[size=18pt]I. Cells Contain Organic Molecules[size=14pt]A. Most Common Elements[size=14pt]1. Most common elements in living things are carbon, hydrogen, nitrogen, and oxygen.[size=14pt]2. These four elements constitute about 95% of your body weight.[size=14pt]3. Chemistry of carbon allows the formation of an enormous variety of organic molecules. [size=14pt]4. Organic molecules have carbon and hydrogen; determine structure and function of living things.[size=14pt]5. Inorganic molecules do not contain carbon and hydrogen together; inorganic molecules (e.g., NaCl) can play important roles in living things. [size=14pt]B. Small Molecules Have Functional Groups[size=14pt]1. Carbon has four electrons in outer shell; bonds with up to four other atoms (usually H, O, N, or another C). [size=14pt]2. Ability of carbon to bond to itself makes possible carbon chains and rings; these structures serve as the backbones of organic molecules.[size=14pt]3. Functional groups areclusters of atoms with characteristic structure and functions.[size=14pt]a. Polar molecules (with +/- charges) are attracted to water molecules and are hydrophilic. [size=14pt]b. Nonpolar molecules are repelled by water and do not dissolve in water; are hydrophobic.[size=14pt]c. Hydrocarbon is hydrophobic except when it has an attached ionized functional group such as carboxyl (acid) ( COOH); then molecule is hydrophilic. [size=14pt]d. Cells are 70-90% water; degree organic molecules interact with water affects their function. [size=14pt]4. Isomers are molecules with identical molecular formulas but differ in arrangement of their atoms
[size=14pt]C. Large Organic Molecules Have Monomers[size=14pt]1. Each small organic molecule can be a unit of a large organic molecule called a macromolecule.[size=14pt]2. Small organic molecules (e.g., monosaccharides, glycerol and fatty acid, amino acids, and nucleotides) that can serve as monomers, the subunits of polymers.[size=14pt]3. Polymers are the large macromolecules composed of three to millions of monomer subunits.[size=14pt]4. Four classes of macromolecules (polysaccharides or carbohydrates, triglycerides or lipids, polypeptides or proteins, & nucleic acids such as DNA & RNA) provide great diversity.[size=14pt]D. Condensation Is the Reverse of Hydration[size=14pt]1. Macromolecules build by different bonding of different monomers; mechanism of joining and breaking these bonds is condensation and hydrolysis.[size=14pt]2. Cellular enzymes carry out condensation and hydrolysis of polymers.[size=14pt]3. Condensationinvolves a dehydration synthesis because a water is removed (dehydration) and a bond is made (synthesis).[size=14pt]a. When two monomers join, a hydroxyl ( OH) group is removed from one monomer and a hydrogen is removed from the other.[size=14pt]b. This produces the water given off during a condensation reaction. [size=14pt]4. Hydrolysis(hydration)reactions break down polymers in reverse of condensation; a hydroxyl ( OH) group from water attaches to one monomer and hydrogen ( H) attaches to the other.
[size=18pt]II. Carbohydrates[size=14pt]A. Monosaccharides, Disaccharides, and Polysaccharides[size=14pt]1. Monosaccharides are simple sugars with a carbon backbone of three to seven carbon atoms. [size=14pt]a. Best known sugars have six carbons (hexoses). [size=14pt]1) Glucose and fructose isomers have same formula (C6H12O6) but differ in structure.[size=14pt]2) Glucoseis commonly found in blood of animals; is immediate energy source to cells.[size=14pt]3) Fructose is commonly found in fruit.[size=14pt]4) Shape of molecules is very important in determining how they interact with one another.[size=14pt]2. Ribose and deoxyribose are five-carbon sugars (pentoses); contribute to the backbones of RNA and DNA, respectively.[size=14pt]3. Disaccharides contain two monosaccharides joined by condensation.[size=14pt]a. Sucrose is composed of glucose and fructose and is transported within plants.[size=14pt][size=14pt]b. Lactose is composed of galactose and glucose and is found in milk.[size=14pt]c. Maltose is two glucose molecules; forms in digestive tract of humans during starch digestion.
