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Protein Structure: Levels, Functions, and Building Blocks

Explore the complex levels of protein structure, from primary to quaternary, understanding their functions in muscles, hormones, transportation, and enzymes. Learn about amino acids, peptide bonds, and the significance of the peptide bond. Discover the critical role of primary sequences, the folding patterns of secondary structures like alpha helices and beta sheets, and the 3D shapes of tertiary and quaternary protein structures. Understand denaturation and how environmental changes affect protein function. Additionally, delve into the world of nucleic acids, comparing DNA and RNA structures and compositions. Enhance your knowledge of the central dogma of biology through the processes of transcription and translation.

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Protein Structure: Levels, Functions, and Building Blocks

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  1. Protein- Secondary, Tertiary, and Quaternary Structure

  2. Levels of Protein Structure

  3. Proteins Functions of Proteins: • Structural: Muscles, Antibodies • Hormones: insulin, thyroxin • Cell Transport Proteins • Enzymes are Proteins Central Dogma of Biology DNA mRNAProtein TranscriptionTranslation

  4. Protein Building Blocks Amino acid structure: NH3 – C - COOH

  5. R Groups • Nonpolar • Polar • Charged • + Charged • - Charged

  6. Nonpolar R Groups

  7. Nonpolar R Groups

  8. Polar, but NOT Charged amino acids

  9. Polar, but NOT Charged amino acids

  10. Polar, Charged (Acidic) amino acids

  11. Basic amino acids

  12. Structure of R-group determines the chemical properties of the amino acid • The polar uncharged amino acids are hydrophilic and can form hydrogen bonds • The nonpolar amino acids are hydrophobic and are usually found in the center of the protein; they are also found in proteins which associated with cell membrane • The electrically charged amino acids have electrical properties that can change depending on the pH • Cysteine can form disulfide bond • Proline has a unique structure and causes kinks in the protein chain • When 2 amino acids are joined, the bond formed is called peptide bond

  13. Building Proteins: The Peptide Bond

  14. Peptide Bond OH CN You must be able to draw this bond, recognize this bond, and the significance of this bond.

  15. Primary Structure of Proteins • The sequence of amino acids in the polypeptide chain • The sequence of R groups determine the properties of the protein • A change of a single amino acid can alter the function of the protein • Sickle Cell Anemia- caused by a change of one amino acid from glutamine to valine

  16. Secondary Structure of Protein • Folding and coiling due to hydrogen bond formation between carboxyl and amino group of non-adjacent amino acid • These bonds occur between the BACKBONE of the strand of amino acids • R groups are NOT involved • Folding is due to the disulfide bond • Two common examples: alpha helix and beta pleated sheet

  17. Secondary Structure of Protein

  18. Folding due to Disulfide bond

  19. Tertiary Structure of Protein • 3-D structure resulting from the folding of 2o structural elements • Stabilized by bonds formed between amino acid R groups • Form many shapes (globular compact proteins and fibrous elongated proteins)

  20. Tertiary Structure of Proteins

  21. Quaternary Structure of Protein • Multiple polypeptide chains bonded together • 3-D structure due to interactions between polypeptide chains • R-group interactions, H bonds, ionic interactions • Assembled after synthesis • Only proteins with more than one subunit can have a quaternary structure

  22. Quaternary Structure of Protein

  23. Denaturation • Environment change (increased heat, changes in pH) proteins can unfold or “denature” • Loss of dimensional shape loss of protein function • Sometimes able to refold back into it’s original conformation

  24. Nucleic Acids DNA RNA

  25. Nucleic Acids • 3 components to a nucleotide: a pentose sugar, a phosphate group, and a nucleotide base

  26. Nucleic Acids (2 Common forms): • RNA (ribonucleic acid) • DNA (deoxyribonucleic acid)

  27. DNA & RNA differ by the presence on an –OH group (RNA) or an H-group (DNA) on the 2’ carbon of the pentose sugar

  28. DNA contains C, T, A, G RNA contains C, U,A, G

  29. DNA: double stranded RNA: single stranded

  30. When a DNA or RNA polymer is created, the bond is formed between 3’ –OH group and 5’ phosphate group  phosphodiester bond

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