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Chapter 5: The Structure and Function of Large Biological Molecules

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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).

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Macromolecules Large molecules formed by joining many subunits together. Macro = giant, large Also known as polymers. Ex: Carbs, proteins, lipids, nucleic acids

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Polymers and Monomers Polymermany units bonded together to make a larger macromolecule Poly = many Monomer - A building block of a polymer Mono = one

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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.

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Hydrolysis Reverse of condensation synthesis Hydro - water Lysis - to split Breaks polymers into monomers by adding water

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Four Main Types Of Macromolecules 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic acids

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Carbohydrates Used for fuel, building materials, and receptors. Made of C,H,O General formula is CH 2 O C:H:O ratio is 1:2:1 Monomers joined by glycosidic linkage (covalent bond)

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Types Of Carbohydrates 1. Monosaccharides 2. Disaccharides 3. Polysaccharides

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Monosaccharides Mono - single Saccharide - sugar Simple sugars 3 to 7 carbons Can be in linear or ring forms

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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

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Examples Glucose Galactose Ribose Fructose -ose Names u Word ending is common for many sugar/carbohydrates

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Disaccharides Sugar formed by joining two monosaccharides through a glycosidic linkage Examples: Maltose = glucose + glucose Lactose = glucose + galactose Sucrose = glucose + fructose

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Polysaccharides Many joined simple sugars Used for storage or structure Polymers made of glucose monomers (either or glucose) Examples: Starch Cellulose Glycogen Chitin

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Starch Made of 1-4 linkages of glucose Linkage makes the molecule form a helix Fuel storage in plants

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Cellulose Made of 1-4 linkages of glucose Linkage makes the molecule form a straight line Used for structure in plant cell walls

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Comment Most organisms can digest starch (1- 4 linkage), but very few can digest cellulose (1- 4 linkage) Another example of the link between structure and function

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Glycogen Animal starch Similar to starch, but has more 1-6 linkages or branches Found in the liver and muscle cells

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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

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Monomer: Glucosamine Polymer: Chitin

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Lipids On Your Own First http://www.wisc- online.com/Objects/Vie wObject.aspx?ID=AP132 04 http://www.wisc- online.com/Objects/Vie wObject.aspx?ID=AP132 04 Visit this website and take notes over the material presented; we will go through the ppt after to catch anything missed!

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Lipids Diverse hydrophobic molecules Made of C,H,O No general formula C:O ratio is very high in C

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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 -CH 3 (fat) at the other 2) Glycerol

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AcidFat

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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.

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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 molecules shape

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Fats Differ in which fatty acids are used Used for energy storage, cushions for organs, insulation

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Oils vs. Fats Oil = liquid Fats = solid Most animal fats are saturated FATS (like lard and butter.) Solids Most plant fats are unsaturated fatswe call these OILS (like olive, veggie oil) Liquids

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Nutrition and Diet Diets high in saturated fats cause heart disease Hydrogenated vegetable oil is a product whose unsaturated fats have been converted to saturated fats by adding H

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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.

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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.

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Steroids Lipids with four fused rings. Differ in the functional groups attached to the rings. Examples: cholesterol sex hormones

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Other Lipids Soaps and detergents Waxes Certain pigments Cosmetics

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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

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Uses Of Proteins Structure Enzymes Antibodies Transport Movement Receptors Hormones

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Protein monomers: 20 Amino Acids All have a Carbon with four attachments: -COOH (acid) -NH 2 (amine) -H -R (some other side group)

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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

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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

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Levels of Protein Structure Organizing the polypeptide into its 3-D functional shape. Primary Secondary Tertiary Quaternary

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Primary Sequence of amino acids in the polypeptide chain. Many different sequences are possible with 20 AAs.

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Secondary 3-D structure formed by hydrogen bonding between parts of the peptide backbone. Two main structures: helix pleated sheets

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Tertiary Bonding between the R groups. Examples: hydrophobic interactions Hydrogen bonding ionic bonding Disulfide bridges (covalent bond)

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Quaternary When two or more polypeptides unite to form a functional protein. Example: hemoglobin

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Is Protein Structure Important?

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Denaturing Of A Protein Events that cause a protein to lose structure (and function). Example: pH shifts (confuses chemical interactions) high salt concentrations (confuses chemical interactions) heat (usually renders proteins inactive)

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Denaturing, cont. Ex: white of an egg turns white (denatured protein due to heat) Ex: why extreme temps are so deadly to people/animals

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Nucleic Acids Informational polymers Pass genetic info from parent to offspring Made of C,H,O,N and P No general formula Examples: DNA and RNA

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Nucleic Acids Polymers of nucleotides Called polynucleotides Nucleotides have three parts: nitrogenous base pentose sugar phosphate

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Nitrogenous Bases Rings of C and N The N atoms tend to take up H + (base)-b/c of neg charge Two types: Pyrimidines (single ring)-C,T,U Purines (double rings)-A,G

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Pentose Sugar 5-C sugar Ribose - RNA Deoxyribose DNA RNA and DNA differ in an OH group on the 3 rd carbon

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DNA Deoxyribonucleic Acid Makes up genes Genetic information source for most life Found inside nucleus Copied during cell cycle (Interphase)

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RNA Ribonucleic Acid. Structure and protein synthesis. Genetic information for a few viruses only. Found in Nucleus and near ribosomes in cytoplasm Three types Messenger (m) Ribosomal (r) Transfer (t) Contains: Uracil

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MacromoleculeMonomerPolymer CarbohydrateMonosaccharideDisacc, Oligio, Polysacc ProteinAmino acidPolypeptide chain Nucleic acidNucleotide DNA, RNA (Polynucleotide) LipidsFatty acid, glycerolFats, waxes, oils, steroids

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Summary Recognize how dehydration synthesis can be used to build polymers from monomers. Recognize how hydrolysis can be used to break down polymers into monomers. Identify the elemental composition, general formula, types and uses of carbohydrates. Identify the elemental composition, types and uses of lipids. Identify the elemental composition, levels of structure and uses of proteins. Identify the elemental composition and general uses of nucleic acids.