Chapter+3+Powerpoint+(Organic+Compounds)+(1).pptx

Carbon and the Molecular Diversity of Life PowerPoint® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Copyright © 2008 Pearson Education, Inc., publishing as Pearson...

Carbon and the Molecular Diversity of Life PowerPoint® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Overview: Carbon: The Backbone of Life Although cells are 70–95% water, the rest consists mostly of carbon-based compounds Carbon is unparalleled in its ability to form large, complex, and diverse molecules Proteins, DNA, carbohydrates, and other molecules that distinguish living matter are all composed of carbon compounds Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 4.1: Organic chemistry is the study of carbon compounds Organic chemistry is the study of compounds that contain carbon Organic compounds range from simple molecules to colossal ones Most organic compounds contain hydrogen atoms in addition to carbon atoms Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  The electron configuration of carbon gives it covalent compatibility with many different elements The valences of carbon and its most frequent partners (hydrogen, oxygen, and nitrogen) are the “building code” that governs the architecture of living molecules Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 4-4 Hydrogen Oxygen Nitrogen Carbon (valence = 1) (valence = 2) (valence = 3) (valence = 4) H O N C Hydrocarbons Hydrocarbons are organic molecules consisting of only carbon and hydrogen Many organic molecules, such as fats, have hydrocarbon components Hydrocarbons can undergo reactions that release a large amount of energy Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 4-6 Fat droplets (stained red) 100 µm (a) Mammalian adipose cells (b) A fat molecule  The Structure and Function of Large Biological Molecules PowerPoint® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Overview: The Molecules of Life All living things are made up of four classes of large biological molecules: carbohydrates, lipids, proteins, and nucleic acids Within cells, small organic molecules are joined together to form larger molecules Macromolecules are large molecules composed of thousands of covalently connected atoms Molecular structure and function are inseparable Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 5.1: 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 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Synthesis and Breakdown of Polymers A deyhydration synthesis (aka condensation) occurs when two monomers bond together through the loss of a water molecule Enzymes are macromolecules that speed up the dehydration process Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-2 HO 1 2 3 H HO H Short polymer Unlinked monomer Dehydration removes a water molecule, forming a new bond H2 O HO 1 2 3 4 H Longer polymer (a) Dehydration reaction in the synthesis of a polymer HO 1 2 3 4 H Hydrolysis adds a water H2O molecule, breaking a bond HO 1 2 3 H HO H (b) Hydrolysis of a polymer The Diversity of Polymers Each cell has thousands of different kinds of macromolecules 2 3 H HO Macromolecules vary among cells of an organism, vary more within a species, and vary even more between species An immense variety of polymers can be built from a small set of monomers Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 5.2: Carbohydrates serve as fuel and building material 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 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Sugars Monosaccharides have molecular formulas that are usually multiples of CH2O Glucose (C6H12O6) is the most common monosaccharide Monosaccharides are classified by – The location of the carbonyl group (as aldose or ketose) – The number of carbons in the carbon skeleton Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-3 Trioses (C3H6O3) Pentoses (C5H10O5) Hexoses (C6H12O6) Aldose s Glyceraldehyde Ribose Glucose Galactose Ketose s Dihydroxyacetone Ribulos e Fructose  A disaccharide is formed when a dehydration reaction joins two monosaccharides This covalent bond is called a glycosidic linkage Animation: Disaccharides Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-5 1–4 glycosidic linkage Glucose Glucose Maltose (a) Dehydration reaction in the synthesis of maltose 1–2 glycosidic linkage Glucose Fructose Sucrose (b) Dehydration reaction in the synthesis of sucrose Polysaccharides Polysaccharides, the polymers of sugars, have storage and structural roles The structure and function of a polysaccharide are determined by its sugar monomers and the positions of glycosidic linkages Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Storage Polysaccharides Starch, a storage polysaccharide of plants, consists entirely of glucose monomers Plants store surplus starch as granules within chloroplasts and other plastids Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-6 Chloroplast Starch Mitochondria Glycogen granules 0.5 µm 1 µm Amylose Glycogen Amylopecti n (a) Starch: a plant (b) Glycogen: an animal polysaccharide polysaccharide  Glycogen is a storage polysaccharide in animals Humans and other vertebrates store glycogen mainly in liver and muscle cells Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Structural Polysaccharides The polysaccharide cellulose is a major component of the tough wall of plant cells Like starch, cellulose is a polymer of glucose, but the glycosidic linkages differ The difference is based on two ring forms for glucose: alpha (α) and beta (β) Animation: Polysaccharides Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-7 (a) α and β glucose ring structures α Glucose β Glucose (b) Starch: 1–4 linkage of α glucose monomers (b) Cellulose: 1–4 linkage of β glucose monomers Fig. 5-8 Cell walls Cellulose microfibrils in a plant cell wall Microfibril 10 µm 0.5 µm Cellulose molecule s β Glucose monomer  Chitin, another structural polysaccharide, is found in the exoskeleton of arthropods Chitin also provides