Agenda Chapter 3 The molecules of life Macromolecules --Detour into Healthy Pig Land 4. Nucelic acids Chapter 3: Macromolecules Macromolecules is just a fancy word for: Giant Molecules Made From Smaller Building Blocks Carbohydrates Lipids Proteins Nucleic acids Can you think of any examples of these types of macromolecules in your body? What are organic compounds? In chemistry, organic compounds contain carbon and hydrogen Most biologically relevant organic compounds are soluble in water This is because most of these organic compounds contain a polar bond somewhere in the molecule Macromolecules (in general) Most macromolecules are polymers Polymers are made by stringing together many building blocks smaller molecules, building blocks called monomers Short polymer Longer polymer (a) Dehydration synthesis of a polymer Monomer Figure 3.7A POLYMER MONOMER Most of the carbs we will talk about in this class are carbon based, ring structures Used as energy source Used for structural components of cells 1
Monosaccharides Disaccharides Polysaccharides Glucose is a monosaccharide Glucose is a single sugar. Note that it is a ring structure with 6 carbon atoms. Other monosaccharides: fructose, galactose Maltose is a disaccharide Linking two glucose monomers together yields maltose monomer monomer Sucrose and Lactose are other disaccharides! Polysaccharides Long chains of linked glucose monomers 1. Starch 2. Glycogen 3. Cellulose Linear chain Maltose Polysaccharides Glucose monomer Why is cellulose a good structural component? (a) Starch Starch granules in potato tuber cells Glycogen Granules In muscle tissue (b) Glycogen Cellulose fibril in a plant cell wall Cellulose molecules (c) Cellulose Monomer + Monomer + Monomer = Polymer This electron micrograph shows the cellulose fibrils in the cell wall of a green alga. These long, rigid fibrils are a clear reflection of the nature of the cellulose molecules of which they are composed. 2
Lipids form essential structures in cells Lipids are important energy stores Lipids, as a class, are a very diverse group of molecules What do you think is the unifying characteristic of lipids? Do water and oil mix? LIPIDS ARE HYDROPHOBIC Non-polar lipid molecules are excluded by water. Fats or Fatty Acids Triglycerides One of these long, hydrocarbon (H and C) chains is a Fatty Acid Glycerol Fatty acid Glycerol Fatty Acids normally don t exist as free molecules. Fatty acids are linked to a molecule of glycerol for storage! Triglycerides are three fatty acids linked to one glycerol molecule Saturated and Unsaturated Fats Saturated Saturated and Unsaturated Fats Saturated Unsaturated Unsaturated 3
Diversity of structure in fatty acids as a result of chemical bonds Why are some fatty acids bent and some straight? What is meant by saturated fat? What is saturated? What effect does saturation have on the shape of the chain? Saturated Unsaturated Unsaturated fats contain one or more C-C double bonds along their hydrocarbon chain. Cis- is a chemical term that refers the orientation of the hydrogens around that double bond How does molecular structure affect the physical state of matter? Omega-3 Fatty Acids -Omega-3 oils, which are healthy unsaturated oils, are oils that contain fatty acids with a double bond after the 3rd carbon atom. -Omega-6 oils contain a double bond after the 6th carbon atom. -A healthy diet should contain a balance of both omega-3 and omega-6 oils. -Diets rich in omega-3 fats are correlated with better cardiovascular health. Dietary Sources Salmon, trout, tuna Canola oil Flax-seed oil Transgenic pigs???? The primary benefit of Omega-3 oil is thought to be the reduction of platelet activity (blood clotting) and plaque formation which in turn can prevent heart attacks. Trans-Fats: The real bad guy Hydrogenation: a process that artificially converts polyunsaturated fats, like vegetable oil, into more saturated fats (fewer double bonds). Trans-fats are a byproduct of this process Why do you think food companies want to use hydrogenated fats in their products? 4
