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Chapter 3 Vocabulary: Macromolecule Monomer Dehydration reactions Hydrolysis reactions ATP NAD and FAD Motifs Domains Carbohydrates Nucleic acids Proteins Lipids Outline 3.1 Carbon 6 elements make up macromolecules: C, H, N, O, P, S (arranged like this they resemble the word chin ups) C is central to macromolecules because of its chemistry Functional groups: Hydroxyl (polar, found in all macromolecules, can hydrogen bond) Carbonyl (polar, found in carbs and nucleic acids, can hydrogen bond) Carboxyl (polar, found in proteins and lipids, acidic) Amino (polar, found in proteins and nucleic acids, weak base) Sulfhydryl (found in proteins, stabilizes them) Phosphate (polar, found in nucleic acids, energy storing bonds) Methyl (non-polar, hydrophobic, found in proteins) Spending a few minutes on these functional groups helps them understand the macromolecules better and allows you to revisit bonding. Monomers Polymers Macromolecule – large organic molecules made of covalently bonded repeating subunits called monomers Dehydration builds Hydrolysis breaks I show a generic example like the one below before showing the bonding between actual monomers H-monomer-OH H-monomer-OH - H2O H-monomer—monomer-OH 3.2 Carbohydrates Major fuel molecule (used as structural material and energy source) Formula (CH2O)N Monomer is monosaccharide Very versatile Used as monosaccharide (ex. Glucose, fructose, galactose, ribose, deoxyribose) Disaccharides (ex. Lactose, Sucrose, maltose) Short chain carbohydrates (used as markers on cell – allow cell to cell communication, provide mechanism for immune response, self-recognition) Complex carbohydrates 1)glycogen – energy storage in animals, made in the liver when there’s too much glucose in the blood. Can be broken down later into glucose and used as energy. Keeps blood glucose levels stable. 2)starch – energy storage in plants Glycogen and starch are easily degraded and can be used when necessary for energy. 3) chitin – structural storage in animals (ex. shrimp shells, cockroach crunch) 4) cellulose – structural storage in plants Chitin and cellulose are designed to be strong and unbreakable. Insect shells provide protection. In plants the cellulose provides rigidity to plants blowing in the wind. Cellulose cannot be digested by humans because we lack the enzymes necessary to break the bonds. Termites and cows have symbiotic bacteria living in their guts that have the enzymes necessary to break the bonds in cellulose. Starch has alpha linkages that form valleys. Cellulose has beta linkages that form mountains. Our enzymes can cross the valley, but not climb the mountain. This is why there are calories in potatoes, but not lettuce. 3.3 Nucleic Acids Two main types: DNA and RNA DNA carries the genetic code RNA working nucleic acid – responsible for reading DNA and building proteins Function also as energy molecules (ATP) and Electron carriers (NADH, FADH2) Nucleic acids are made of nucleotides Nucleotides have three parts: Phosphate group Nitrogenous base (A, T, C, G, U) Pentose sugar (ribose or deoxyribose) DNA Double helix Covalent phosphodiester bonds link the sugar of 1 nucleotide to the PO4- group of another nucleotide by dehydration synthesis Two strands are held together by weak Hydrogen bonds between complimentary bases A=T C=G The complimentary base pairs have to do with the shape of the bases A and G are purines and have a double ring structure T and C are pyrimidines and have a single ring structure Bases are at the center of the double stranded molecule and essentially form the rungs of the ladder RNA Not as stable, short-term molecule Working nucleic acid Single stranded Uses A, U, C, G 3 types: mRNA tRNA rRNA Central Dogma of Biology DNARNAproteins Transcription translation 3.4 Proteins Function as work force of the cell Proteins made of amino acids (NH3 – C (H, R) – COOH) 20 amino acids The physical expression of DNA Large and complicated molecules – shape is integral to function 4 levels of structure: Primary – string of amino acids Secondary – folding due to Hydrogen bonds attracting amino acids (can cause standard shapes of alpha helix, or beta sheet) Tertiary – folding due to hydrophobic exclusion, ionic bonds and disulfide bonds (bonds between functional groups with S). Quaternary – bond to another structure Shape is more important than linear sequence (Ex. hammer and screw driver) Motif Domains Denaturation Functions: Act as enzymes (catalysts for chemical reactions) Involved in membrane transport Involved in most types of movement (muscle contractions, flagella, actin and myosin) Serve as messengers in the body (hormones such as insulin, growth hormones) Structural molecules (keratin protein in hair, nails, found in cartilage and ligaments, collagen) Cellular transport (hemoglobin carries O2 in the blood) Defense (Ab in the immune system and venom in snakes) 3. 5 Lipids Oils, waxes, fats Non-polar hydrophobic group Functional group is hydrocarbon chains Can be saturated (all possible locations have H on them, solid at room temp because densely packed) or unsaturated (kinks form in the chain due to the presence of double bonds, liquid at room temperature because cannot order themselves as strenuously). Trans fats have double bonds, but resemble saturated fats. Functions of lipids: Triglycerides are a large energy storage molecules (stored as fat in animals, provides a huge amount of energy or insulation or cushion) Waterproof (waxy coatings on plants protect them from drying out, wax coatings on bird wings) Hormones (chemical messengers that carry signals) Vitamins A (vision), D (calcium absorption), E (antioxidant to protect cells), K (helps form blood clots) Pigments that gather energy during photosynthesis Phospholipids are important components of cell membrane. Has a polar head and a non-polar fatty acid tail. Steroids (unique chemical structures found in cell membranes. Some hormones are a type of steroids – chemical messengers) Waxes that protect, lubricate and lend pliability to hair and skin. Also beeswax used to build houses. Cholesterol – important membrane protein that provides rigidity and serves as a pre-cursor to other sterols and hormones. 75% of cholesterol is make in the liver 25% comes from diet LDL (low lipo-density) cholesterol is “bad”. It is found in saturated and trans fats. It clogs arteries and leads to heart attack. HDL (high lipo-density) cholesterol is “good”. It carries “bad” cholesterol to the liver for disposal. There is a lot of chemistry in this chapter! The focus should NOT be on the chemistry; it should be on the macromolecules. The chemistry of carbon is important (ability to make 4 bonds, how saturated and unsaturated fats satisfy carbon’s octet, why functional groups confer properties etc). The biochemistry of isomers is NOT important. The chemistry of bonding is important (covalent bonds between monomers, hydrogen bonds in proteins and nucleic acids, etc.). The chemistry of molecules is important (polarity of lipids and how this affects their behavior). What students need to know about each macromolecule are basically the monomer, the structure of the monomer, the function of each macromolecule and examples of each.