Biology: Biological Macromolecules and Lipids PDF

BIOLOGY TENTH EDITION Global Edition Campbell Reece Urry Cain Wasserman Minorsky Jackson 5 Biological Macromolecules and Lipid...

BIOLOGY TENTH EDITION Global Edition Campbell Reece Urry Cain Wasserman Minorsky Jackson 5 Biological Macromolecules and Lipids Lecture Presentation by Nicole Tunbridge and Kathleen Fitzpatrick © 2015 Pearson Education, Inc. The Molecules of Life a) All living things are made up of four classes of large biological molecules: carbohydrates, lipids, proteins, and nucleic acids b) Macromolecules are large molecules and are complex c) Large biological molecules have unique properties that arise from the orderly arrangement of their atoms © 2015 Pearson Education Ltd Figure 5.1 © 2015 Pearson Education Ltd Concept 5.1: Macromolecules are polymers, built from monomers a) A polymer is a long molecule consisting of many similar building blocks b) The repeating units that serve as building blocks are called monomers c) Three of the four classes of life’s organic molecules are polymers a)Carbohydrates b)Proteins c)Nucleic acids © 2015 Pearson Education Ltd The Synthesis and Breakdown of Polymers a) Enzymes are specialized macromolecules that speed up chemical reactions such as those that make or break down polymers b) A dehydration reaction occurs when two monomers bond together through the loss of a water molecule c) Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction © 2015 Pearson Education Ltd Figure 5.2 (a) Dehydration reaction: synthesizing a polymer 1 2 3 Short polymer Unlinked monomer Dehydration removes a water molecule, forming a new bond. H2O 1 2 3 4 Longer polymer (b) Hydrolysis: breaking down a polymer 1 2 3 4 Hydrolysis adds a water H2O molecule, breaking a bond. 1 2 3 © 2015 Pearson Education Ltd Concept 5.2: Carbohydrates serve as fuel and building material a) Carbohydrates include sugars and the polymers of sugars b) The simplest carbohydrates are monosaccharides, or simple sugars c) Carbohydrate macromolecules are polysaccharides, polymers composed of many sugar building blocks © 2015 Pearson Education Ltd Sugars a) Monosaccharides have molecular formulas that are usually multiples of CH2O b) Glucose (C6H12O6) is the most common monosaccharide c) Monosaccharides are classified by a)The location of the carbonyl group (as aldose or ketose) b)The number of carbons in the carbon skeleton © 2015 Pearson Education Ltd Figure 5.3 Aldoses (Aldehyde Sugars) Ketoses (Ketone Sugars) Trioses: 3-carbon sugars (C3H6O3) Glyceraldehyde Dihydroxyacetone Pentoses: 5-carbon sugars (C5H10O5) Ribose Ribulose Hexoses: 6-carbon sugars (C6H12O6) Glucose Galactose Fructose © 2015 Pearson Education Ltd  a) Monosaccharides serve as a major fuel for cells and as raw material for building molecules © 2015 Pearson Education Ltd  a) A disaccharide is formed when a dehydration reaction joins two monosaccharides b) This covalent bond is called a glycosidic linkage © 2015 Pearson Education Ltd Figure 5.5 (a) Dehydration reaction in the synthesis of maltose 1−4 glycosidic linkage H2O Glucose Glucose Maltose (b) Dehydration reaction in the synthesis of sucrose 1−2 glycosidic linkage H2O Glucose Fructose Sucrose © 2015 Pearson Education Ltd Polysaccharides a) Polysaccharides, the polymers of sugars, have storage and structural roles b) The architecture and function of a polysaccharide are determined by its sugar monomers and the positions of its glycosidic linkages © 2015 Pearson Education Ltd Storage Polysaccharides a) Starch, a storage polysaccharide of plants, consists entirely of glucose monomers b) Plants store surplus starch as granules within chloroplasts and other plastids c) The simplest form of starch is amylose © 2015 Pearson Education Ltd Figure 5.6 Storage structures (plastids) containing starch granules in a potato Amylose (unbranched) tuber