9/23/2011 Objective: Describe properties of each of the four classes of macromolecule Warm-Up: Write down two questions you have from this week.

Properties of Biological Macromolecules 23 September 2011

Organic Molecules Molecules containing carbon are called organic Exception: Carbon monoxide and carbon dioxide are not organic Note: Water is inorganic! Carbon is unique because it can make 4 covalent bonds This means that carbon can form rings, chains, and branching molecules Many different structures = many different functions These large, organic molecules are called macromolecules 30% of your cells’ cytoplasm is organic material

Polymers and Monomers The biological macromolecules are polymers This means that they are large molecules constructed of repeating smaller units The smaller units—the building blocks—are called monomers Keep in mind that “polymer” is a generic category; carbs, proteins, etc. are specific examples of polymers “Monomer” is also a generic category; amino acids, monosaccharides, and nucleotides are specific monomers

Carbohydrates Made of monosaccharides In animals, used primarily for short-term energy Carbon-carbon bonds store energy Breaking those bonds releases energy In a long chain of carbons, there is a lot of energy! Cells use glucose for energy In animals, excess glucose is stored as glycogen in the liver In plants, excess glucose is stored as starch Cellulose, a carbohydrate made of very long glucose chains, provides structure to cell walls

Glucose

Lipids Long-term energy storage and cell membranes Triglycerides A special class of lipids called phospholipids make up the cell membrane Triglycerides Simple fats made up of one molecule of glycerol and three fatty acids There are many different fatty acids Fats have different properties depending on the fatty acids present Unsaturated fatty acids are liquid at room temperature Saturated fatty acids are solid

Proteins There are 20 different amino acids Each protein has a unique amino acid sequence The amino acid sequence is referred to as the protein’s primary structure Each amino acid has a unique chemical structure, giving it unique chemical characteristics The bond between two amino acids is called a peptide bond A chain of amino acids is therefore called a polypeptide Long polypeptide chains fold into proteins

Proteins (cont) A chain of amino acids will “fold” and “twist” because of interactions between the chemical group This is called secondary structure Amino acids that are hydrophobic will “fold” to the inside of the chain The organized chains of amino acids will continue to fold into a more complex three-dimensional shape The protein’s three-dimensional shape is its tertiary structure A PROTEIN’S 3D SHAPE DETERMINES ITS FUNCTION Some proteins have a quaternary structure, which occurs when two or more tertiary forms interact

Nucleic Acids Nucleotides have three parts: a sugar, a phosphate group, and a nitrogen base Each nucleotide has a unique nitrogen base Different nucleic acids use different sugars DNA uses deoxyribose RNA uses ribose In double-stranded DNA, there is hydrogen bonding between nitrogen bases that holds the two strands together

Dehydration Synthesis When a peptide bond forms between two amino acids, a molecule of water is released from the two amino acids The same thing happens when two molecules of glucose bond, and when a fatty acid bonds to glycerol Dehydration = loss of water Synthesis = to make When these bonds are made, water is “lost” from the molecules