[size=14pt]B. Polysaccharides Are Varied in Structure and Function[size=14pt]1. Polysaccharides are chains of glucose molecules or modified glucose molecules [size=14pt]a. Starch is straight chain of glucose molecules with few side branches. [size=14pt]b. Glycogen is highly branched polymer of glucose with many side branches; called "animal starch," it is storage carbohydrate in the liver of animals. [size=14pt]c. Cellulose is glucose bonded to form microfibrils; primary constituent of plant cell walls. [size=14pt]d. Chitin is polymer of glucose with amino acid attached to each; it is primary constituent of crabs and related animals like lobsters and insects.[size=18pt]III. Lipids[size=18pt][size=14pt]A. Lipids[size=14pt]1. Lipids are varied in structure.[size=14pt]2. Many are insoluble in water because they lack polar groups.[size=14pt]B. Fats and Oils Are Similar[size=14pt]1. Each fatty acid is a long hydrocarbon chain with a carboxyl (acid) group at one end.[size=14pt]a. Because the carboxyl group is a polar group, fatty acids are soluble in water.[size=14pt]b. Most fatty acids in cells contain 16 to 18 carbon atoms per molecule. [size=14pt]c. Saturated fatty acids have no double bonds between their carbon atoms. (C-C-C-)[size=14pt]d. Unsaturated fatty acids have double bonds in the carbon chain.(C-C-C-C=C-C-) [size=14pt]e. Saturated animal fats are associated with circulatory disorders; plant oils can be substituted for animal fats in the diet.[size=14pt]2. Glycerol is a water-soluble compound with three hydroxyl groups.[size=14pt]3. Triglycerides are glycerol joined to three fatty acids by condensation [size=14pt]4.Fats are triglycerides containing saturated fatty acids (e.g., butter is solid at room temperature).[size=14pt]5. Oils are triglycerides with unsaturated fatty acids (e.g., corn oil is liquid at room temperature).[size=14pt]6. Fats function in long-term energy storage in organisms; store six times the energy as glycogen.[size=14pt]C. Waxes Are Nonpolar Also[size=14pt]1. Waxes area long-chain fatty acid bonded to a long-chain alcohol.[size=14pt]a. Solid at room temperature; have a high melting point; are waterproof and resist degradation.[size=14pt]b. Form protective covering that retards water loss in plants; maintain animal skin and fur.[size=14pt]D. Phospholipids Have a Polar Group[size=14pt]1. Phospholipids are like neutral fats except one fatty acid is replaced by phosphate group or a group with both phosphate and nitrogen [size=14pt] 2.Phosphate group is the polar head: hydrocarbon chain becomes nonpolar tails[size=14pt]3. Phospholipids arrange themselves in a double layer in water, so the polar heads face outward toward water molecules and nonpolar tails face toward each other away from water molecules. [size=14pt]4. This property enables them to form an interface or separation between two solutions (e.g., the interior and exterior of a cell); the plasma membrane is a phospholipid bilayer. [size=14pt]E. Steroids Have Carbon Rings[size=14pt]1. Steroids differ from neutral fats; steroids have a backbone of four fused carbon rings; vary according to attached functional groups.[size=14pt]2. Cholesterol is a precursor of other steroids, including aldosterone and sex hormones. [size=14pt]3. Testosterone is the male sex hormone.[size=14pt]4. Functions vary due primarily to different attached functional groups.IV. Proteins[size=18pt][size=14pt]A. Amino Acids [size=14pt]1. Amino acids are the monomers that condense to form proteins, which are very large molecules with structural and metabolic functions. [size=14pt] 2. Structural proteins include keratin, which makes up hair and nails, and collagen fibers, which support many organs.[size=14pt]3. Myosin and actin proteins make up the bulk of muscle.[size=14pt]4. Enzymes are proteins that act as organic catalysts to speed chemical reactions within cells. [size=14pt]5. Insulin protein is a hormone that regulates glucose content of blood.[size=14pt]6. Hemoglobin transports oxygen in blood.[size=14pt]7. Proteins embedded in the plasma membrane have varied enzymatic and transport functions.[size=14pt]B. Peptide Bonds Join Amino Acids[size=14pt]1. All amino acids contain a carboxyl (acid) group ( COOH) and an amino group ( NH2).[size=14pt]2. Both ionize at normal body pH to produce COO- and NH+; thus, amino acids are hydrophilic.[size=14pt]3. Peptide bond is a covalent bond between amino acids in a peptide; results from condensation reaction.[size=14pt]a. Atoms of a peptide bond share electrons unevenly (oxygen is more electronegative than nitrogen).[size=14pt]b. Polarity of the peptide bond permits hydrogen bonding between parts of a polypeptide. [size=14pt]4. Amino acids differ in nature of R group, ranging from single hydrogen to complicated ring compounds.[size=14pt]a. R group of amino acid cysteine ends with a sulfhydryl ( SH) that serves to connect one chain of amino acids to another by a disulfide bond ( S S).[size=14pt]b. There are 20 different amino acids commonly found in cells.[size=14pt]5. A peptide is two or more amino acids joined together.