Biological Molecules


  1. Importance of Carbon

  1. Intro to Carbon

  • Carbon → 4 single valence electrons → tetravalent

  • Organic Compounds = contain carbon bonded to C or H 

  • Carbon chains - skeletons of organic molecules

  • Structure is Key to Molecular Function

  • Length, Double Bond Positions, Branching, Presence of Rings → ways carbon can bond with other elements

  • Carbon and Hydrogen have very similar electronegativity so it's easier for them to bond

  • Functional Groups = R, R could be anything it’s basically a placeholder Molene

  • Functional Group →

  1. Hydrocarbons

  • Hydrocarbons = carbon and hydrogen

  • Example of hydrocarbon → methane = CH4

  • Nonpolar and uncharged = Hydrophobic = insoluble in H2O

  • Different functional groups change molecular functions

  • Functional groups designated R

  1. Functional Groups

  1. Hydroxyl Group (R-OH)

  • Alcohol (ends in -ol)

  • Polar → yes

  • Hydrophilic → yes

  • Acidity → neutral 

  1. Carbonyl Group (CHO)

  • Aldehyde/Ketone → depends on location of C-O

  • Polar → yes

  • Hydrophilic → yes, but less than -OH

  • Acidity → neutral in solution normally

  1. Carboxyl Group (R-COOH

  • Carboxylic Acids (H+ easily released)

  • Polar → yes

  • Hydrophilic → yes

  • Acid → yes

  • Amino Acids make up proteins

  1. Amino Group (R-NH2)

  • Amines (H+ easily accepted)

  • Polar → yes

  • Hydrophilic → yes

  • Acid → No it is a BASE

  1. Sulfhydryl Group (R-SH)

  • Thiols

  • Polar → yes

  • Hydrophilic → yes

  • Acid → very slightly acidic

  • Holds some protein structure: Two -SH form stable “cross-link” 

  • Less polar than hydroxyl

  1. Phosphate Group (R-PO4H2)

  • Organic Phosphate

  • Polar → yes

  • Hydrophilic → yes

  • Acid → yes

  • Often contribute negative charge

  • Phospholipids and nuclein acids (DNA, RNA)

  1. Methyl Group (R-CH3)

  • Methyl Hydrocarbon

  • Polar → NO

  • Hydrophilic → No it is HYDROPHOBIC

  • Acid → Neither Acid nor Base → it is neutral

  • Control of Gene Expression

  • Shape and Function of Sex and Hormones

2. Biological Macromolecules

  1. Macromolecules

  • Monomers = building blocks of macromolecules

  • Monomers join together to form polymers

  • 3 out of 4 biological molecules are polymers: 1. Carbohydrates, 2. Proteins, 3. Nucleic acids

  • Lipids are biological molecules but NEVER polymers

  • Dehydration Synthesis → remove water and joins; enzymes used are Dehydrogenases

  • Hydrolysis → adds a water molecule and breaks; enzymes used are Hydrolases

  1. Carbohydrates

  • CH2O (most of CHON)

  • Monomer → sugars (monosaccharides), glucose (C6H12O6)

  • Polymer → polysaccharides, fuel and building material

  • Glucose → Linear and Ring form (more typical)

  • Ring formed in 2 ways → a or B glucose

  • Covalent bonds between Monosaccharides = Glucosidic Linkage

  • If just 2 monomers = Disaccharide; ex. Sucrose = glucose + fructose

  • -ose = sugar, -ase = enzyme

  • If more than 2 monomers in a chain, sugar polymers = polysaccharides

  • Depending on type of monomers and types of glycosidic linkages

  • Functions as energy OR structural support

  1. Lipids

  • Lipids are NOT POLYMERS

  • Hydrophobic: mostly hydrocarbons

  • 3 families: fats, phospholipids, steroids

  • Fats → function = energy storage

  • Consists of glycerol = 3 carbon alc with 3 -OH

  • 1,2, or 3 fatty acids

  • Fatty Acids + Glycerol 

  • Dehydration Synthesis → covalent bond = ester linkage

  • Presence of double bonds determines if fat is a saturated fatty acid or unsaturated fatty acid 

  • Phospholipid (negative charge) = cell membranes

  • Amphipathic = glycerol + 2 fatty acids (hydrophobic) phosphate group (hydrophilic)

  • Steroids = 3 rings of 6 C & 1 ring of 5 C

  • Side chains or functional groups vary

  • Cholesterols in animals → communications, cell membrane structure

  • Cortisol = stress hormone

  1. Proteins

  • Peptide Bonds between amino acids (monomers) dehydration synthesis reaction

  • Polypeptide is a sequence of amino acids: each AA is bound to the next with a peptide bond 

  • BUT!!!! It MUST BE FOLDED into correct 3D shape to become a protein

  • Primary Structure: sequence of amino acids joined by peptide ponds in polypeptide chain, DETERMINED BY DNA

  • Secondary Structure: within a single polypeptide Hydrogen bonds stick AAs together: amino group, carboxyl group

  • R groups do NOT participate in secondary structure 

  • a Helix = coil

  • B = pleated sheet

  • Tertiary Structure: within a single polypeptide R-groups interact folds into a particular 3-D shape

  • Quaternary Structure: multiple polypeptide chains form one macromolecule (no more folding)

  • Denaturation = loss of a protein’s 3rd or 4th structure 

  • A denatured protein is BIOLOGICALLY INACTIVE

  • Ph, salt concentration, and temperature

  1. Nucleic Acids

  • Monomers are nucleotides

  • 2 classes: DNA (deoxyribonucleic acid), RNA (ribonucleic acid)

  • Transmit hereditary info & determine protein production