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The Chemistry of Organic Molecules Chapter 3 Organic Molecules 3.1 Organic Molecules Organic Chemistry- the chemistry of living organisms. Inorganic Chemistry- chemistry of nonliving matter. Organic- molecules and compounds that contain both carbon and hydrogen atoms. Four classes of organic molecules in living things: 1. Lipids 2. Carbohydrates 3. Proteins 4. Nucleic Acids The Carbon Atom Six electrons Always form covalent bonds (almost always) C-C bond is so stable it allows the formation of long chains The Carbon Atom Carbons can also form a ring structure when placed in water environments. Double bonds between carbons aren’t as flexible, restrict movement Can also form triple bonds with itself. Carbon Skeleton and Functional Groups Carbon chains are called the skeleton or backbone. Functional group- specific combination of atoms that always have same chemical properties regardless of carbon skeleton attached to it. Isomers Identical molecular formulas but different arrangements of atoms. Biomolecules of Cells Polymers- large number of the same subunit linked together (carbs, proteins, and nucleic acids) Lipids are made of different subunits linked together so they are NOT polymers Synthesis and Degradation Build- dehydration reactions –OH AND –H groups are removed making water. Break down- hydrolysis reactions –OH and –H are added Enzymes that act as catalysts are usually needed for these to occur. Carbohydrates 3.2 Carbohydrates Immediate energy source in living organisms. 1:2:1 Chain length varies. Monosaccharides-monomer subunits Polysaccharides- long chains or monosaccharides. Monosaccharides Simple sugars Carbon backbone of 3 to 7 carbons Pentose Hexose Glucose is a hexose monosaccharide Ribose and deoxyribose are pentose ones Disaccharides Two monosaccharides that have joined together. We use sucrose to sweeten our food. Lactose Polysaccharides: Energy Storing Molecules Monosaccharides linked together. “Complex carbs” Short-term energy storage because not as soluble in water and larger than simple sugars. Can’t easily get through the plasma membrane Plants- starch Animals- glycogen Polysaccharides: Structural Molecules Plants- cellulose Most abundant organic molecule on earth Wood, cotton animals/fungi- peptidoglycan Chitin- found in exoskeleton of insects, lobsters, and crabs. Lipids Fats or triglycerides Insulation and long-term storage In plants, they are referred to as oils. Triglycerides 1. Fatty acid Each has a long hydrocarbon chain with an EVEN number of carbons and a –COOH Saturated fatty acid- no double bonds Unsaturated fatty acid- double bonds between C-C, melt faster Trans fat is a triglyceride that has one bond in the trans configuration 2. Glycerol 3-C compound with three –OH groups Soluble in water Phospholipids Triglycerides except in place of 3rd fatty acid, there is a polar phosphate group Hydrophilic heads and hydrophobic tails Steroids Lipid structures with skeleton of four fused carbon rings. Cholesterol provides stability to cell membrane and is the precursor to other steroids. Testosterone, estrogen, etc. Proteins 50% of the dry weight of most cells is protein. Play a role in metabolism, support, transport, defense, regulation, and motion. Hundreds of thousands proteins identified so far. Amino Acids: Protein Monomers Proteins are made up of aa. 20 aa total. Amino Acids When two or more amino acids are linked together it is called a peptide. When many are linked together it is called a polypeptide. Peptide Bond Shape of Proteins Four levels of structural organization Primary- linear sequence of aa Secondary- polypeptide folds or curls Tertiary- folding into three dimensional shape Quaternary-more than one polypeptide Nucleic Acids Polymers of nucleotides, store info, conduct chemical reactions. DNA is one type of NA Stores info Specifies order of aa for proteins RNA mRNA is a copy of gene that specifies what aa sequence will be during the process of protein synthesis. tRNA helps translate for protein rRNA works as enzyme to form peptide bonds between aa in the polypeptide Structure of DNA and RNA 1. Sugar DNA-deoxyribose RNA-ribose 2. Phosphate 3. Nitrogen containing base 1. DNA- A, T, G, C 2. RNA- A, U, G, C ATP (Adenosine Triphosphate) Adenine and ribose and three phosphates (3 P) ADP- diphosphate (2 P) Used for energy by the cell.