structural support for the cell walls of many fungi Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-10 (a) The structure (b Chitin forms the (c) Chitin is used to make of the chitin ) exoskeleton of a strong and flexible monomer. arthropods. surgical thread. Concept 5.3: Lipids are a diverse group of hydrophobic molecules Lipids are the one class of large biological molecules that do not form polymers The unifying feature of lipids is having little or no affinity for water Lipids are hydrophobic because they consist mostly of hydrocarbons, which form nonpolar covalent bonds The most biologically important lipids are fats, phospholipids, and steroids Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fats Fats are constructed from two types of smaller molecules: glycerol and fatty acids Glycerol is a three-carbon alcohol with a hydroxyl group attached to each carbon A fatty acid consists of a carboxyl group attached to a long carbon skeleton Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-11 Fatty acid (palmitic acid) Glycerol (a) Dehydration reaction in the synthesis of a fat Ester linkage (b) Fat molecule (triacylglycerol)  Fatty acids vary in length (number of carbons) and in the number and locations of double bonds Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds Unsaturated fatty acids have one or more double bonds Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-12 Structural formula of a saturated fat molecule Stearic acid, a saturated fatty acid (a) Saturated fat Structural formula of an unsaturated fat molecule Oleic acid, an unsaturated fatty acid cis double bond causes (b) Unsaturated fat bending Phospholipids In a phospholipid, two fatty acids and a phosphate group are attached to glycerol The two fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-13 Hydrophilic head Choline Phosphate Glycerol Hydrophobic tails Fatty acids Hydrophilic head Hydrophobic tails (a) Structural formula (b) Space-filling model (c) Phospholipid symbol Fig. 5-14 Hydrophilic WATER head Hydrophobic WATER tail Steroids Steroids are lipids characterized by a carbon skeleton consisting of four fused rings Cholesterol, an important steroid, is a component in animal cell membranes Although cholesterol is essential in animals, high levels in the blood may contribute to cardiovascular disease Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 5.4: Proteins have many structures, resulting in a wide range of functions Proteins account for more than 50% of the dry mass of most cells Protein functions include structural support, storage, transport, cellular communications, movement, and defense against foreign substances Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Table 5-1  Enzymes are a type of protein that acts as a catalyst to speed up chemical reactions Enzymes can perform their functions repeatedly, functioning as workhorses that carry out the processes of life Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-16 Substrate (sucrose) Glucose Enzyme (sucrase OH ) H2O Fructos e HO Polypeptides Polypeptides are polymers built from the same set of 20 amino acids A protein consists of one or more polypeptides Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Amino Acid Monomers Amino acids are organic molecules with carboxyl and amino groups Amino acids differ in their properties due to differing side chains, called R groups Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-UN1 α carbon Amino Carboxyl group group Fig. 5-17a Nonpolar Glycine Alanine Valine Leucine Isoleucin (Gly or (Ala or A) (Val or V) (Leu or e G) L) (Ile or I) Methionin Phenylalanin Tryptopha Proline e e n (Pro or (Met or (Phe or F) (Trp or W) P) M) Fig. 5-17b Polar Serine Threonine Cysteine Tyrosine Asparagin Glutamin (Ser or (Thr or T) (Cys or C) (Tyr or Y) e e S) (Asn or N) (Gln or Q) Fig. 5-17c Electrically charged Acidi Basi c c Aspartic Glutamic Lysine Arginine Histidine acid acid (Lys or (Arg or R) (His or H) (Asp or D) (Glu or E) K) Amino Acid Polymers Amino acids are linked by peptide bonds A polypeptide is a polymer of amino acids Polypeptides range in length from a few to more than a thousand monomers Each polypeptide has a unique linear sequence of amino acids Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-18 Peptide bond (a) Side chains Peptide bond Backbone Amino end Carboxyl end (b) (N-terminus) (C-terminus) Protein Structure and Function A functional protein consists of one or more polypeptides twisted, folded, and coiled into a unique shape Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-19 Groov e Groov e (a A ribbon model of (b A space-filling model of ) lysozyme ) lysozyme  The sequence of amino acids determines a protein’s three-dimensional structure A protein’s structure determines its function Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-20 Antibody protein Protein from flu virus Four Levels of Protein Structure The primary structure of a protein is its unique sequence of amino acids Secondary structure, found in most proteins, consists of coils and folds in the polypeptide chain Tertiary structure is determined by interactions among various side chains (R groups) Quaternary structure results when a protein consists of multiple polypeptide chains Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Primary structure, the sequence of amino acids in a protein, is like the order of letters in a long word Primary structure is determined by inherited genetic information Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-21 Primary Secondary Tertiary Quaternary Structure Structure Structure Structure β pleated sheet H3 N + Amino end Examples of amino acid subunits α helix Fig. 5-21a Primary Structure 1 5 + H3N Amino end 10 15 Amino acid subunits 20 25  The coils and folds of secondary structure result from hydrogen bonds between repeating constituents of the polypeptide backbone Typical secondary structures are a coil called an α helix and a folded structure called a β pleated