Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Chapter 5 The Structure and Function of Macromolecules
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overview: The Molecules of Life Macromolecules are large molecules composed of thousands of covalently connected atoms
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 5.1: Most macromolecules are polymers, built from monomers A polymer is a long molecule consisting of many similar building blocks called monomers Three of the four classes of life’s organic molecules are polymers: – Carbohydrates – Proteins – Nucleic acids
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Short polymer Unlinked monomer Dehydration removes a water molecule, forming a new bond Dehydration reaction in the synthesis of a polymer Longer polymer Hydrolysis adds a water molecule, breaking a bond Hydrolysis of a polymer The Synthesis and Breakdown of Polymers Dehydration synthesis Hydrolysis Animation: Polymers Animation: Polymers
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Dehydration Synthesis and Hydrolysis
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 5.2: Carbohydrates serve as fuel and building material Carbohydrates include sugars and the polymers of sugars – Monosaccharides – Disaccharides – Polysaccharides
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Sugars Monosaccharides have molecular formulas that are usually multiples of CH 2 O Glucose is the most common monosaccharide
LE 5-3 Triose sugars (C 3 H 6 O 3 ) Glyceraldehyde Aldoses Ketoses Pentose sugars (C 5 H 10 O 5 ) Ribose Hexose sugars (C 5 H 12 O 6 ) Glucose Galactose Dihydroxyacetone Ribulose Fructose
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Linear and ring forms Abbreviated ring structure Monosaccharides serve as a major fuel for cells and as raw material for building molecules – in aqueous solutions they form rings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A disaccharide is formed when a dehydration reaction joins two monosaccharides – glycosidic linkage Animation: Disaccharides Animation: Disaccharides
LE 5-5 Glucose Maltose Fructose Sucrose Glucose Dehydration reaction in the synthesis of maltose Dehydration reaction in the synthesis of sucrose 1–4 glycosidic linkage 1–2 glycosidic linkage
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Polysaccharides Polysaccharides, the polymers of sugars, have storage and structural roles
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings ChloroplastStarch 1 µm Amylose Starch: a plant polysaccharide Amylopectin Storage Polysaccharides Starch, a storage polysaccharide of plants, consists entirely of glucose monomers
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Glycogen is a storage polysaccharide in animals Mitochondria Glycogen granules 0.5 µm Glycogen Glycogen: an animal polysaccharide
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Structural Polysaccharides Cellulose is a major component of the tough wall of plant cells – glycosidic linkages differ from starch The difference is based on two ring forms for glucose: alpha ( ) and beta ( ) Animation: Polysaccharides Animation: Polysaccharides
LE 5-7 a Glucose a and b glucose ring structures b Glucose Starch: 1–4 linkage of a glucose monomers. Cellulose: 1–4 linkage of b glucose monomers.
LE 5-8 Cellulose molecules Cellulose microfibrils in a plant cell wall Cell walls Microfibril Plant cells 0.5 µm Glucose monomer
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Enzymes that digest starch by hydrolyzing alpha linkages can’t hydrolyze beta linkages in cellulose
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Chitin – exoskeleton of arthropods – cell walls of many fungi Chitin can be used as surgical thread
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 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 – no affinity for water (hydrophobic) Fats Phospholipids Steroids
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Fats – constructed from: Glycerol Fatty acids Animation: Fats Animation: Fats
LE 5-11a Dehydration reaction in the synthesis of a fat Glycerol Fatty acid (palmitic acid)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings In a fat, three fatty acids are joined to glycerol by an ester linkage, creating a triacylglycerol, or triglyceride Ester linkage Fat molecule (triacylglycerol)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Saturated fatty acids Unsaturated fatty acids
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Saturated fat and fatty acid. Stearic acid Saturated fats – Most animal fats are saturated (except fish) – solid at room temperature – may contribute to cardiovascular disease through plaque deposits
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Unsaturated fats – Plant fats and fish fats – liquid at room temperature and are called oils Unsaturated fat and fatty acid. Oleic acid cis double bond causes bending
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Phospholipids Phospholipid – two fatty acids and a phosphate group – attached to glycerol Fatty acid tails are hydrophobic Phosphate group are hydrophilic
LE 5-13 Structural formula Space-filling model Phospholipid symbol Hydrophilic head Hydrophobic tails Fatty acids Choline Phosphate Glycerol Hydrophobic tails Hydrophilic head
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Phospholipids self-assemble into a bilayer WATER Hydrophilic head Hydrophobic tails WATER
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 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
Copyright © 2005 Pearson Education, Inc. publishing as 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 – Functions include: Structural support Storage Transport Cellular communications Movement Defense against foreign substances
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Animation: Structural Proteins Animation: Structural Proteins Animation: Storage Proteins Animation: Storage Proteins Animation: Transport Proteins Animation: Transport Proteins Animation: Receptor Proteins Animation: Receptor Proteins Animation: Contractile Proteins Animation: Contractile Proteins Animation: Defensive Proteins Animation: Defensive Proteins Animation: Enzymes Animation: Enzymes Animation: Hormonal Proteins Animation: Hormonal Proteins Animation: Sensory Proteins Animation: Sensory Proteins Animation: Gene Regulatory Proteins Animation: Gene Regulatory Proteins
