1. Molecules of Life II CHAPTER 3 Proteins Amino Acid Monomers Polypeptide (protein) Polymers Levels of Protein Structure Importance of Structure to Function Nucleic Acids Nucleotides Polymers DNA vs.. RNA

2. Proteins A protein is a polymer constructed from amino acid monomers. Proteins perform most of the tasks the body needs to function: Structural Support Storage Movement Transport Body or Cellular Defense Docking and Reception Catalysis (Enzymes) Chemical messaging (hormones) Sensing Regulation and Control

3. Figure 3.19 Examples of Some Types of Proteins and Their Functions

4. The Monomers: Amino Acids All proteins are constructed from a common set of 20 kinds of monomers known as amino acids or peptides Each amino acid consists of: 2. An amino (NH 2 ) group, which is basic and polar 3. A carboxyl ( ) group, which is acidic and polar 4. A side group that can be either hydrophobic or hydrophylic 1. A central carbon atom bonded to four covalent partners

5. Figure 3.1 Example of An Amino Acid Which Allegedly Makes One Sleepy

6. Proteins as Polymers Cells link amino acids together by dehydration reactions, forming peptide bonds between them

7. Your body has tens of thousands of different kinds of protein. –The kind and arrangement of amino acids makes each one different. Protein Polymers (Polypeptides) are Highly Variable –Once an amino acid chain is built inside a cell, the chain folds up into a unique shape –Because structure gives rise to function, two proteins with even slightly different structure fold differently and behave differently –Any chemical or type of stress that changes the folded structure of a protein ruins its functionality Protein Structure Introduction

8. Molecules of Life II CHAPTER 3 Proteins Amino Acid Monomers Polypeptide (protein) Polymers Levels of Protein Structure Importance of Structure to Function Nucleic Acids Nucleotides Polymers DNA vs.. RNA

9. 1.Primary (1 o ) structure The specific kinds of amino acids and their sequence in a polypeptide (protein chain) A slight change in the primary structure of a protein affects its ability to function. Four Levels or Degrees of Protein Folding Primary Protein Structure

10. Four Levels or Degrees of Protein Folding The polypeptide chain folds into an alpha helix, sustained by H- bonds. (b) Secondary Structure The polypeptide chain folds into a pleated sheet, sustained by H- bonds 2. Secondary (2 o ) structure

11. Four Levels or Degrees of Protein Folding 3. Tertiary (3 o ) structure The alpha helices and pleated sheets then fold among each other New level of structure is supported by hydrogen, ionic, disulfide, and non- polar bonds Tertiary Structure

12. Four Levels or Degrees of Protein Folding 3. Quaternary (4 o ) structure Several polypeptide chains join together to form a protein complex with subunits Unfavorable temperature and pH changes can cause a protein to unravel and lose its shape (denature) and thereby lose functionality (d) Quaternary structure

13. Molecular Reconstruction of a Quaternary Structured Protein

14. The Strength of Spider and Silkworm Protein Especially strong because of multiple pleated sheet structures These proteins are five times as strong as steel, twice as elastic as nylon, waterproof, and stretchable Hydrogen bonds

15. Molecules of Life II CHAPTER 3 Proteins Amino Acid Monomers Polypeptide (protein) Polymers Levels of Protein Structure Importance of Structure to Function Nucleic Acids Nucleotides Polymers DNA vs. RNA

16. Nucleic Acids Nucleic acids are information storage molecules. –They provide the directions for building proteins. Nucleic acids are build of monomers called nucleotides –Ribonucleotides are used in making the polymer called ribonucleic acid (RNA) –Deoxyribonucleotides are used in making the polymer called deoxyribonucleic acids (DNA)

17. Nucleotides are Composed of a Phosphate, Sugar, and Nitrogenous Base

18. Nitrogenous Bases Contain Either One or Two Rings

19. Nucleotide monomers are linked into long chains. –These chains are called polynucleotides, or DNA strands. –A sugar-phosphate backbone joins them together. DNA and RNA Structure

20. Nucleic Acids Are Polymers of Nucleotides RNA is a simple chain of ribonucleotides

21. DNA is a Double Stranded Molecule Held Together By Hydrogen Bonds DNA Molecule as a Ladder: Two Rails Held Together By Rungs The DNA Molecule is twisted into a spiral in 3-dimensional space

22. Evolution Connection: DNA and Proteins as Evolutionary Tape Measures Evolutionary relationships between organisms can be assessed. –Molecular genealogy extends to relationships between species. Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings

23. Figure 3.30 Genetic and Evolutionary Relatedness Can Be Determined From DNA and Protein Similarities

24. Molecules of Life II CHAPTER 3 Proteins Amino Acid Monomers Polypeptide (protein) Polymers Levels of Protein Structure Importance of Structure to Function Nucleic Acids Nucleotides Polymers DNA vs.. RNA