cell Amylopectin Glucose (somewhat monomer branched) 50 µm (a) Starch Glycogen granules in muscle tissue Glycogen (branched) Cell wall 1 µm (b) Glycogen Cellulose microfibrils in a plant cell wall Cellulose molecule (unbranched) Plant cell, 10 µm surrounded by cell wall Microfibril Hydrogen bonds 0.5 µm (c) Cellulose © 2015 Pearson Education Ltd  a) Glycogen is a storage polysaccharide in animals b) Glycogen is stored mainly in liver and muscle cells c) Hydrolysis of glycogen in these cells releases glucose when the demand for sugar increases © 2015 Pearson Education Ltd Structural Polysaccharides a) The polysaccharide cellulose is a major component of the tough wall of plant cells b) Like starch, cellulose is a polymer of glucose, but the glycosidic linkages differ c) The difference is based on two ring forms for glucose: alpha () and beta () © 2015 Pearson Education Ltd Figure 5.7 𝛂 Glucose 𝛃 Glucose (a) 𝛂 and 𝛃 glucose ring structures (b) Starch: 1–4 linkage of 𝛂 glucose monomer (c) Cellulose: 1–4 linkage of 𝛃 glucose monomers © 2015 Pearson Education Ltd  a)Starch ( configuration) is largely helical b)Cellulose molecules ( configuration) are straight and unbranched © 2015 Pearson Education Ltd  a) Enzymes that digest starch by hydrolyzing  linkages can’t hydrolyze  linkages in cellulose b) The cellulose in human food passes through the digestive tract as “insoluble fiber” c) Some microbes use enzymes to digest cellulose d) Many herbivores, from cows to termites, have symbiotic relationships with these microbes © 2015 Pearson Education Ltd  a) Chitin, another structural polysaccharide, is found in the exoskeleton of arthropods b) Chitin also provides structural support for the cell walls of many fungi © 2015 Pearson Education Ltd Figure 5.8 ► The structure of the chitin monomer ► Chitin, embedded in proteins, forms the exoskeleton of arthropods. ► Chitin is used to make a strong and flexible surgical thread. © 2015 Pearson Education Ltd Figure 5.8c Chitin is used to make a strong and flexible surgical thread. © 2015 Pearson Education Ltd Concept 5.3: Lipids are a diverse group of hydrophobic molecules a) Lipids are the one class of large biological molecules that does not include true polymers b) The unifying feature of lipids is that they mix poorly, if at all, with water c) Lipids are hydrophobic becausethey consist mostly of hydrocarbons, which form nonpolar covalent bonds d) The most biologically important lipids are fats, phospholipids, and steroids © 2015 Pearson Education Ltd Fats a) Fats are constructed from two types of smaller molecules: glycerol and fatty acids b) Glycerol is a three-carbon alcohol with a hydroxyl group attached to each carbon c) A fatty acid consists of a carboxyl group attached to a long carbon skeleton © 2015 Pearson Education Ltd Figure 5.9 H2O Fatty acid (in this case, palmitic acid) Glycerol (a) One of three dehydration reactions in the synthesis of a fat Ester linkage (b) Fat molecule (triacylglycerol) © 2015 Pearson Education Ltd  a)In a fat, three fatty acids are joined to glycerol by an ester linkage, creating a triacylglycerol, or triglyceride © 2015 Pearson Education Ltd Figure 5.9b Ester linkage (b) Fat molecule (triacylglycerol) © 2015 Pearson Education Ltd  a) Fatty acids vary in length (number of carbons) and in the number and locations of double bonds b) Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds c) Unsaturated fatty acids have one or more double bonds © 2015 Pearson Education Ltd Figure 5.10 (a) Saturated fat (b) Unsaturated fat Structural formula of a saturated fat molecule Structural Space-filling formula of an model of unsaturated stearic acid, fat molecule a saturated fatty acid Space-filling model of oleic acid, an unsaturated fatty acid Cis double bond causes bending. © 2015 Pearson Education Ltd  a) Fats made from saturated fatty acids