I. Polymers & Macromolecules Figure 1: Polymers Polymer: Macromolecule: Figure 2: Polymerization via Dehydration Synthesis 1
Dehydration Synthesis: Figure 3: Depolymerization via Hydrolysis Hydrolysis: II. Organic Macromolecules Class I Macromolecules: Carbohydrates Figure 4: General Structure General characteristics of carbohydrates include the following: a) Ring structure composed of C,H,& O in a ratio of nearly 1:2:1 (ratio deviates in more complex carbs) b) Names of carbohydrates generally end in the suffix -OSE 2
Carbohydrates: Monosaccharides Figure 4.1: Monosaccharrides Monosaccharides: a) Monosaccharides are sweet tasting sugars (interact with sweet taste buds). b) Glucose is the most abundant monosaccharide & is thus the major nutrient (energy source) for cells. Chemical Testing for Monosaccharides Figure 4.2: Benedicts Solution Blue Green Yellow Orange Red Benedict s Solution is blue in color can be used to test for the presence of some monosaccharides. A positive test for the presence of monosaccharides is a brick red by product when a mixture thought to contain simple sugars is heated. Carbohydrates: Disaccharides Figure 5: Disaccharides (Sucrose) Glucose Fructose Sucrose *As a result of the dehydration synthesis reaction between monosaccharides (glucose & fructose) a covalent bond called a Glycosidic Bond is formed to produce the dissacharide (sucrose). 3
Disaccharides: a) Like monosaccharides, disaccharides are sweet-tasting sugars. Carbohydrates: Polysaccharides Figure 6: Polysaccharides Polysaccharides: a) Polysaccharides are NOT sweet-tasting sugars (not compatible with sweet taste buds) Figure 6.1: Storage Polysaccharides (Starch) Starches are moderately branched molecules used by plants to store excess glucose produced by photosynthesis. Can be quickly broken down (hydrolyzed) back into glucose for cellular energy when needed. 4
Chemical Testing for Starch Figure 6.2: Lugol s Iodine Test Lugol s Iodine (I) Solution is amber (yellow-brown) in color & is used to test for the presence of starch. In the presence of iodine, starch will produce a blue-black color. If not present, the iodine solution will remain amber in color. Figure 6.3: Storage Polysaccharides (Glycogen) Glycogen is a heavily branched molecule synthesized in liver cells from excess glucose following digestion. Stored in both liver & muscle cells until needed. Storage Polysaccharide: 5
Figure 6.4: Structural Polysaccharides (Cellulose) Cellulose is an unbranched molecule & a component of plant cell walls consisting of glucose subunits. Form fibers that strengthen cell walls. Not easily digested most organisms because of a lack of enzymes that hydrolyze the bonds between the glucose subunits. Figure 6.5: Structural Polysaccharides (Chitin) Found in arthropods (insect & crustacean) exoskeletons & fungi cell walls. Chitin forms tough structures because, like cellulose, its molecules it can be arranged into fibers. Structural Polysaccharide: 6
Class II Macromolecules: Lipids Figure 7: Lipids Classes Consist of a diverse array of molecules including fats, phospholipids, steroids, & waxes. Are not considered polymers because they are not composed of similar subunits. Despite the differences among types of lipids, they all share the property of being nonpolar & insoluble in water. Lipid: Lipids: Fats/Triglycerides Figure 8: Fat Structure Consist of 1 GLYCEROL MOLECULE & 3 FATTY ACIDS. At one end of each fatty acid is a head consisting of a carboxyl group (acidic) followed by a long carbon tail. The nonpolar C-H bonds in the fatty acid tails make fat molecules HYDROPHOBIC. 7
Fats form via dehydration synthesis whereby the OH groups of glycerol react COVALENTLY with the carboxyl groups of the fatty acids; each reaction forms an Ester Bond & results in the release one water molecule (3 total). Fats/Triglycerides: Figure 8.1: Saturated Fats Figure 8.2: Unsaturated Fats 8
Lipids: Phospholipids Figure 9: Phospholipid Have both hydrophobic (fatty acid tails) & hydrophilic (phosphate head) regions. Thus in water, phospholipids form droplets where the hydrophilic heads contact the water & the hydrophobic tails are restricted to the water-free interior. Due to this behavior, phospholipids are a major component of biological membranes. Phospholipids: Lipids: Steroids Figure 10: Steroids (Cholesterol) Steroids: a) Cholesterol is the simplest of all steroids & is the building block of more complex steroid molecules. 9
