Macromolecules PDF

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...

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  HOW ARE POLYMERS MADE? Dehydration Synthesis: Create polymers from monomers. Two monomers are joined by removing one molecule of water.  HOW POLYMERS ARE BROKEN: ▪Hydrolysis: Occurs when water is added to spit large molecules. This occurs in the reverse of the above reaction. CARBOHYDRATE: SUGARS ▪ Monosaccharides have molecular formulas that are usually multiples of CH2O ▪ Ratio 1:2:1 in CHO ▪ Glucose (C6H12O6) is the most common monosaccharide ▪ Others: Fructose and Galactose ▪ 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) Aldoses Glyceraldehyde Ribose Glucose Galactose Ketoses Dihydroxyacetone Ribulose Fructose Fig. 5-3a Trioses (C3H6O3) Pentoses (C5H10O5) Hexoses (C6H12O6) Aldoses Glyceraldehyde Ribose Glucose Galactose Fig. 5-3b Trioses (C3H6O3) Pentoses (C5H10O5) Hexoses (C6H12O6) Ketoses Dihydroxyacetone Ribulose Fructose Fig. 5-4a (a) Linear and ring forms ▪ A disaccharide is formed when a dehydration reaction joins two monosaccharides ex: sucrose, lactose, maltose ▪ This covalent bond is called a glycosidic linkage Animation: Disaccharides Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings POLYSACCHARIDES: COMPLEX SUGARS ▪ 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 Starch, a storage polysaccharide of plants, consists entirely of glucose monomers. Plants store surplus starch as granules within chloroplasts and other plastids Glycogen is a storage polysaccharide in animals. Humans and other vertebrates store glycogen mainly in liver and muscle cells cellulose is a major component of the tough wall of plant cells 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. 5-7bc Cellulose: 1–4 linkage 3000+ glucose  Amylose vs. Amylopectin Amylose: long, straight starch molecule that does not gelatinize during cooking. Fully separates 200-20,000 glucose Ex: Jasmine and Basmati Amylopectin: highly branched starch molecule that is responsible for making rice gelatinous and sticky 2000- 2 million glucose 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; consist mostly of hydrocarbons, ▪ Structure: mostly C,H (with carboxyl ) ▪ Vital Functions: ▪ Long term energy storage ▪ cushions vital organs and insulates the body ▪ Membrane makeup ▪ Steroids/Hormones ▪ Cholesterol Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 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 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  Types of Fatty Acids: ▪ Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds ▪ Fats made from saturated fatty acids are called saturated fats, and are solid at room temperature ▪ Most animal fats are saturated ▪ Unsaturated fatty acids have one or more double bonds ▪ Fats made from unsaturated fatty acids are called unsaturated fats or oils, and MOST (excludes Trans-fats) are liquid at room temperature ▪ Plant fats and fish fats are usually unsaturated Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings UNSATURATED ISOMERS: Almost all living organisms synthesize and incorporate cis-fatty acids into their lipids.. A cis-isomer is bent or “kinked,” preventing cis-fatty acids from packing closely together. Trans-fatty acids are isomers often created during commercial food production. Trans-isomers are structurally similar to saturated fatty acids because the hydrocarbon chain does not contain a “kink.”. --created by exposure to extreme heat, such as when oils are superheated during deep-frying. Trans-fats are solid at room temp despite the double bond. POLYMER: 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 Amphipathic Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-14 Hydrophilic WATER head Hydrophobic WATER tail Fig. 5-11b Polymer: Triglyceride Major stored form of fat. lipogenesis: creates lipids (fat) from the acetyl CoA (in cytoplasm of adipocytes (fat cells) and hepatocytes (liver cells). When you eat more glucose or carbohydrates than your body needs, your system uses acetyl CoA to turn the excess into fat. =long term energy store To obtain energy from fat -Triglycerides must first be broken down by hydrolysis into their two principal components, fatty acids and glycerol. (Lipolysis in cytoplasm.) The resulting fatty acids are oxidized into acetyl CoA, which is used by the Krebs cycle.  LIPID EXAMPLES: STEROIDS AND CHOLESTEROL: -made in smooth ER Cholesterol: -membrane fluidity -consumed or produced -carried around by lipoproteins (VLDL, LDL, HDL) Steroids: -sex hormones -estrogen, progesterone, testosterone,etc.  