are called saturated fats and are solid at room temperature b) Most animal fats are saturated c) Fats made from unsaturated fatty acids are called unsaturated fats or oils and are liquid at room temperature d) Plant fats and fish fats are usually unsaturated © 2015 Pearson Education Ltd  a) A diet rich in saturated fats may contribute to cardiovascular disease through plaque deposits b) Hydrogenation is the process of converting unsaturated fats to saturated fats by adding hydrogen c) Hydrogenating vegetable oils also creates unsaturated fats with trans double bonds d) These trans fats may contribute more than saturated fats to cardiovascular disease © 2015 Pearson Education Ltd  a) Certain unsaturated fatty acids are not synthesized in the human body b) These must be supplied in the diet c) These essential fatty acids include the omega-3 fatty acids, which are required for normal growth and are thought to provide protection against cardiovascular disease © 2015 Pearson Education Ltd  a) The major function of fats is energy storage b) Humans and other mammals store their long-term food reserves in adipose cells c) Adipose tissue also cushions vital organs and insulates the body © 2015 Pearson Education Ltd Phospholipids a) In a phospholipid, two fatty acids and a phosphate group are attached to glycerol b) The two fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head © 2015 Pearson Education Ltd Figure 5.11 Choline Hydrophilic Hydrophilic head head Phosphate Hydrophobic tails Glycerol (c) Phospholipid symbol Hydrophobic tails Fatty acids Kink due to cis double bond (a) Structural formula (b) Space-filling model (d) Phospholipid bilayer © 2015 Pearson Education Ltd  a) When phospholipids are added to water, they self-assemble into double-layered structures called bilayers b) At the surface of a cell, phospholipids are also arranged in a bilayer, with the hydrophobic tails pointing toward the interior c) The structure of phospholipids results in a bilayer arrangement found in cell membranes d) The existence of cells depends on phospholipids © 2015 Pearson Education Ltd Steroids a) Steroids are lipids characterized by a carbon skeleton consisting of four fused rings b) Cholesterol, a type of steroid, is a component in animal cell membranes and a precursor from which other steroids are synthesized c) A high level of cholesterol in the blood may contribute to cardiovascular disease © 2015 Pearson Education Ltd Figure 5.12 © 2015 Pearson Education Ltd Concept 5.4: Proteins include a diversity of structures, resulting in a wide range of functions a) Proteins account for more than 50% of the dry mass of most cells b) Some proteins speed up chemical reactions c) Other protein functions include defense, storage, transport, cellular communication, movement, or structural support © 2015 Pearson Education Ltd Figure 5.13a Enzymatic proteins Defensive proteins Function: Selective acceleration of Function: Protection against disease chemical reactions Example: Antibodies inactivate and help Example: Digestive enzymes catalyze the destroy viruses and bacteria. hydrolysis of bonds in food molecules. Antibodies Enzyme Bacterium Virus Storage proteins Transport proteins Function: Storage of amino acids Function: Transport of substances Examples: Casein, the protein of milk, is the Examples: Hemoglobin, the iron-containing major source of amino acids for baby protein of vertebrate blood, transports mammals. Plants have storage proteins in oxygen from the lungs to other parts of the their seeds. Ovalbumin is the protein of egg body. Other proteins transport molecules white, used as an amino acid source for the across membranes, as shown here. developing embryo. Transport protein Ovalbumin Amino acids for embryo Cell membrane © 2015 Pearson Education Ltd Figure 5.13b Hormonal proteins Receptor proteins Function: Coordination