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Substrate (sucrose) Enzyme (sucrose) Fructose Glucose Enzymes acts as a catalyst, speeding up chemical reactions Enzymes can perform their functions repeatedly
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Amino Acid Monomers Amino acids – differ in their properties due to differing side chains, called R groups Cells use 20 amino acids to make thousands of proteins Amino group Carboxyl group carbon
LE 5-17a Isoleucine (Ile) Methionine (Met) Phenylalanine (Phe) Tryptophan (Trp) Proline (Pro) Leucine (Leu) Valine (Val) Alanine (Ala) Nonpolar Glycine (Gly)
LE 5-17b Asparagine (Asn) Glutamine (Gln)Threonine (Thr) Polar Serine (Ser) Cysteine (Cys) Tyrosine (Tyr)
LE 5-17c Electrically charged Aspartic acid (Asp) Acidic Basic Glutamic acid (Glu) Lysine (Lys)Arginine (Arg) Histidine (His)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Amino Acid Polymers Amino acids are linked by peptide bonds A polypeptide is a polymer of amino acids
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Protein Conformation and Function Functional protein – one or more polypeptides twisted, folded, and coiled into a unique shape – conformation determines function Groove A space-filling model A ribbon model Groove
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Four Levels of Protein Structure Primary structure – unique sequence of amino acids Secondary structure – coils and folds in the polypeptide chain (H bonds) Tertiary structure – interactions among various R groups (various bonds) Quaternary structure – protein consists of multiple polypeptide chains Animation: Protein Structure Introduction Animation: Protein Structure Introduction
LE 5-20 Amino acid subunits pleated sheet + H 3 N Amino end helix
LE 5-20a Amino acid subunits Carboxyl end Amino end Animation: Primary Protein Structure Animation: Primary Protein Structure
LE 5-20b Amino acid subunits pleated sheet helix Animation: Secondary Protein Structure Animation: Secondary Protein Structure
LE 5-20d Hydrophobic interactions and van der Waals interactions Polypeptide backbone Disulfide bridge Ionic bond Hydrogen bond Animation: Tertiary Protein Structure Animation: Tertiary Protein Structure
LE 5-20e Chains Chains Hemoglobin Iron Heme Collagen Polypeptide chain Polypeptide chain Animation: Quaternary Protein Structure Animation: Quaternary Protein Structure
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Sickle-Cell Disease: A Simple Change in Primary Structure A slight change in primary structure can affect a protein’s conformation and ability to function Sickle-cell disease – results from a single amino acid substitution in the protein hemoglobin Red blood cell shape Normal cells are full of individual hemoglobin molecules, each carrying oxygen. 10 µm Red blood cell shape Fibers of abnormal hemoglobin deform cell into sickle shape.
LE 5-21b Primary structure Secondary and tertiary structures Normal hemoglobin Val His Leu 4 Thr 5 Pro 6 Glu 7 Primary structure Secondary and tertiary structures Sickle-cell hemoglobin Val His Leu 4 Thr 5 Pro 6 ValGlu 7 Quaternary structure Normal hemoglobin (top view) Function Molecules do not associate with one another; each carries oxygen. Quaternary structure Sickle-cell hemoglobin Function Molecules interact with one another to crystallize into a fiber; capacity to carry oxygen is greatly reduced. Exposed hydrophobic region subunit
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings What Determines Protein Conformation? In addition to primary structure, physical and chemical conditions can affect conformation Alternations in pH Salt concentration Temperature This loss of a protein’s native conformation is called denaturation
LE 5-22 Denaturation Renaturation Denatured proteinNormal protein
LE 5-23a Chaperonin (fully assembled) Hollow cylinder Cap Chaperonins are protein molecules that assist the proper folding of other proteins
LE 5-23b Polypeptide Correctly folded protein An unfolded poly- peptide enters the cylinder from one end. Steps of Chaperonin Action: The cap comes off, and the properly folded protein is released. The cap attaches, causing the cylinder to change shape in such a way that it creates a hydrophilic environment for the folding of the polypeptide.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 5.5: 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 © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Roles of Nucleic Acids There are two types of nucleic acids: – Deoxyribonucleic acid (DNA) – Ribonucleic acid (RNA) DNA directs: – its own replication – synthesis of messenger RNA (mRNA)
LE 5-25 NUCLEUS DNA CYTOPLASM mRNA Ribosome Amino acids Synthesis of mRNA in the nucleus Movement of mRNA into cytoplasm via nuclear pore Synthesis of protein Polypeptide
LE 5-26a 5 end 3 end Nucleoside Nitrogenous base Phosphate group Nucleotide Polynucleotide, or nucleic acid Pentose sugar Nucleic acids are polymers called polynucleotides
LE 5-26b Nitrogenous bases Pyrimidines Purines Pentose sugars Cytosine C Thymine (in DNA) T Uracil (in RNA) U Adenine A Guanine G Deoxyribose (in DNA) Nucleoside components Ribose (in RNA) There are two families of nitrogenous bases: Pyrimidines have a single six-membered ring Purines have a six- membered ring fused to a five-membered ring
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The DNA Double Helix DNA double helix: – two backbones run in opposite 5´ to 3´ directions an arrangement referred to as antiparallel One DNA molecule includes many genes
LE 5-27 Sugar-phosphate backbone 3 end 5 end Base pair (joined by hydrogen bonding) Old strands Nucleotide about to be added to a new strand 5 end New strands 3 end 5 end 3 end 5 end
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 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