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Proteins

Proteins. Recognize the monomers of proteins Describe the structure and function of proteins. Explain why so many different types of proteins are possible. Discuss the relationship between an enzyme, substrate, and active site. Learning Targets.

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Proteins

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  1. Proteins

  2. Recognize the monomers of proteins Describe the structure and function of proteins. Explain why so many different types of proteins are possible. Discuss the relationship between an enzyme, substrate, and active site. Learning Targets

  3. Proteins are macromolecules that contain nitrogen as well as carbon, hydrogen, and oxygen. Proteins are polymers of molecules called amino acids. Proteins: MONOMERS!

  4. Proteins make up 15% of your biomass! Involved in nearly every function of your body. Cells contain about 10,000 different proteins. Proteins:

  5. There are 20 different kinds of amino acids, all with the same basic structure! Proteins:

  6. Amino acids are compounds with: An amino group (-NH2) A carboxyl group (-COOH) Proteins: Hydrogen atom Carboxyl group Amino group R group (side chain)

  7. Amino acids are named for their different “R”- groups. R-Group: side chain that makes each amino acid (monomer) unique.

  8. How are proteins made? • The amino group (-NH2) reacts with the carboxyl group (-COOH). • This occurs by dehydration synthesis! • Peptide Bond: a bond formed between amino acids. • Dipeptide: TWO amino acids bonded together. • Polypeptide: more than two amino acids bonded together..

  9. + + + 2 H20 Peptide Bonds

  10. Protein Structure • A PROTEIN is composed of hundreds to thousands of amino acids. • The sequence of the amino acids determines the protein’s folding pattern and therefore unique structure. • The unique 3-D structure of a protein determines its FUNCTION.

  11. Two sample polypeptide chains: Polypeptide A Ala- Ser-Tyr- Ala-Glu- Ser- Glu– Glu –Phe –Try- Ser Polypeptide B Ala- Ser-Tyr- Ala- Glu- Ser- Glu- Phe- Try- Ser- Ala

  12. Fibrous Proteins Usually structural proteins.

  13. Globular Proteins Usually enzymes.

  14. Structural Proteins Enzymes

  15. Remember!!! Sequence of AA determines how it folds determines its shape determines proteins function

  16. Example: Here is a sample amino acid sequence from a typical protein in steak (or chicken, fish, beans, nuts, etc.)… Val – Glu – Leu – His – Ser – Pro

  17. Protein Function: Form body/cell structures

  18. Protein Function: 2. Control chemical reactions in cells as ENZYMES Enzymes are very efficient catalysts for biochemical reactions CATALYSTS: molecules that speed up reaction rates

  19. ENZYMES are globular proteins that control chemical reactions in living things. In any living thing, the chance that two molecules (A and B) will meet and react at the right place, the right time, and in the right positions is completely RANDOM.

  20. Substrates A active sites B Enzyme AB + H2O A + B + Energy

  21. How do enzymes work? Enzymes attract and hold the substrates. The substrate fits perfectly into the active site. Enzymes decrease the amount of activation energy. The enzyme does its job (usually combines or changes the substrate) and releases it. The enzyme can be used over and over again. Everybiological process requires an enzyme.

  22. Lock and Key Hypothesis: Proteins bind to each other by matching up knobs and depressions on the proteins surfaces, in much the same way that a key fits into a lock.

  23. Enzymes are affected by… • Note: Enzymes names tend to end with an -ase such as catalase, lipase, sucrase, peptidase, etc Temperature pH Inhibitors (block an enzyme)

  24. Lets Review!

  25. Lets Review: • Amino Acid: building blocks of all proteins. • They all have the same general structure. • Amino Group (-NH2) • Carboxyl Group (-COOH) • R Group • Hydrogen atom

  26. Different Sizes of Proteins Amino acids are held together by peptide bonds.

  27. How can proteins differ? • Number of amino acids. • Type of amino acids. • Sequence of amino acids. • Shape of the protein. • Different shapes have different functions. • The unique way a protein folds (its 3-D structure) determines its function. • Sequence  Folding  Shape  Function

  28. Vocabulary Protein Amino Acid Dipeptide Enzyme Peptide Bond Polypeptide Catalyst Substrate Active Site

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