of an organism’s Function: Response of cell to chemical activities stimuli Example: Insulin, a hormone secreted by the Example: Receptors built into the pancreas, causes other tissues to take up membrane of a nerve cell detect glucose, thus regulating blood sugar, signaling molecules released by other concentration. nerve cells. Receptor Insulin Signaling protein High secreted Normal blood sugar blood sugar molecules Contractile and motor proteins Structural proteins Function: Movement Function: Support Examples: Motor proteins are responsible Examples: Keratin is the protein of hair, for the undulations of cilia and flagella. horns, feathers, and other skin Actin and myosin proteins are responsible appendages. Insects and spiders use silk for the contraction of muscles. fibers to make their cocoons and webs, respectively. Collagen and elastin proteins provide a fibrous framework in animal Actin Myosin connective tissues. Collagen Muscle 30 µm tissue Connective 60 µm tissue © 2015 Pearson Education Ltd  a) Enzymes are proteins that act as catalysts to speed up chemical reactions b) Enzymes can perform their functions repeatedly, functioning as workhorses that carry out the processes of life © 2015 Pearson Education Ltd  a) Proteins are all constructed from the same set of 20 amino acids b) Polypeptides are unbranched polymers built from these amino acids c) A protein is a biologically functional molecule that consists of one or more polypeptides © 2015 Pearson Education Ltd Amino Acid Monomers a) Amino acids are organic molecules with amino and carboxyl groups b) Amino acids differ in their properties due to differing side chains, called R groups © 2015 Pearson Education Ltd Figure 5.UN01 Side chain (R group) 𝛂 carbon Amino Carboxyl group group © 2015 Pearson Education Ltd Figure 5.14 Nonpolar side chains; hydrophobic Side chain (R group) Glycine Alanine Valine Leucine Isoleucine (Gly or G) (Ala or A) (Val or V) (Leu or L) (Ile or I) Methionine Phenylalanine Tryptophan Proline (Met or M) (Phe or F) (Trp or W) (Pro or P) Polar side chains; hydrophilic Serine Threonine Cysteine Tyrosine Asparagine Glutamine (Ser or S) (Thr or T) (Cys or C) (Tyr or Y) (Asn or N) (Gln or Q) Electrically charged side chains; hydrophilic Basic (positively charged) Acidic (negatively charged) Aspartic acid Glutamic acid Lysine Arginine Histidine (Asp or D) (Glu or E) (Lys or K) (Arg or R) (His or H) © 2015 Pearson Education Ltd Polypeptides (Amino Acid Polymers) a) Amino acids are linked by covalent bonds called peptide bonds b) A polypeptide is a polymer of amino acids c) Polypeptides range in length from a few to more than a thousand monomers d) Each polypeptide has a unique linear sequence of amino acids, with a carboxyl end (C-terminus) and an amino end (N-terminus) © 2015 Pearson Education Ltd Figure 5.15 Peptide bond H2O New peptide bond forming Side chains Back- bone Amino end Peptide Carboxyl end (N-terminus) bond (C-terminus) © 2015 Pearson Education Ltd Protein Structure and Function a) The specific activities of proteins result from their intricate three-dimensional architecture b) A functional protein consists of one or more polypeptides precisely twisted, folded, and coiled into a unique shape © 2015 Pearson Education Ltd Figure 5.16 Target molecule Groove Groove (a) A ribbon model (b) A space-filling model (c) A wireframe model © 2015 Pearson Education Ltd  a) The sequence of amino acids determines a protein’s three-dimensional structure b) A protein’s structure determines how it works c) The function of a protein usually depends on its ability to recognize and bind to some other molecule © 2015 Pearson Education Ltd Figure 5.17 Antibody protein Protein from flu virus © 2015 Pearson Education Ltd Four Levels of Protein Structure a) The primary structure of a protein is its unique sequence of amino acids b) Secondary