leu Thr ro Glu Glu ormal hemoglobin 2 Val is Leu Thr ro Val Glu Sickle cell hemoglobin sickled red blood cell Inherited disease Eye of Science/hoto esearchers, Inc. Evolution onnection: DA and roteins as Evolutionary Tape Measures Evolutionary relationships between organisms can be assessed. DA and roteins as Evolutionary Tape Measures ompare nucleotide sequences in DA and amino acid sequences in proteins 11

12 5.2 AT: Energy for ells Figure 5.4 The AT cycle Adenosine triphosphate Energy currency for cells ells use AT to carry out nearly all activities 3 phosphate groups makes it unstable Easily loses a phosphate group to become AD (adenosine diphosphate) ontinual cycle of breakdown and regeneration Figure 5.3 AT energy released during cellular respiration opyright The McGraw-ill ompanies, Inc. ermission required for reproduction or display. AD + AT energy for cellular work (e.g., protein synthesis, muscle contraction) AT releases energy quickly Amount of energy released is usually just enough for a biological purpose Breakdown can be easily coupled to an energyrequiring reaction lease note that due to differing operating systems, some animations will not appear until the presentation is viewed in resentation Mode (Slide Show view). You may see blank slides in the ormal or Slide Sorter views. All animations will appear after viewing in resentation Mode and playing each animation. Most animations will require the latest version of the Flash layer, which is available at 12