Biology 107 Macromolecules I September 2, 2005
Macromolecules I Student Objectives:As a result of this lecture and the assigned reading, you should understand the following: 1.The four major types of organic macromolecules are: carbohydrates, lipids, proteins, and nucleic acids. 2.Carbohydrates generally have molecular formulas that are some multiple of CH 2 O, and carbohydrates range from single small sugar molecules (monosaccharides) to long polymers of sugar monomers (polysaccharides). a.Structure - Monosaccharides have two or more -OH groups and either an aldehyde or a ketone group. Polysaccharides may be straight or branched molecules of hundreds or thousands of sugar monomers. Some sugars are highly negatively charged because they are commonly sulfated (SO 3- ) or because they contain a carboxyl group (COO - ).
Macromolecules I b.Functions - energy source, recognition or signaling, and/or structural. 3.Lipids consist mainly of C and H atoms linked by nonpolar covalent bonds; consequently, lipids are not attracted to polar water molecules, and lipids are hydrophobic. a.Structure – Fats and oils are large lipids made from glycerol and fatty acids. Triglyceride fats consist of three (3) fatty acid chains hooked to a glycerol molecule. For saturated fats, every C atom of the carbon skeleton (except the carboxyl carbon) carries 2 H atoms (the maximum number of hydrogens). In contrast, unsaturated fats contain double bonds and less than the maximum number of hydrogens possible.
Macromolecules I Phospholipids, the major components of cellular membranes, are structurally similar to fats except they contain a phosphate group and only 2 fatty acid chains attached to the glycerol. Steroids are lipids with the carbon chain bent to form fused rings. Cholesterol is a common substance in animal cell membranes. Animal cells also use cholesterol as a precursor for making other steroids, including male and female sex hormones. b. Functions - energy storage, membrane structure, hormone signaling, and/or insulation.
Four Main Types of Macromolecules
Common Carbohydrates Classified by Number of Carbons
Examples of Hexose Isomers
Examples of Linear Compared to Ring Forms of Carbohydrate
Disaccharides
Polysaccharides Examples: Starch – Fxn as storage form of energy Cellulose – Fxn as structural material
Storage Polysaccharides Starch and glycogen are storage polysaccarides in animals and plants. Polymers of glucose. Reserve fuel.Starch and glycogen are storage polysaccarides in animals and plants. Polymers of glucose. Reserve fuel. Starch (plant cells) is an isomer of cellulose with -glycosidic bonds. Unbranched (amylose) and branched (amylopectin).Starch (plant cells) is an isomer of cellulose with -glycosidic bonds. Unbranched (amylose) and branched (amylopectin). Glycogen (animal cells) is similar structure to starch but with ß - glycosidic bonds and highly branched. Degraded from end, so branches allow rapid degradation.Glycogen (animal cells) is similar structure to starch but with ß - glycosidic bonds and highly branched. Degraded from end, so branches allow rapid degradation. Starch
Glycogen Large branched polymer Most glucose units linked by -1,4 glycosidic bonds Branches formed by -1,6 glycosidic bonds every ~10 glucose units
Structural Oligosaccharides Cellulose - plant cell walls, load bearing. Fifty percent of carbon in biosphere. May have up to 15,000 glucose residues Chitin - exoskeletons (crustaceans, insects), cell walls of fungi and algae.
Lipids - Fats
Triglyceride Fats
Saturated Fatty Acid Chains
Unsaturated Fatty Acid Chains
Comparison of Saturated and Unsaturated Fatty Acid Chains
Sources of Saturated and Unsaturated Fatty Acids
Phospholipids
Phospholipids in Water
Structure of Phospholipids and Steroids
Examples of Lipids Other Than Phospholipids or Steroids
Different Types of Macromolecules May be Covalently Linked (e.g., Glycolipids)