Figure 10.1: Steroids (Testosterone & Estrogen) Testosterone is a steroid that promotes the development of secondary sex characteristics in males during puberty, while Estrogen has a similar effect in females. Both steroids are produced from the modification of cholesterol. Waxes are lipids that form between alcohols & fatty acids & are highly variable in structure. Both animals & plants produce waxes; in the case of plants, these waxes prevent water loss from body tissue that may result in the plant drying out & dying. Chemical Testing for Lipids Lipids do not dissolve in water, but DO dissolve in ethanol. Shake some of the test sample with ethanol. Pour the liquid into a test tube of water, leaving any undissolved substances behind. If there are lipids dissolved in the ethanol, they will come out of solution in water, forming a cloudy white film. Class III Macromolecules: Proteins Figure 11: Amino Acids (Monomers of Proteins) Proteins are the most complex of all organic macromolecules & contain carbon, hydrogen, oxygen, & nitrogen. The building blocks of proteins are Amino Acids. All 20 amino acids consist of an amino group (-NH 2 ), carboxyl group (-COOH), & side chain attached to a central carbon. It is the functional unit of the side chain (R) that makes all amino acids unique. Names of most proteins end in the suffix IN or ASE (if the protein is an enzyme) 10
Proteins: Figure 11.1: Peptide Synthesis (Dipeptide) When the COOH group of one amino acid is adjacent to the NH 2 group of another, an enzyme will join them via dehydration synthesis to form a Peptide Bond. The resulting molecule is known as a Dipeptide. As many more amino acids are added, a long Polypeptide chain is formed. All polypeptide chains have a COOH (carboxyl group) at one end & an NH 2 (amino group) at the other: Once formed, a polypeptide chain begins to fold in a specific way dictated by its unique sequence of amino acids to form a Protein. Proteins are 3-D polypeptides that can perform a specific function within the cell. Three to four levels of folding are often observed within protein molecules 11
Figure 11.2: Levels of Protein Structure Primary Structure: represents the unique amino acid sequence of a polypeptide involves peptide bonds only. Secondary Structure: represents coiled or folded segments of the polypeptide chain established by H-bonds between amino & carboxyl groups. Tertiary Structure: is the folding of the polypeptide through the interaction of adjacent R-Groups. This bonding can result in the polypeptide taking on a 3-D shape, enabling it to become fully functional. 12
Quaternary Structure: represents the most complex protein structure that forms when two or more polypeptide chains of tertiary structure join to form a functional protein. NOT ALL PROTEINS REACH THIS LEVEL! The same types of interactions that produce tertiary structure also contribute to quaternary structure. Figure 11.3: Specificity of Proteins Protein Specificity: a) Protein Binding Sites arise due to the specific manner in which polypeptides fold to achieve either tertiary or quaternary structure. b) The shape of the binding site is very specific & allows proteins to only recognize & bind to a particular class of molecule or Substrate. Chemical Test for Proteins The presence of protein in solution can be indicated by the use of Biuret Solution. In the presence of protein, biuret turns from blue to pink in color. 13
Figure 11.4: Protein Denaturation Denaturation: a) The denaturation of a protein can be initiated by extreme heat (NOT cold!!), ph, physical stress, & salt concentrations. Class IV Macromolecules: Nucleic Acids Figure 12: Nucleotide (Building Block of DNA, RNA) The units that comprise nucleic acids are called Nucleotides, which consist of a 5-sided sugar, a phosphate group, & a nitrogenous base. Bases can be classified as Purines or Pyrimidines based on their structures: a) Purine Nitrogenous Bases: consist of a 5-sided + 6-sided ring & include Adenine (A) & Guanine (G) b) Pyrimidine Nitrogenous Bases: consist of a 6-sided ring & include Thymine (T), Cytosine (C), & Uracil (U) DNA nucleotides lack an OH on the 2 -carbon of the sugar (deoxyribose). In addition, DNA nucleotides may bear the bases A, C, G, or T on the 1 -carbon whereas RNA nucleotides may bear A, C, G, or U. DNA is also double stranded & contains information for the production of proteins. RNA is single stranded & is involved in relaying genetic information from DNA to regions of the cell responsible for protein production. 14
Figure 12.1: DNA vs RNA Structure 15