ORGANIC BASIS OF LIFE Chapter 3

Organic Compounds Carbon based molecules – Form covalent bonds Review electron shell model – Hydrocarbons are nonpolar, containing only C and H Dependent upon – Structural size CH 4, C 6 O 12 H 6, CO 2 – Shape Can form chains, branches, or rings Isomers: same chemical formula, but different atomic arrangement – Functional group Creates specific structural and functional properties

Isomers C 4 H 10 C4H8C4H8

Functional Groups Be able to recognize/identify each Hydroxyl Carboxyl Amino Phosphate Other groups, but don’t need to know Carbohydrates Lipids Proteins DNA, ATP

Functional Groups in Action

The Importance of Carbon All living organisms based significantly on carbon Creates a large diversity of biological molecules – 4 main classes* Carbohydrates Lipids Proteins Nucleic Acids – Distinguishes living from nonliving matter All these molecules are examples of emergent properties * important to know how these are made, stored, and destroyed

Biological Molecule Building Blocks Monomers: small repeating units – Universal, similar in all forms of life Polymers: chains of monomers – DNA is composed of 4 monomers (nucleotides) Variation based on arrangement – Proteins from 20 different amino acids (AA’s) Variation distinguishes within and between species

Making and Breaking Macromolecules Dehydration reaction Links monomers Loss of water for each monomer added Forms a covalent bond Hydrolysis reaction Breaks polymers Addition of water for each broken bond

Carbohydrates Range from sugar in beverages to starch in foods Basic composition – CH 2 O (1:2:1 ratio) – Have - OH and C=O – End in ‘-ose’ – Hydrophilic (means what?; why?) Types – Monosaccharides – Disaccharides – Polysaccharides Energy storage

Monosaccharides Simple sugars (monomers) – Glucose and fructose Isomers (means what?) Fructose is sweeter – Galactose Main fuel for cells – Unused get incorporated into more complex sugars Most 3-7 carbon atoms long

Disaccharides 2 monosaccharides joined by a covalent (glycosidic) bond – Dehydration reaction Maltose – glucose + glucose – Whoppers©, malts, beer Sucrose – Glucose + fructose – Table sugar – Plant sap Lactose – galactose + glucose

Polysaccharides Insoluble Storage – Glycogen in animals (short term) – Starch in plants Structure – Cellulose in plant cell walls Not always digestable – Chitin in insect and crustacean exoskeletons Protection and nutrients for animals Surgical thread

Lipids Not true polymers Long term energy storage Insoluble – Salad dressing (o & v) – Bird feathers (repellent beads) 3 types – Triglycerides (fats) Saturated are solid at room temp – Animal fats Unsaturated are liquids at room temp – Plant fats (oils) – Phospholipids – Steroids Sex hormones Synthetic forms

Proteins Polypeptide chain folded and coiled into a specific shape – Polymer combo of 20 amino acids (AA’s) – Variation determines structure and function Multiple types – Enzymes – speed chemical reactions – Structural – hair and connective tissue – Signal – hormones for communication Altered by denaturation – Changes in [salt], pH, or excessive heat – Danger of high fevers

Amino Acids Common structure varied by side chain (R) Properties determined by R group – Hydrophilic or hydrophobic – (+) or (-) charge Dehydration reaction joins AA’s – Forms peptide bonds – Dipeptide = 2 AA’s joined – Polypeptide = multiple AA’s Hydrolysis reverses – Eating food Polypeptides ≠ a protein

Protein Structure Primary (1°) – Sequence of AA’s determined by DNA Secondary (2°) – Folds ( β- pleated sheet) and coils (α-helix) from H-bonding Tertiaty (3°) – 3D shape of polypeptide – Globular or fibrous Quartenary (4°) – 2 + associated polypeptide chains Single change  shape change  functional change

Nucleic Acids DNA (deoxyribonucleic acid) Genetic code Nucleotides – Deoxyribose sugar – Phosphate group – 4 nitrogenous bases Adenine (A) Cytosine (C) Guanine (G) Thymine (T) Double stranded – Hydrogen bonds A & T C & G RNA (ribonucleic acid) Protein synthesis Nucleotides – Ribose sugar – Phosphate group – 4 nitrogenous bases Adenine (A) Cytosine (C) Guanine (G) Uracil (U) Single stranded

Basis For Life and Individuality Primary structure of polypeptides determined by genes, discrete units of inheritance Genes are sequences of DNA – DNA determined by organization of 4 nucleotides DNA RNA proteins (polypeptides) – Central dogma of molecular biology Genes are the blueprint for the living organism seen transcribedtranslated

Review of Biological Macromolecules Macromolecule Carbohydrates Proteins Nucleic acids Lipids* Monomer/Polymer(s)/E.g. monosaccharide/ ?/ ? ?/ polypeptide/ ? ?/ nucleic acids/ ? glycerol and FA’s/ ?/ ?* * Not true monomer/polymer match