sheet Animation: Secondary Protein Structure Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-21c Secondary Structure β pleated sheet Examples of amino acid subunits α helix  Tertiary structure is determined by interactions between R groups, rather than interactions between backbone constituents These interactions between R groups include hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals interactions Strong covalent bonds called disulfide bridges may reinforce the protein’s structure Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-21e Tertiary Structure Quaternary Structure Fig. 5-21f Hydrophobic interactions and van der Waals interactions Polypeptide backbone Hydrogen bond Disulfide bridge Ionic bond  Quaternary structure results when two or more polypeptide chains form one macromolecule Collagen is a fibrous protein consisting of three polypeptides coiled like a rope Hemoglobin is a globular protein consisting of four polypeptides: two alpha and two beta chains Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-21g Polypeptid β Chains e chain Iron Heme α Chains Hemoglobin Collagen Sickle-Cell Disease: A Change in Primary Structure A slight change in primary structure can affect a protein’s structure and ability to function Sickle-cell disease, an inherited blood disorder, results from a single amino acid substitution in the protein hemoglobin Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-22 Normal hemoglobin Sickle-cell hemoglobin Val His Le Thr Pr Gl Gl Primary Primary Val His Le Thr Pr Val Gl u o u u structure structure 1 2 3 4 5 6 7 1 2 u3 4 o5 6 u7 Exposed Secondary Secondary hydrophobi and tertiary β and tertiary c β structures subunit structures region subunit β α α β Quaternary Normal Quaternary Sickle-cell structure hemoglobin structure hemoglobin (top view) α β β α Function Molecules do Function Molecules not associate interact with with one one another and another; each crystallize into carries oxygen. a fiber; capacity to carry oxygen is greatly reduced. 10 µm 10 µm Red blood Normal red Red blood Fibers of abnormal cell shape blood cell shape hemoglobin deform cells are full of red blood cell into individual sickle shape. hemoglobin moledules, each carrying oxygen. What Determines Protein Structure? In addition to primary structure, physical and chemical conditions can affect structure Alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein to unravel This loss of a protein’s native structure is called denaturation A denatured protein is biologically inactive Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-23 Denaturatio n Normal protein Renaturation Denatured protein Nucleic acids store and transmit hereditary information The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a gene Genes are made of DNA, a nucleic acid Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Roles of Nucleic Acids There are two types of nucleic acids: – Deoxyribonucleic acid (DNA) – Ribonucleic acid (RNA) DNA provides directions for its own replication DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis Protein synthesis occurs in ribosomes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-26-3 DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM mRNA 2 Movement of mRNA into Ribosome cytoplasm via nuclear pore 3 Synthesis of protein Amin Polypeptide o acids The Structure of Nucleic Acids Nucleic acids are polymers called polynucleotides Each polynucleotide is made of monomers called nucleotides Each nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphate group The portion of a nucleotide without the phosphate group is called a nucleoside Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-27 5′ end Nitrogenous bases Pyrimidines 5′C 3′C Nucleoside Nitrogenous base Cytosine Thymine (T, in DNA) Uracil (U, in RNA) (C) Purines Phosphate group Sugar 5′C (pentose) Adenine (A) Guanine 3′C (b) Nucleotide (G) Sugars 3′ end (a) Polynucleotide, or nucleic acid Deoxyribose (in DNA) Ribose (in RNA) (c) Nucleoside components: sugars Nucleotide Monomers Nucleoside = nitrogenous base + sugar There are two families of nitrogenous bases: – Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring – Purines (adenine and guanine) have a six- membered ring fused to a five-membered ring In DNA, the sugar is deoxyribose; in RNA, the sugar is ribose Nucleotide = nucleoside + phosphate group Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Nucleotide Polymers Nucleotide polymers are linked together to build a polynucleotide Adjacent nucleotides are joined by covalent bonds that form between the –OH group on the 3′ carbon of one nucleotide and the phosphate on the 5′ carbon on the next These links create a backbone of sugar- phosphate units with nitrogenous bases as appendages The sequence of bases along a DNA or mRNA polymer is unique for each gene Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The DNA Double Helix A DNA molecule has 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 One DNA molecule includes many genes The nitrogenous bases in DNA pair up and form hydrogen bonds: adenine (A) always with thymine (T), and guanine (G) always with cytosine (C) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-28 5' end 3' end Sugar-phosphate backbones Base pair (joined by hydrogen bonding) Old strands Nucleotide about to be added to a new strand 3' end 5' end New strands 3' end 5' end 5' end 3' end DNA and Proteins as Tape Measures of Evolution The linear sequences of nucleotides in DNA molecules are passed from parents to offspring Two closely related species are more similar in DNA than are more distantly related species Molecular biology can be used to assess evolutionary kinship Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Theme of Emergent Properties in the Chemistry of Life: A Review Higher levels of organization result in the emergence of new properties Organization is the key to the chemistry of life Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-UN2