Chemical Bonding 1. Covalent Bond - strong bond, formed by sharing of 2 or more electrons  Example: C 6 H 12 O 6 & any organic molecules 2. Ionic Bond – formed by the transfer of 1 or more electrons  Example: NaCl & MgCl 2  Cation – positive  Anion - negative

… 3. Hydrogen Bonding – weak bond formed by hydrogen w/i a molecule being attracted by oxygen & nitrogen w/i a molecule  Important in DNA and proteins

Macromolecules of Life Abundance in a cell:  Proteins (55%)  Nucleic acids (24%)  Lipids (9%)  Carbohydrates (5%)  Lipopolysacharides (3%)  Other (4%) = inorganics

Question: How Are Macromolecules Formed?

Answer: Dehydration Synthesis “condensation reaction”  Also called “condensation reaction” polymers monomers“removing water”  Forms polymers by combining monomers by “removing water”. HOH HH H2OH2O

Question: How are Macromolecules separated or digested?

Answer: Hydrolysis monomers“adding water”  Separates monomers by “adding water” HO HH H H2OH2O

Proteins  Building block is amino acids (22-23)  2 main functions:  Structural (cell wall)  Functional (enzymes)  Primary Structure – list of amino acid sequence  Secondary Structure – twists & folds in primary sequence  Tertiary Structure – sulfur cross-bridging  Gives rigidity  Quaternary Structure – 2 or more proteins come together

…  Central Dogma DNA → RNA → protein ↑ ↑ transcription translation Genotype Phenotype

Nucleic Acids  Building blocks are nucleotides  Sugar, phosphate, & nitrogen base  Nitogen bases: adenine, cytosine, guanine, thymine, uracil (a=t) & (c=g) & (a=u)  Functions – genetic storage: chromosome  RNA has multiple functions:  mRNA – RNA copy of DNA  rRNA – part of ribosome, helps to make proteins  tRNA – carries amino acids to ribosome

Lipids  Building blocks vary, but include fatty acids and other hydrophobic molecules  Important in cell membrane structure & fluidity  Inhibits diffusion of cell  Serves as high energy storage compound

Carbohydrates  Building blocks are simple sugars (glucose, ribose)  Cell wall constituents (peptidoglycan)  Cell recognition factors in membranes  lipopolysaccharides  Serves as high energy storage compounds (glycogen)  Serve as bacterial ‘food’ (chemoheterotrophs)

2 monosaccharides make a disaccharide

Monomer to disaccharide to polysaccharide