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Proteins & Nucleic Acids

Proteins & Nucleic Acids.

honorato-pearson
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Proteins & Nucleic Acids

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  1. Proteins & Nucleic Acids Images taken without permission from http://upload.wikimedia.org/wikipedia/de/4/4d/Protein_GFP_1EMA.png, http://cmgm.stanford.edu/biochem201/Slides/Protein%20Structure/Levels%20of%20Protein%20Structure.JPG, http://www.lakemichigancollege.edu/dept/Arts-Sciences/bio/pics/DNA.gif

  2. Proteins: A General Overview • Biological roles: enzymes, structural components, hormones, immune function, storage, transport, muscle contraction • Monomer = amino acid • Polymer = polypeptide chain (protein)

  3. R group Carboxyl group Amino group Central carbon hydrogen Monomer = amino acid • There are 4 components attached to a central carbon • There are 20 different amino acids • the R group for each amino acid is different determines its properties

  4. Classes/Categories of Amino Acids • The R group determines the class/category of an amino acid • General categories: • Nonpolar • Polar • Positively Charged • Negatively Charged

  5. Peptide bond Peptide Bonds • Formation of a protein occurs when amino acids covalently bond through the formation of a peptide bond. • What kind of reaction forms a peptide bond? • Dehydration reaction

  6. All proteins have primary, secondary and tertiary structure Four Levels of Protein Structure • Primary • Secondary • Tertiary • Quaternary • Only proteins with multiple chains will have this level of structure

  7. Primary Sequence of Hemoglobin Chain A: VLSPADKTNVKAAWGKVGAH......etc N terminus C terminus Primary Structure (1°) • The sequence of amino acids • All other structures are based on this level of structure

  8. Secondary Structure (2°) • Local helical coiling (alpha helix) or pleated sheet (beta sheet) formations in the chain • Patterned formations based on hydrogen bonds between non-adjacent amino acids

  9. Tertiary Structure (3°) • The way the polypeptide chain is folded three dimensionally. • Is brought about through the following interactions: • Disulfide bridges • Ionic interactions • Hydrophobic interactions • Hydrogen bonds

  10. Quaternary Structure (4°) • Interaction between two or more polypeptide chains.

  11. Important Protein Concept • Changes in protein structure can lead to disease • Ex. Sickle cell anemia = disease caused by a single amino acid substitution in the b chain of hemoglobin Image taken without permission from http://www.sciencecollege.co.uk/SC/natural_selection/sickle_cell.jpg

  12. Protein Folding Denaturation = unfolding of protein • Proteins are folded into the appropriate formation during or after protein synthesis • Certain conditions such as temperature, pH, and salt concentrations can alter the shape of a protein • Chaperonins assist to fold proteins correctly in the cell • Think “chaperones”

  13. Nucleic Acids • Biological roles = Store/carry genetic information, form part of ribosomes, energy carriers • Monomer = Nucleotide (A, T, C, G) • Polymer = Nucleic Acid • DNA • RNA

  14. Nucleotide Components • Consist of 3 parts: • Phosphate group • 5 carbon (pentose) sugar • Nitrogenous base • A, T, C, G, U (RNA only)

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