[size=14pt]a. Polypeptides are chains of many amino acids joined by peptide bonds.[size=14pt]b. Protein may contain more than one polypeptide chain; it can have large numbers of amino acids.[size=14pt]C. Proteins Can Be Denatured[size=14pt]1. Both temperature and pH can change polypeptide shape.[size=14pt]a. Examples: heating egg white causes albumin to congeal; adding acid to milk causes curdling. When such proteins lose their normal configuration, the protein is denatured.[size=14pt]b. Once a protein loses its normal shape, it cannot perform its usual function.[size=14pt]2. The sequence of amino acids, therefore, forecasts the protein's final shape.[size=14pt]D. Proteins Have Levels of Structure[size=14pt]1. Final 3-D shape of a protein determines function of the protein in the organism.[size=14pt]a.Primary structure is sequence of amino acids joined by peptide bonds.[size=14pt]1) Frederick Sanger determined first protein sequence, with hormone insulin, in 1953.[size=14pt]a) First broke insulin into fragments and determined amino acid sequence of fragments.[size=14pt]b) Then determined sequence of the fragments themselves.[size=14pt]c) Required ten years research; modern automated sequencers analyze sequences in hours.[size=14pt]2) Since amino acids differ by R group, proteins differ by a particular sequence of the R groups.[size=14pt]b. Secondary structure results when a polypeptide takes a particular shape.[size=14pt]1) The (alpha) helix was the first pattern discovered by Linus Pauling and Robert Corey.[size=14pt]a) In peptide bonds, oxygen is partially negative, hydrogen is partially positive.[size=14pt]b) Allows hydrogen bonding between the C O of one amino acid and the N H of another.[size=14pt]c) Hydrogen bonding between every fourth amino acid holds spiral shape of a helix.[size=14pt]d) helices covalently bonded by disulfide (S S) linkages between two cysteine amino acids.[size=14pt]2) The sheet was the second pattern discovered.[size=14pt]a) Pleated sheet polypeptides turn back upon themselves; hydrogen bonding occurs between extended lengths.[size=14pt]b) keratin includes keratin of feathers, hooves, claws, beaks, scales, and horns; silk also is protein with sheet secondary structure.[size=14pt]3. Tertiary structure results when proteins of secondary structure are folded, due to various interactions between the R groups of their constituent amino acids[size=14pt]4. Quaternary structure results when two or more polypeptides combine.[size=14pt]1) Hemoglobin is globular protein with a quaternary structure of four polypeptides.[size=14pt]2) Most enzymes have a quaternary structure.V. Nucleic Acids[size=14pt][size=14pt]A. Nucleotides[size=14pt]1. Nucleotides are a molecular complex of three types of molecules: a phosphate (phosphoric acid), a pentose sugar, and a nitrogen-containing base. [size=14pt]2. Nucleotides have metabolic functions in cells.[size=14pt]a. Coenzymes are molecules, which facilitate enzymatic reactions.[size=14pt]b. ATP (adenosine triphosphate) is a nucleotide used to supply energy.[size=14pt]c. Nucleotides also serve as nucleic acid monomers. [size=14pt]B. Nucleic Acids[size=14pt]1. Nucleic acids are huge polymers of nucleotides with very specific functions in cells.[size=14pt]2. DNA (deoxyribonucleic acid) is the nucleic acid whose nucleotide sequence stores the genetic codefor its own replication and for the sequence of amino acids in proteins. [size=14pt]3. RNA (ribonucleic acid) is a single-stranded nucleic acid that translates the genetic code of DNA into the amino acid sequence of proteins.[size=14pt]4. DNA and RNA differ in the following ways:[size=14pt]a. Nucleotides of DNA contain deoxyribose sugar; nucleotides of RNA contain ribose. [size=14pt]b. In RNA, the base uracil occurs instead of the base thymine, as in DNA.[size=14pt]c. DNA is double-stranded with complementary base pairing; RNA is single-stranded.[size=14pt]1) Complementary base pairing occurs where two strands of DNA are held together by hydrogen bonds between purine and pyrimidine bases[size=14pt]2) The number of purine bases always equals the number of pyrimidine bases; called Chargaff's rule[size=14pt]3) Adenine pairs with Thymine & guanine pairs with cytoseine on DNA[size=14pt]4) Guanine & adenine are purines; Cytosine & thymine are pyrimidines[size=14pt]d. Two strands of DNA twist to form a double; RNA generally does not form helices.[size=14pt]C. ATP (Adenosine Triphosphate)[size=14pt]1. ATP (adenosine triphosphate) is a nucleotide of adenosine composed of ribose and adenine.[size=14pt]2. Derives its name from three phosphates attached to the five-carbon portion of the molecule.[size=14pt]3. ATP is a high-energy molecule because the last two unstable phosphate bonds are easily broken.[size=14pt]4. Usually in cells, a terminal phosphate bond is hydrolyzed, leaving ADP (adenosine diphosphate).[size=14pt]5. ATP is used in cells to supply energy for energy-requiring processes (e.g., synthetic reactions); whenever a cell carries out an activity or builds molecules, it "spends" ATP. Summary of Biological Macromolecules: