Chapter 5 protein.ppt

Chapter 5 The Structure and Function of Large Biological Molecules PowerPoint® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Copyright © 2008 Pearson Education, Inc., publishing as P...

Chapter 5 The Structure and Function of Large Biological Molecules PowerPoint® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 5.4: Proteins have many structures, resulting in a wide range of functions • Proteins account for more than 50% of the dry mass of most cells and 15% of the total weight. • The Basic Structure of protein is a Chain of Amino Acids. • Proteins are polymers of Amino Acids Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Table 5-1 Questions • Q1. List three functions of proteins? • Q2. What is the basic Structure of a Protein? Amino Acids • An organic molecule that, when linked together with other amino acids, forms a protein Amino Acid Structure • Generally, Amino Acids have the following: • A carbon • A hydrogen atom (H) • A Carboxyl group (-COOH) • An Amino group (-NH2) • A "variable" group or "R" group Fig. 5-UN1 carbon Amino group Carboxyl group QUESTIONS • Q3. What are the components that make up an Amino Acid? The R- Group • The "R" group varies among amino acids and determines the differences between these protein monomers. Fig. 5-17 Nonpolar Glycine (Gly or G) Valine (Val or V) Alanine (Ala or A) Methionine (Met or M) Leucine (Leu or L) Trypotphan (Trp or W) Phenylalanine (Phe or F) Isoleucine (Ile or ) Proline (Pro or P) Polar Serine (Ser or S) Threonine (Thr or T) Cysteine Tyrosine (Cys or C) (Tyr or Y) Asparagine Glutamine (Asn or N) (Gln or Q) Electrically charged Acidic Aspartic acid Glutamic acid (Glu or E) (Asp or D) Basic Lysine (Lys or K) Arginine (Arg or R) Histidine (His or H) QUESTIONS • Q4. What are the types of Amino Acids? Peptide Polypeptide, and Proteins • A peptide contains two or more amino acids • polypeptide is an organic compound of amino acids that contains ten or more amino acids. • If there are more than fifty amino acids, this is now considered a protein. • A protein consists of one or more polypeptides Cop © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-18 Peptide bond (a) Side chains Peptide bond Backbone (b) Amino end (N-terminus) Carboxyl end (C-terminus) QUESTIONS • Q5 Define the following: • Peptide: • Polypeptide: • Protein: Four Levels of Protein Structure • The primary structure of a protein is its unique sequence of amino acids • Secondary structure, found in most proteins, consists of coils and folds in the polypeptide chain • Tertiary structure is determined by interactions among various side chains (R groups) • Quaternary structure results when a protein consists of multiple polypeptide chains Animation: Protein Structure Introduction Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Protein Structures • Primary structure, the Linear Sequence of amino acids in a protein, is like the order of letters in a long word. • Primary structure is determined by inherited genetic information. Animation: Primary Protein Structure Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-21b 1 5 H3N Amino end + 10 Amino acid subunits 15 20 25 75 80 90 85 95 105 100 110 115 120 125 Carboxyl end QUESTIONS • Q6: Define the primary structure of Protein? • The coils and folds of secondary structure result from hydrogen bonds between repeating constituents of the polypeptide backbone • Typical secondary structures are a coil called an  helix and a folded structure called a  pleated sheet Animation: Secondary Protein Structure Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-21c Secondary Structure Beta pleated sheet Examples of amino acid subunits Alpha helix QUESTIONS • Q7: Explain the Secondary Structure of Protein? • Tertiary structure is a protein’s Geometric shape determined by interactions between R groups, rather than interactions between backbone constituents • These interactions between R groups include hydrogen bonds, ionic bonds, hydrophobic interactions, di sulfide bridges, and van der Waals interactions Animation: Tertiary Protein Structure Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Tertiary structure Fig. 5-21f Hydrophobic interactions and van der Waals interactions Polypeptide backbone Hydrogen bond Disulfide bridge Ionic bond QUESTIONS Q8. What is the Tertiary Structure of Protein? • Quaternary structure results when two or more polypeptide chains form one macromolecule • Collagen is a fibrous protein consisting of three polypeptides coiled like a rope • Hemoglobin is a globular protein consisting of four polypeptides. Animation: Quaternary Protein Structure Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Hemoglobulin Collagen QUESTIONS • Q9. Outline the Quaternary Structure of Protein? What Determines Protein Structure? • In addition to primary structure, physical and chemical conditions can affect structure • Alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein to break. • This loss of a protein’s native structure is called denaturation • A denatured protein is biologically inactive Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-23 Denaturation Normal protein Renaturation Denatured protein QUESTIONS • Q10: What is Denaturation? • Enzymes are a type of protein that acts as a catalyst to speed up chemical reactions • Enzymes are not consumable • Most enzymes names end up with “ase” Animation: Enzymes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-16 Substrate (sucrose) Glucose OH Fructose HO Enzyme (sucrase) H2O