Chapter 5: The Structure and Function ofLarge Biological Molecules
Essential Knowledge • 3.a.1 – DNA, and in some cases RNA, is the primary source of heritable information (5.5). • 4.a.1 – The subcomponents of biological molecules and their sequence determine the properties of that molecule (5.1-5.5). • 4.b.1 – Interactions between molecules affect their structure and function (5.4). • 4.c.1 – Variation in molecular units provides cells with a wider range of functions (5.1-5.5).
Macromolecules • Large molecules formed by joining many subunits together. • Macro = giant, large • Also known as “polymers”. • Ex: Carbs, proteins, lipids, nucleic acids
Polymers and Monomers • Polymer—many units bonded together to make a larger macromolecule • Poly = many • Monomer - A building block of a polymer • Mono = one
Condensation Synthesis or Dehydration Synthesis • The chemical reaction that joins monomers into polymers • Covalent bonds are formed by the removal of a water molecule between the monomers.
Hydrolysis • Reverse of condensation synthesis • Hydro - water • Lysis - to split • Breaks polymers into monomers by adding water
Four Main Types Of Macromolecules • Carbohydrates • Lipids • Proteins • Nucleic acids
Carbohydrates • Used for fuel, building materials, and receptors. • Made of C,H,O • General formula is CH2O • C:H:O ratio is 1:2:1 • Monomers joined by glycosidic linkage (covalent bond)
Types Of Carbohydrates • Monosaccharides • Disaccharides • Polysaccharides
Monosaccharides • Mono - single • Saccharide - sugar • Simple sugars • 3 to 7 carbons • Can be in linear or ring forms
Monosaccharides • Can be “Aldoses” or “Ketoses” depending on the location of the carbonyl group. • Aldose – end of chain • Ketose – middle of chain • Notice: names of end in -ose
Examples • Glucose • Galactose • Ribose • Fructose -ose Names • Word ending is common for many sugar/carbohydrates
Disaccharides • Sugar formed by joining two monosaccharides through a “glycosidic linkage” • Examples: • Maltose = glucose + glucose • Lactose = glucose + galactose • Sucrose = glucose + fructose
Polysaccharides • Many joined simple sugars • Used for storage or structure • Polymers made of glucose monomers (either a or b glucose) • Examples: • Starch • Cellulose • Glycogen • Chitin
Starch • Made of 1-4 linkages of a glucose • Linkage makes the molecule form a helix • Fuel storage in plants
Cellulose • Made of 1-4 linkages of b glucose • Linkage makes the molecule form a straight line • Used for structure in plant cell walls
Comment • Most organisms can digest starch (1- 4 a linkage), but very few can digest cellulose (1- 4 b linkage) • Another example of the link between structure and function
Glycogen • “Animal starch” • Similar to starch, but has more 1-6 linkages or branches • Found in the liver and muscle cells
Chitin • Used by insects, spiders, crustaceans to build exoskeletons • Also found in cell walls • Differs from cellulose – chitin has nitrogen branch connected to glucose monomer
Polymer: Chitin Monomer: Glucosamine
Lipids – On Your Own First • http://www.wisc-online.com/Objects/ViewObject.aspx?ID=AP13204 • Visit this website and take notes over the material presented; we will go through the ppt after to catch anything missed!
Lipids • Diverse hydrophobic molecules • Made of C,H,O • No general formula • C:O ratio is very high in C
Lipid monomers • Made of two kinds of smaller monomers. • 1) Fatty Acids • A long carbon chain (12-18 C) with a -COOH (acid) on one end and a -CH3 (fat) at the other • 2) Glycerol
Neutral Fats or Triacylglycerols • Three fatty acids joined to one glycerol. • Joined by an “ester” linkage between the -COOH of the fatty acid and the -OH of the alcohol.
Saturated vs. Unsaturated Fats • Saturated - no double bonds. • Unsaturated - one or more C=C bonds. • Can accept more hydrogens • Double bonds cause “kinks” in the molecule’s shape
Fats • Differ in which fatty acids are used • Used for energy storage, cushions for organs, insulation
Oils vs. Fats • Oil = liquid • Fats = solid • Most animal fats are saturated FATS (like lard and butter.) • Solids • Most plant fats are unsaturated fats—we call these OILS (like olive, veggie oil) • Liquids
Nutrition and Diet • Diets high in saturated fats cause heart disease • Hydrogenated vegetable oil is a product whose unsaturated fatshave been converted to saturated fats by adding H
Question??? • Which has more energy, a kg of fat (lipid) or a kg of starch (carb)? • Fat!!!!! There are more C-H bonds which provide more energy per mass.
Phospholipids • Similar to fats, but have only two fatty acids. • The third -OH of glycerol is joined to a phosphate containing molecule. • Phospholipids have a hydrophobic tail, but a hydrophilic head. • Self-assembles into micells or bilayers, an important part of cell membranes.
Steroids • Lipids with four fused rings. • Differ in the functional groups attached to the rings. • Examples: • cholesterol • sex hormones
Other Lipids… • Soaps and detergents • Waxes • Certain pigments • Cosmetics
Proteins • The molecular tools of the cell • Made of C,H,O,N, and sometimes S • No general formula • Polypeptide chains of Amino Acids linked by peptide bonds
Uses Of Proteins • Structure • Enzymes • Antibodies • Transport • Movement • Receptors • Hormones
Protein monomers: 20 Amino Acids • All have a Carbon with four attachments: • -COOH (acid) • -NH2 (amine) • -H • -R (some other side group)
Amino acid “R” groups • The properties of the R groups determine the properties of the protein. • 20 different kinds: • Nonpolar - 9 AA • Polar - 6 AA • Electrically Charged • Acidic - 2 AA • Basic - 3 AA
Polypeptide Chains • Formed by dehydration synthesis between the carboxyl group of one AA and the amino group of the second AA. • Produce an backbone of: (N-C-C)X
Levels of Protein Structure • Organizing the polypeptide into its 3-D functional shape. • Primary • Secondary • Tertiary • Quaternary
Primary • Sequence of amino acids in the polypeptide chain. • Many different sequences are possible with 20 AAs.
Secondary • 3-D structure formed by hydrogen bonding between parts of the peptide backbone. • Two main structures: • a helix • pleated sheets