structure, found in most proteins, consists of coils and folds in the polypeptide chain c) Tertiary structure is determined by interactions among various side chains (R groups) d) Quaternary structure results when a protein consists of multiple polypeptide chains © 2015 Pearson Education Ltd Figure 5.18a Primary Structure Amino acids 1 5 10 Amino end 30 25 20 15 35 40 45 50 Primary structure of transthyretin 55 70 65 60 75 80 85 90 95 115 110 105 100 120 125 Carboxyl end © 2015 Pearson Education Ltd Figure 5.18b Secondary Tertiary Quaternary Structure Structure Structure 𝛂 helix Hydrogen bond 𝛃 strand Hydrogen bond Transthyretin Transthyretin polypeptide protein 𝛃 pleated sheet © 2015 Pearson Education Ltd  a) The primary structure of a protein is its sequence of amino acids b) Primary structure is like the order of letters in a long word c) Primary structure is determined by inherited genetic information © 2015 Pearson Education Ltd  a) Typical secondary structures are a coil called an  helix and a folded structure called a  pleated sheet © 2015 Pearson Education Ltd  a) Tertiary structure, the overall shape of a polypeptide, results from interactions between R groups, rather than interactions between backbone constituents b) These interactions include hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals interactions c) Strong covalent bonds called disulfide bridges may reinforce the protein’s structure © 2015 Pearson Education Ltd Figure 5.18d Hydrogen bond Hydrophobic interactions and Van der Waals interactions Disulfide bridge Ionic bond Polypeptide backbone © 2015 Pearson Education Ltd  a) Quaternary structure results when two or more polypeptide chains form one macromolecule b) Collagen is a fibrous protein consisting of three polypeptides coiled like a rope c) Hemoglobin is a globular protein consisting of four polypeptides: two alpha and two beta chains © 2015 Pearson Education Ltd Figure 5.18f Heme Iron 𝛃 subunit 𝛂 subunit 𝛂 subunit 𝛃 subunit Hemoglobin © 2015 Pearson Education Ltd Sickle-Cell Disease: A Change in Primary Structure a) A slight change in primary structure can affect a protein’s structure and ability to function b) Sickle-cell disease, an inherited blood disorder, results from a single amino acid substitution in the protein hemoglobin © 2015 Pearson Education Ltd Figure 5.19 Secondary Primary Quaternary Function Red Blood Cell and Tertiary Structure Structure Shape Structures 1 Normal 𝛃 Normal Proteins do not associate subunit hemoglobin with one another; each 2 carries oxygen. 3 𝛃 Normal 4 5 𝛂 6 7 5 µm 𝛃 𝛂 1 Sickle-cell 𝛃 Sickle-cell Proteins aggregate into a subunit hemoglobin fiber; capacity to 2 carry oxygen 3 𝛃 Sickle-cell is reduced. 4 5 𝛂 6 7 5 µm 𝛃 𝛂 © 2015 Pearson Education Ltd What Determines Protein Structure? a) In addition to primary structure, physical and chemical conditions can affect structure b) Alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein to unravel c) This loss of a protein’s native structure is called denaturation d) A denatured protein is biologically inactive © 2015 Pearson Education Ltd Figure 5.20-1 Normal protein © 2015 Pearson Education Ltd Figure 5.20-2 Normal protein Denatured protein © 2015 Pearson Education Ltd Figure 5.20-3 Normal protein Denatured protein © 2015 Pearson Education Ltd Protein Folding in the Cell a) Chaperonins are protein molecules that assist the proper folding of other proteins b) Diseases such as Alzheimer’s, Parkinson’s, and mad cow disease are associated with misfolded proteins © 2015 Pearson Education Ltd Figure 5.21 Polypeptide Correctly folded Cap protein Hollow cylinder Chaperonin 1 An unfolded 2 Cap attachment 3 The cap (fully polypeptide causes the comes off, assembled) enters the cylinder to and the cylinder change shape, properly from creating a folded one end. hydrophilic protein is environment