PROTEINS: Monomer: Amino acids are organic molecules with carboxyl and amino groups Amino acids differ in their properties due to differing side chains, called R Glycine Valine groups Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-17 Nonpolar Glycine Alanine Valine Leucine Isoleucine (Gly or G) (Ala or A) (Val or V) (Leu or L) (Ile or I) Methionine Phenylalanine Trypotphan Proline (Met or M) (Phe or F) (Trp or W) (Pro or P) Polar 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 Acidic Basic Aspartic acid Glutamic acid Lysine Arginine Histidine (Asp or D) (Glu or E) (Lys or K) (Arg or R) (His or H)  PROTEIN POLYMERS ▪ Polymer: Polypeptides are polymers built from the same set of 20 amino acids ▪ A protein consists of one or more polypeptides ▪ Amino acids are linked by peptide bonds ▪ 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 FOUR LEVELS OF PROTEIN STRUCTURE Primary ▪ The primary structure of a protein is its unique sequence of amino acids Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings FOUR LEVELS OF PROTEIN STRUCTURE Secondary ▪Typical secondary structures are a coil called an α helix and a folded structure called a β pleated sheet resulting from hydrogen bonds between the backbone components: hydrogen (in amino group) and oxygen (in carbonyl portion of carboxyl) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  FOUR LEVELS OF PROTEIN STRUCTURE Tertiary ▪determined by interactions among various side chains (R groups) ▪ A. Hydrophobic Interactions: (non-polar) side chains usually end up in the core of a protein out of contact with water. (usually hydrocarbons) ▪ B. Ionic bonds between charged side chains (charges shown C. Hydrogen bonds between polar side chains (usually O and H) D. Disulfide Bridges: covalent bonds between cysteine monomers that have sulfhydryl groups on their side chains. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings FOUR LEVELS OF PROTEIN STRUCTURE Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings FOUR LEVELS OF PROTEIN STRUCTURE Quaternary: ▪ Quaternary structure results when a protein consists of multiple polypeptide chains ▪ 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 PROTEINS ▪ Proteins account for more than 50% of the dry mass of most cells ▪ Protein functions include ▪ structural support ▪ Regulation ▪ transport ▪ cellular communication ▪ enzymes ▪ Movement ▪ immunity Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings ▪ 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 Animation: Enzymes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PROTEIN STRUCTURE AND FUNCTION ▪ A functional protein consists of one or more polypeptides twisted, folded, and coiled into a unique shape ▪ Example 1: Globular proteins – Amylase (enzyme in starch digestion) ▪ Example 2: Fibrous proteins –Collagen Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings ANTIBODY VS. INFLUENZA MORPHINE V. ENDORPHIN Fig. 5-22 Normal hemoglobin Sickle-cell hemoglobin Val His Leu Thr Pro Glu Glu Primary Primary Val His Leu Thr Pro Val Glu structure structure 1 2 3 4 5 6 7 1 2 3 4 5 6 7 Exposed Secondary Secondary hydrophobic and tertiary  subunit and tertiary region  subunit structures structures     Quaternary Normal Quaternary Sickle-cell structure hemoglobin structure hemoglobin (top view)     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 blood Red blood Fibers of abnormal cell shape cells are full of cell shape hemoglobin deform individual red blood cell into hemoglobin sickle shape. moledules, each carrying oxygen. Fig. 5-21 Primary Secondary Tertiary Quaternary Structure Structure Structure Structure  pleated sheet + H3N Amino end Examples of amino acid subunits  helix Fig. 5-21a Primary Structure 1 + 5 H3N Amino end 10 15 Amino acid subunits 20 25 Fig. 5-21b 1 + 5 H3N Amino end 10 15 Amino acid subunits 20 25 75 80 85 90 95 105 100 110 115 120 125 Carboxyl end Fig. 5-21c Secondary Structure  pleated sheet Examples of amino acid subunits  helix 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 Fig. 5-21g Polypeptide  Chains chain Iron Heme  Chains Hemoglobin Collagen THE STRUCTURE OF NUCLEIC ACIDS ▪ made of monomers called nucleotides ▪ Each nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphate group **Numbering of sugar Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings NUCLEOTIDE MONOMERS ▪ There are two families of nitrogenous bases: ▪ Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring Cytosine Thymine Uracil ▪ Purines (adenine and guanine) have a six-membered ring fused to a five-membered ring Adenine Guanine Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings FORMING A POLYMER: ▪ Phosphodiester bonds form between nucleotides. ▪ 5’ phosphate end of one nucleotide to 3’ -OH of another nucleotide THE POLYMERS OF NUCLEIC ACIDS ▪ There are two types of polymers: Deoxyribose Ribose ▪ Deoxyribonucleic acid (DNA): ▪ Sugar: deoxyribose ▪ Bases: Adenine, Thymine Cytosine, Guanine ▪ Double Stranded ▪ Anti-parallel ▪ Ribonucleic acid (RNA): ▪ Sugar: ribose ▪ Bases: Adenine, Uracil, Cytosine, Guanine ▪ Single Stranded Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  DNA Hydrogen bonds connect the to DNA strands. Adenine and Thymine: 2 hydrogen bonds Cytosine and Guanine: 3 hydrogen bonds NUCLEIC ACID FUNCTIONS ▪ 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 Fig. 5-26-1 DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM Fig. 5-26-2 DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM mRNA 2 Movement of mRNA into cytoplasm via nuclear pore Fig. 5-26-3 DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM mRNA 2 Movement of mRNA into cytoplasm Ribosome via nuclear pore 3 Synthesis of protein Amino Polypeptide acids