Organic Inorganic carbon backbone functional groups

Transcription

1 Biological Molecules hapter 3 arbon in Biological Molecules Organic molecules Derived from living organisms ontain a carbon backbone Inorganic molecules O 2, O, and all molecules without carbon Topoisomerase protein bound to DNA arbon 6 arbon arbon is versatile and can form up to 4 covalent bonds. Because it can make so many different bonds, arbon is present in nearly every structure in a cell. arbon 6 arbon Most organic molecules have a carbon backbone. A chain of carbon atoms bonded together. Branching off of the backbone are a variety of functional groups. Small molecules with a specific function that determine the chemical nature of the larger molecule.

2 6 12 O 6 Organic Molecules often contain Functional Groups Synthesis of Organic Molecules A modular approach: small organic molecules, subunits, are combined to form larger molecules. Monomers, one part, single subunits. Example: sugars Polymers, many parts, long chains of many subunits. Example: starches Dehydration Synthesis To form by removing water. 1. A hydrogen ion ( + ) is removed from one subunit. 2. A hydroxyl group (O - ) is removed from the a second subunit. 3. The two subunits can now covalently bond and the + and O - can form water.

3 ydrolysis To break apart with water Types of Biological Molecules Water is ionized and the + and O - bind to each new subunit. The major way our digestive system breaks down food. arbohydrates Lipids Proteins Nucleic Acids RNA Polymerase protein synthesizing RNA strand from a template DNA helix. Ball and Stick Model hemical Structure arbohydrates Molecules composed of carbon, hydrogen, and oxygen in a ratio of ~1:2:1 --> ( 2 O) n Monosaccharide: composed of one sugar. Glucose, fructose, galactose = 6 12 O 6 = hemical Formula Space-Filling Model glucose

4 Disaccharide: composed of two sugars. Short-term energy storage. reated by dehydration synthesis of two monosaccharides. Examples: sucrose, maltose, lactose Polysaccharide: composed of many sugars. Long-term storage Structural materials Starches, glycogen, cellulose Polysaccharide: composed of many sugars. Long-term storage Structural materials Starches, glycogen, cellulose Lipids omposed almost entirely of carbon and hydrogen. ydrophobic and insoluble in water. 3 classes of lipids: Oils, fats, and waxes Phospholipids Steroids, and other fused-ring compounds

5 Oils, Fats, and Waxes Formed by dehydration of glycerol and fatty acid subunits. Fatty acids are long strands of 2 with a carboxylic acid functional group (-OO) on the end. Oils, Fats, and Waxes Saturated fatty acids: all excess bonds occupied by hydrogen atoms. Usually solid at room temperature. Unsaturated fatty acids: double-bonded carbon atoms, resulting in fewer hydrogen atoms. Liquid at room temperature. Saturated Fat (butter, lard) cis-unsaturated Fat (oils) trans-unsaturated Fat (margarine) Trans Fats hemically modified unsaturated fats by hydrogenation. Example: partiallyhydrogenated soybean oil. Keeps oils solid at room temperature Difficult to metabolize. Phospholipids Makes up the plasma membrane surrounding cells. onsists of Phosphate-nitrogen head (hydrophilic) 2 fatty acid tails (hydrophobic).

6 Phospholipid ell Membrane: a Phospholipid Bilayer ydrophilic ead The hydrophobic interior of the membrane inhibits water movement, preventing leaks. ydrophobic Tail Lipid Bilayer Steroids 4 carbon rings fused together with functional groups. Formed by a similar biochemical pathway as other lipids. All are synthesized from cholesterol. holesterol comes from animal derived foods. Most animals synthesize all they need. holesterol Aids in keeping the membrane fluid and protects neurons in the brain. Non-polar. arried through the bloodstream on lipoproteins. igh-density lipoproteins (DL) = "good" cholesterol. Low-density lipoproteins (LDL) = "bad" cholesterol. LDL is ~100x larger than DL. LDL can be deposited in arteries forming plaques. ATP Synthase Actin ollagen Myosin Antibody Proteins omposed of chains of amino acids. Many different functions: Enzymes guide chemical reactions. Structural proteins: collagen, keratin. Movement: actin and myosin. Defense: antibodies. Protein crystal structures from the RSB Protein Data Bank

7 Amino Acids The Twenty Amino Acids All amino acids share the same general structure: Amino group (N2) arboxylic group (OO) Variable group (R) 20 different amino acids, each with a different R group. Protein Synthesis Proteins are synthesized by a dehydration reaction between two amino acids. Proteins have 4 Levels of Structure 1. Primary structure: sequence of amino acids. 2. Secondary structure: helix or ß-sheet held together by hydrogen bonds. 3. Tertiary structure: complex 3-dimensional shape of the polypeptide. 4. Quaternary structure: individual polypeptides subunits can link to form a larger protein. Short amino acid chains are called peptides. Longer amino acid chains (>50 aa) are called polypeptides.

8 Keratin and air Texture Disulfide bonds between amino acids (cysteine) in keratin result in curly, wavy, or straight hair. Nucleic Acids Long chains of nucleotide subunits. Nucleotides consist of a 5-carbon sugar, a phosphate group, and a nitrogen-containing base (the variable group). Nucleotides are covalently linked via their phosphate groups to form nucleic acids. urly air Two Main Types of Nucleotides Ribose nucleotides (subunit of RNA) Ribonucleic acid (RNA) is copied from DNA and is involved in protein synthesis. Deoxyribose nucleotides (subunit of DNA) Deoxyribonucleic acid (DNA) contains the genetic material of all living organisms. DNA Linked deoxyribose nucleotides form a single-stranded DNA (ssdna) molecule. Two ssdna chains bind with hydrogen bonds between the nitrogen-containing bases to form a helical structure.

9 Other nucleotides: yclic AMP (adenosine monophosphate) Intracellular messenger. Adenosine triphosphate, ATP Energy currency of all cells. NAD + and FAD Electron carriers. omework hapter 3 Thinking Through the oncepts, Review Question #5 Applying the oncepts #1