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Chemical Foundations

Chemical Foundations. Presented by Shana Shanto February 9, 2004. Types of Molecular Interactions. 1) Covalent Two atoms share one or more pairs of electrons Strong May be Polar or Non-polar 2) Non-covalent Weak 4 Major Types 1. Ionic Interactions 2. Hydrogen Bonds

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Chemical Foundations

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  1. Chemical Foundations Presented by Shana Shanto February 9, 2004

  2. Types of Molecular Interactions 1) Covalent • Two atoms share one or more pairs of electrons • Strong • May be Polar or Non-polar 2) Non-covalent • Weak • 4 Major Types 1. Ionic Interactions 2. Hydrogen Bonds 3. Van der waals Interactions 4. Hydrophobic Effect

  3. Ionic Interactions Attraction Between a Cation and an Anion Hydrogen Bonds Attraction between a covalently bonded hydrogen with a partial positive charge and another atom (usually C or N) with a partial negative charge

  4. Van der Waals Interactions Weak attractive force between two atoms in close proximity as a result of transient dipoles in their electron clouds Hydrophobic Interactions Tendency of non-polar hydrophobic molecules or portions of molecules to aggregate in water

  5. Molecular Complementarity • Involves shape, charge, and other factors • Allows molecules to interact tightly • Enzyme-substrate interactions

  6. Biological Macromolecules • Polymers of identical or nearly identical monomers • The 3 most abundant in biological systems are: 1) Proteins 2) Nucleic Acids 3) Polysaccharides

  7. Proteins • Composed of amino acid monomers linked by peptide bonds • Peptide bonds are formed by a dehydration reaction • 19 Amino Acids and 1 Imino Acid (Proline) compose all proteins • Only L amino acids are found in proteins • All amino acids have the same basic structure

  8. Nucleic Acids • Composed of nucleotide monomers • 2 Types: 1) DNA 2) RNA • 2 Types of Bases • Purines have 2 fused rings (Adenine & Guanine) • Pyrimidines have a single ring (Uracil, Thymine, & Cytosine)

  9. Nucleic Acids Continued • Nucleotides are joined by phosphodiester bonds

  10. Polysaccharides • Composed of monosaccharide monomers • Monosaccharides are composed of Carbon and water in a 1:1 ratio • Hexoses and Pentoses are most common • Glucose is an important monosaccharide with 3 forms

  11. Polysaccharides Continued • Monosaccharides join through glycosidic linkages to form polysaccharides

  12. Fatty Acids • Composed of a hydrocarbon chain attached to a carboxyl group • No monomeric subunits • Saturated FA have no carbon-carbon double bonds • Unsaturated FA have at least one double bond • Double bonds create kinks in the chain

  13. Phospholipids • Consist of 2 non-polar long chain fatty acyl chains linked to a polar group including a phosphate • Amphipathic • Building blocks of biological membranes • Phospholipid Bilayer due to hydrophobic effect

  14. Summary/Conclusions • Proteins, nucleic acids, polysaccharides, and lipids play important roles in biological systems • Covalent bonds provide strong linkages within and between these molecules • Non-covalent interactions such as hydrogen bonds are weaker, but are still important because they allow flexibility and are collectively strong • Molecular complementarity allows these molecules to interact with each other and with other molecules and to perform their specific functions, especially in the case of enzymes.

  15. ThankYou Questions???

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