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Nucleotides, Hydrolysis, and Proteins

Nucleotides, Hydrolysis, and Proteins. nucleotide. Hydrolysis This is a type of reaction in which a macromolecule is broken down into smaller molecules. It is the reverse of condensation. Proteins. Composed of Amino Acids

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Nucleotides, Hydrolysis, and Proteins

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  1. Nucleotides, Hydrolysis, and Proteins

  2. nucleotide

  3. Hydrolysis • This is a type of reaction in which a macromolecule is broken down into smaller molecules. • It is the reverse of condensation.

  4. Proteins • Composed of Amino Acids • Consist of a Carboxyl group, an amine group, and a variable (“R” group) • The R group is the defining group for the 20 different types of amino acids • Polypeptide chains are put together using Dehydration Synthesis.

  5. Proteins • When two amino acids are added together, they are always joined in the same way. • The carboxyl group of one amino acid is connected to the amine group of the other amino acid. • This bond is called a peptide bond

  6. Proteins • Importance of proteins • enzymes (chemical reactions) • hormones • storage (egg whites of birds, reptiles; seeds) • transport (hemoglobin) • contractile (muscle)

  7. Proteins • protective (antibodies) • membrane proteins (receptors, membrane transport, antigens) • structural • toxins (botulism, diphtheria)

  8. Proteins • Each protein has a unique shape. • This shape (form) determines how the protein functions. • 4 levels of protein structure • Primary • Secondary • Tertiary • Quaternary (Not all proteins)

  9. Proteins • Primary Structure – refers to the order of the amino acids in the polypeptide chain • A change in 1 amino acid can have drastic consequences. Ex. Sickle Cell Anemia • Secondary Structure – results from hydrogen bonding within the polypeptide molecule.

  10. Proteins • 2 types of secondary structure: • Alpha helix • Beta pleated sheet • Proteins exhibiting these structures are called fibrous proteins • Wool, claws, beaks, collagen, ligaments

  11. Proteins • Tertiary Structure – 3-D shape of a protein • Determines the specificity • Factors that affect the tertiary structure: • H-Bonding between R groups • Ionic bonding between R groups • Hydrophobic interactions • Van der Waals interactions • Disulfide bonds between cysteine

  12. Proteins • Quaternary Structure • Proteins that consist of more than one polypeptide chain • Ex. Hemoglobin – Alpha + Beta

  13. Form vs. Function • It is not understood how proteins spontaneously fold into unique shapes. • Proteins interact with each other to control cellular processes. • The shape of a protein determines its function.

  14. Enzymes • Enzymes are globular proteins • Exhibit tertiary structure • Lower the activation energy of a reaction • Enzymes are substrate specific • An enzyme will on work on a specific substrate. • Enzymes are not used and remain unchanged during a chemical rxn.

  15. Induced-Fit Model • As a substrate enters the active site, it causes a slight change in the shape of the enzyme. This change in the shape of the enzyme causes the substrate to fit better.

  16. Enzymes • Named based on their substrate. • Name ends in “-ase” • Ex. Lactase, Sucrase, Ligase, Helicase • Catalyze reactions in both directions • Ex. Sucrase helps to break down and form Sucrose • Often require cofactors (inorganic) or coenzymes (vitamins)

  17. Enzymes • Enzymes are not only substrate specific but are temperature and pH specific. • When the temp. or pH is too high/low, an enzyme will begin to denature. • Ex. Gastric enzymes are effective at a low pH (~2)

  18. Inhibition of Enzymes • Competitive Inhibition • Occurs when a compound resembles the normal substrate for an enzyme

  19. Inhibition of Enzymes • These competitive inhibitors reduce the productivity of the enzyme. • Prevents the substrate form combining with the enzyme. • Can be reversible or irreversible.

  20. Inhibition of Enzymes • Non-competitive inhibition • Enzymes contains more than 1 active site • Substrates do not resemble each other • When one substrate binds to one active site, the other substrate cannot bind to the enzyme • Concentration of the substrates has a large effect on which one binds to the enzyme

  21. Inhibition of Enzymes • Allosteric inhibition • Involves 2 active sites • 1 substrate • 1 inhibitor • Enzyme ocscillates between two conformations • When the inhibitor binds, the enzyme becomes inactive.

  22. Allosteric Inhibition • Example – phosphofructokinase (PFK) • Found in glycolysis • Inhibited by ATP, which is a product of glycolysis • Example of Feedback inhibition • Pathway is switched off by its end-product

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