released. for polypeptide folding. © 2015 Pearson Education Ltd Concept 5.5: Nucleic acids store, transmit, and help express hereditary information a) The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a gene b) Genes consist of DNA, a nucleic acid made of monomers called nucleotides © 2015 Pearson Education Ltd The Roles of Nucleic Acids a) There are two types of nucleic acids a)Deoxyribonucleic acid (DNA) b)Ribonucleic acid (RNA) b) DNA provides directions for its own replication c) DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis d) This process is called gene expression © 2015 Pearson Education Ltd Figure 5.23-1 DNA 1 Synthesis of mRNA mRNA NUCLEUS CYTOPLASM © 2015 Pearson Education Ltd Figure 5.23-2 DNA 1 Synthesis of mRNA mRNA NUCLEUS CYTOPLASM mRNA 2 Movement of mRNA into cytoplasm © 2015 Pearson Education Ltd Figure 5.23-3 DNA 1 Synthesis of mRNA mRNA NUCLEUS CYTOPLASM mRNA 2 Movement of mRNA into Ribosome cytoplasm 3 Synthesis of protein Amino Polypeptide acids © 2015 Pearson Education Ltd  a) Each gene along a DNA molecule directs synthesis of a messenger RNA (mRNA) b) The mRNA molecule interacts with the cell’s protein- synthesizing machinery to direct production of a polypeptide c) The flow of genetic information can be summarized as DNA → RNA → protein © 2015 Pearson Education Ltd The Components of Nucleic Acids a) Nucleic acids are polymers called polynucleotides b) Each polynucleotide is made of monomers called nucleotides c) Each nucleotide consists of a nitrogenous base, a pentose sugar, and one or more phosphate groups d) The portion of a nucleotide without the phosphate group is called a nucleoside © 2015 Pearson Education Ltd  a) Nucleoside = nitrogenous base + sugar b) There are two families of nitrogenous bases a)Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring b)Purines (adenine and guanine) have a six-membered ring fused to a five-membered ring c) In DNA, the sugar is deoxyribose; in RNA, the sugar is ribose d) Nucleotide = nucleoside + phosphate group © 2015 Pearson Education Ltd Figure 5.24 NITROGENOUS BASES Pyrimidines Sugar-phosphate backbone 5′ end (on blue background) Cytosine Thymine Uracil 5′C (C) (T, in DNA) (U, in RNA) 3′C Purines Nucleoside Nitrogenous base Adenine (A) Guanine (G) 5′C SUGARS 1′C Phosphate 3′C 5′C group Sugar (pentose) 3′C (b) Nucleotide Deoxyribose Ribose (in DNA) 3′ end (in DNA) (a) Polynucleotide, or nucleic acid (c) Nucleoside components © 2015 Pearson Education Ltd Animation: DNA and RNA Structure © 2015 Pearson Education Ltd Nucleotide Polymers a) Nucleotides are linked together to build a polynucleotide b) Adjacent nucleotides are joined by a phosphodiester linkage, which consists of a phosphate group that links the sugars of two nucleotides c) These links create a backbone of sugar-phosphate units with nitrogenous bases as appendages d) The sequence of bases along a DNA or mRNA polymer is unique for each gene © 2015 Pearson Education Ltd The Structures of DNA and RNA Molecules a) DNA molecules have two polynucleotides spiraling around an imaginary axis, forming a double helix b) The backbones run in opposite 5 → 3 directions from each other, an arrangement referred to as antiparallel © 2015 Pearson Education Ltd  a) Only certain bases in DNA pair up and form hydrogen bonds: adenine (A) always with thymine (T), and guanine (G) always with cytosine (C) b) This is called complementary base pairing © 2015 Pearson Education Ltd  a) RNA, in contrast to DNA, is single stranded b) In RNA, thymine is replaced by uracil (U) so A and U pair c) While DNA always exists as a double helix, RNA molecules are more variable in form © 2015 Pearson Education Ltd Figure 5.25 5′ 3′ Sugar-phosphate backbones Hydrogen bonds Base pair joined by hydrogen bonding 3′ 5′ Base pair joined by hydrogen bonding (a) DNA (b) Transfer RNA © 2015 Pearson Education Ltd