Steroids cholesterol Trans-Fats All consist of a complex ring structure Cholesterol is the precursor for Testosterone and Estrogen and other steroid hormones Component of animal cell membranes Signaling molecules Sexual function Tissue metabolism Testosterone Estrogen Phospholipids and Glycolipids Phospholipid Glycerol Chemist s version Biologist s version Phospholipid Glycolipid Chemist s version Phospholipid bilayer Biologist s version H20 Sesame Street version Phospholipid bilayer Forms the boundary between a cell and its environment Hydrophobic core, with hydrophilic ends H20 Two layers of phospholipids, stacked on each other, with the hydrophobic tails of each layer facing one another. 5
Zoom in on a phospholipid http://images.google.com/imgres?imgurl=http://telstar.ote.cmu.edu/hughes/tutorial/cellmembranes/img/cholesterol.gif&i mgrefurl=http://telstar.ote.cmu.edu/hughes/tutorial/cellmembranes/&h=136&w=243&sz=15&tbnid=clpxow0yfd_u1m:& tbnh=58&tbnw=105&hl=en&start=42&prev=/images%3fq%3dcell%2bphospholipid%2bbilayer%26start%3d40%26svn um%3d10%26hl%3den%26lr%3d%26sa%3dn Proteins A protein is a polymer of amino acid monomers Proteins perform most of the tasks the body needs to function They are the most elaborate of life s molecules Proteins are polymers (chains) of amino acids A single, generalized amino acid Proteins are polymers (chains) of amino acids Amino Acid 1 Amino Acid 2 Amino Acid 3 + + = Monomer + Monomer + Monomer = Polymer Amino Acid 1 Amino Acid 2 Amino Acid 3 PEPTIDE BOND 20 Amino Acids You do not need to memorize these. Just notice the white boxes, they are the R groups. Notice that each amino acid has a different R group, with a different structure. 6
The four types of proteins: Your book is lying to you, there are way too many proteins to fit into only four categories!! Your body has tens of thousands of different kinds of proteins The arrangement (sequence) of amino acids makes each protein have a different shape and function! (b) Storage proteins (d) Transport proteins (a) Structural proteins Hey, you forgot ENZYMES! (c) Contractile proteins Protein Shape Proteins have four levels of structure Hydrogen bond A slight change in the primary structure of a protein affects its ability to function One amino acid change in hemoglobin causes sickle cell anemia Amino acid Pleated sheet Polypeptide (single subunit) (a) Primary structure Hydrogen bond Alpha helix (b) Secondary structure (c) Tertiary structure Complete protein, with four polypeptide subunits (d) Quaternary structure 1 (a) Normal red blood cell 1 (b) Sickled red blood cell 2 7... 146 3 6 4 5 Normal hemoglobin 2 7... 146 3 6 4 5 Sickle-cell hemoglobin Protein Structure Secondary Structure δ - δ + δ + δ - Tertiary Structure δ - δ + Quaternary Structure Enzymes are Proteins Enzymes catalyze (speed up) biological reactions Lactose lactase δ - δ+ δ - δ + δ - δ + Peptide bond Primary Structure Lactose is cleaved by the enzyme lactase into a glucose and a galactose monomer 7
4. Nucleic acids There are two types of nucleic acids 1. DNA 2. RNA -store information -provide the directions for building proteins 4. Nucleic Acids Nucleic Acids are Polymers, too! The monomers of nucleic acids are nucleotides Nucleotide consists of Sugar Phosphate group Nitrogenous base Sugar Phosphate Base Nucleotide monomer 4. Nucleic Acids Nucleotide monomers are linked into long chains These chains are called polynucleotides, or DNA strands A sugar-phosphate backbone joins them together Backbone Nucleotide Bases (a) DNA strand 4. Nucleic Acids DNA and RNA DNA is a double stranded molecule. DNA is two long strands of nucleotides, held together by hydrogen bonds between the nucleotide bases. RNA is a single stranded nucleic acid 4. Nucleic Acids Each DNA nucleotide has one of the following bases Adenine (A) Guanine (G) Thymine (T) Cytosine (C) -RNA uses Uracil (U) in place of Thymine (T) Thymine (T) Adenine (A) Cytosine (C) Guanine (G) Figure 3.25 Why are DNA and RNA so important? DNA is merely a long string of nucleotides, and nucleotide bases These bases are like letters in an alphabet The sentences they form, are genes Genes code for proteins! 8
DNA RNA protein DNA is copied into RNA RNA is then read and turned into protein Helpful chart at end of Chapter 3 9