Food, glorious food • All about biological molecules
Four basic biological molecules • Carbohydrates • Proteins • Lipids • Nucleic Acids (Which we will look at later)
Monomers and Polymers “Mono” means “one.” “Poly” means “many.” Large biological molecules are made up of smaller ones.
Carbohydrates • Sugars: the basic building blocks of complex carbohydrates. • Polysaccharides: long chains of sugars. Some include: • starch • cellulose (“fiber”) • glycogen
Sugars • Sugars are the simplest carbohydrates. • Sugars can be single-ring (monosaccharides) or double-ring (disaccharides).
Glucose, a monosaccharide • Notice the ring-shaped structure. • Glucose is an energy source for all eukaryotic organisms. Your brain uses 30% of all glucose you consume.
Maltose, a disaccharide Notice the two-ring structure. Anything look familiar? Maltose is made up of two glucose molecules.
Forming Maltose Notice that we’re about to lose an H from one glucose and an OH from the other. Both glucose molecules will link to one oxygen atom. Because water (HOH) is lost, this is called dehydration synthesis.
Sucrose, a disaccharide Note the components: glucose and fructose.
Starch • Starch is a polysaccharide • A starch molecule is a long chain of hundreds of glucose molecules.
Starch Here is a model of starch (also called amylose). Notice that dehydration synthesis happens here, also.
Cellulose Here is a model of cellulose. What do you see here that was different in starch? The difference is small, but crucial.
Starch and Cellulose See it now? That’s all it takes to make starch digestible and cellulose (“fiber”) indigestible to humans.
Lipids • Lipids are fats, waxes, and oils. • Lipids are made up of fatty acid chains and glycerine molecules.
Lipid molecule structure The head of a lipid molecule may be polar, attracting water. Fatty acids, being non-polar, repel water.
Saturated vs. Unsaturated A side-by-side comparison of a saturated (hydrogenated) and a monounsaturated fatty acid.
Saturated vs. Unsaturated • Saturated fatty acids pack together neatly, making fats that are solid at room temperature.
Saturated vs. Unsaturated • The bent chains of unsaturated fats do not fit together neatly. • Unsaturated fats are liquid at room temperature.
Thinking question • Shortening and margarine labels often brag that their products are made with healthy, unsaturated vegetable oils. So why are they solid at room temperature? Hint: Check the ingredients. What does “hydrogenated” mean?
Proteins • Egg whites are made up of a protein called albumin. • Like all proteins, albumin is composed of thousands of amino acids.
Protein • Proteins are polymers. • Proteins are long chains of amino acids.
Amino Acids • An amino acid has three critical parts: • amine group • carboxyl (acid) group • R group (side chain)
Proteins As you can see, it takes many, many amino acids to make up a protein such as albumin.
Proteins Amino acids link together with peptide bonds. As you can see, peptide bonding is a type of dehydration synthesis.
Two types of proteins: • Structural proteins are used to build fibers and tissues. • Enzymatic proteins take part in chemical processes.
Recap • Starches and other polysaccharides are long chains of sugars. • Proteins are made up of amino acids. • Lipids (fats, waxes, oils) are made up of fatty acids and glycerol molecules.