Biology The Molecules of Cells
Carbon and Functional Groups • Why is Carbon Important? A. What is Organic Chemistry? • The study of carbon compounds is know as Organic Chemistry • Organic molecules are molecules that contain carbon
A Look at History • Vitalism (Early 19th Century) Belief in a life force outside the jurisdiction of chemical/physical laws. • It was believed that only living organisms could produce organic compounds. • Mechanism – Belief that all natural phenomena are governed by physical and chemical laws. • Began to synthesize organic compounds from inorganic molecules.
B. Carbon – A Close Look • Has an atomic number of 6, leaving 4 valence electrons. • Forms four covalent bonds. C. Carbon Variations • Length (Ethylene to Fatty Acids) • Shape (Straight Chain, branched, rings)
D. Hydrocarbons • Molecules containing only Carbon and Hydrogen • Major components of fossil fuels. E. Isomers • Compounds with the same molecular formula but with different structures and hence different properties.
II. Functional Groups • Contribute to the molecular diversity of life. • Frequently bonded to the carbon skeleton of organic molecules. • Often determine the unique chemical properties of organic molecules. • Are the regions of organic molecules which are commonly chemically reactive.
III. Macromolecules • A. Polymer Principal • Most Macromolecules are polymers. • Polymer – large molecule consisting of many identical or similar subunits connected together. • Monomer – Subunit or building block molecule of a polymer. • Macromolecule – large organic polymer
B. Four classes of macromolecules 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic Acids
IV. Carbohydrates • Fuel and building material. • Organic molecules made of sugars and their polymers. • Monomers are called monosaccharides. • Classified by the number of simple sugars.
Monosaccharides • Simple sugar in which C, H, & O occur in a ratio of (CH2O) • Major nutrients for cells (glucose) • Store energy in their chemical bonds.
B. Disaccharides • A double sugar consisting of two monosaccharides joined by glycosidic linkage
C. Polysaccharides • Macromolecules that are polymers of a few hundred or thousand monosaccharides. • Formed by dehydration synthesis. • Have two functions: energy storage and structural support.
V. Lipids • Insoluble in water • Groups include; fats, phospholipids, and steroids • Fats • Store large amounts of energy (One gram of fat stores twice as much energy as a gram of polysaccharide) • Cushions vital organs in mammals. • Insulates against heat loss.
Two classes of fats; saturated fat and unsaturated fat. • Saturated fat • No double bonds between carbons in fatty acid tail • Most animal fats (Ex: bacon grease, butter) 2. Unsaturated fat • There are double bonds between carbons in fatty acid tail. • Most plant fats (Ex: peanut and olive oil)
B. Phospholipids • Major constituents of cell membranes C. Steroids • Lipids which have four fused carbon rings with various functional groups attached.
VI. Proteins • A macromolecule that consists of one or more polypeptide chains folded and coiled into specific conformations. • Polypeptide chain – polymers of amino acids that are arranged in a specific linear sequence and are linked by peptide bonds. • Are abundant – making up 50% or more of cellular dry weight.
Have many functions • Structural support • Catalysis of biochemical reactions (enzymes) • Transport (hemoglobin) • Signaling (chemical messengers) • Movement (contractile proteins) • Defense against antigens (antibodies)
Amino Acids • Only 20 amino acids make millions of different proteins • Building block molecules of a protein • Consists of;
B. Peptide Bond – a covalent bond formed by a dehydration synthesis reaction.
C. Function is dependent upon structure. • Protein conformation – 3D shape of a protein. • Denaturation – A process that alters a proteins conformation and biological activity. • Transfer to an organic solvent. • Breaking hydrogen bonds, ionic bonds, and disulfide bridges • Excessive heat
1. Four levels of protein structure. a. Primary structure – unique sequence of amino acids in a protein. b. Secondary structure – regular, repeated coiling and folding of a protein’s polypeptide backbone. i. Two types: Alpha helix and Beta pleated sheets c. Tertiary structure – the three-dimensional shape of a protein. d. Quaternary structure – interactions between several polypeptide chains.
VII. Nucleic Acids • Stores and transmits hereditary information. • Two types – DNA & RNA A. DNA (Deoxyribonucleic acid) • Contains coded information that programs all cell activity • Contains directions for its own replication
DNA continued • Is copied and passed from one generation of cells to another. • In eukaryotic cells, found primarily in the nucleus • Makes up your genes B. RNA (Ribonucleic Acid) • Functions in the actual synthesis of proteins coded for by DNA
C. Parts of Nucleic Acid • Nucleic acid – Polymer of nucleotides linked together • Nucleotide – Building block molecule, made up of;
D. Nitrogenous bases • Two families of bases • Pyrimidine – Six membered ring - Includes: Cytosine (C), Thymine (T), & Uracil (U) 2. Purine – Five membered ring fused to a six-membered ring - Includes: Adenine (A) and Guanine (G)
E. Functions of Nucleotides • Monomers for nucleic acids • Transfer chemical energy from one molecule to another (ATP) • Are electron acceptors in enzyme – controlled redox reactions (NAD) • Each gene contains a unique linear sequence of nitrogenous bases; which in turn code for a unique linear sequence of amino acids in a protein.
F. DNA and Proteins • Can be used as a tape measure of evolution. • More closely related species have more similar sequences of DNA and amino acids.