1. Chapter 05

2. Building Proteins DNA’s instructions are translated into thousands of proteins that do a cell’s work Protein molecules communicate and coordinate activities to perform life’s functions

3. Roles of Proteins Enzymes: Catalysts Have specific shapes that recognize specific molecules (active sites) Remain unchanged in reactions – can be used over again

4. Roles of Proteins Transporters Located in cell membrane Function as tunnels and pumps – allow material to pass in and out of cell

5. Transport Proteins Facilitated Diffusion (top) and Active Transport (bottom)

6. Roles of Proteins Movers Protein chains can change shape in response to energy (ATP)

7. Roles of Proteins Supporters Long chains of folded or coiled proteins Form sheets or tubes Help support and shape the cell

8. Types of Support Fibers Found in Cells

9. Roles of Proteins Regulators Enzymes that respond to feedback Notice when enough final product accumulates and stop assembly cycle

10. Roles of Proteins Defenders Antibodies – recognize and bind to foreign substances so that scavenger cells can destroy them

11. Structure of an Antibody Molecule

12. Roles of Proteins Communicators Example – hormones Act as cell’s chemical messengers

13. How Peptide Hormones Work

14. Proteins at Work Example: Actin and Myosin Make muscles work Small molecular changes produce large effects

15. Proteins at Work Actin and myosin line up and use ATP to shorten and lengthen themselves

16. Proteins at Work Muscle contraction is collective action of millions of actin-myosin combinations

17. Actin Microfilaments

18. Proteins Chains of amino acids linked by strong covalent bonds 20 different amino acids Shape and function of protein are determined by amino acid sequence

19. Proteins

20. Amino Acids All twenty contain carbon, hydrogen, oxygen, and nitrogen Two contain sulfur Ten have electrically charged side groups that are attracted to water – cluster on surface of protein Ten have no electrical charge – cluster on inside of protein

21. Some Common Amino Acids

22. Protein Folding Weak bonds between amino acids in a chain allow protein to fold Weak bonds are easily broken and reformed – provide flexibility and mobility

23. Protein Folding Water environment: fat- liking amino acids fold inside protein molecule, water- liking amino acid face out Fat environment: water-liking amino acids inside, fat- liking amino acids face out

24. Amino Acid Sequence Determines Protein Shape

25. Translation DNA is a chain of nucleotides Nucleotide triplets are translated into one of twenty different amino acids Average gene = 1200 nucleotides – translates into protein 400 amino acids long

26. Nucleotide Triplets are Translated into Amino Acids

27. How To Read the Genetic Code

28. Overview of Protein Synthesis Copy nucleotide sequence of a gene into messenger RNA (transcription) Attach amino acids to transfer RNA Bring transfer RNA with amino acids and messenger RNA to ribosome (protein synthesis factory) Ribosome links amino acids to make a protein

29. Overview of Protein Synthesis

30. Translation Energizing Amino Acids and Linking Them to Transfer RNA Key Players: Amino Acid Transfer RNA (adaptor) ATP Activating Enzyme

31. Transfer RNA

32. Translation Energizing Amino Acids and Linking Them to Transfer RNA 1. ATP and an amino acid dock on the activating enzyme and bond with each other

33. Translation Energizing Amino Acids and Linking Them to Transfer RNA 2. The amino acid is energized

34. Translation Energizing Amino Acids and Linking Them to Transfer RNA 3. Transfer RNA (adaptor) docks at a nearby site on the enzyme

35. Translation Energizing Amino Acids and Linking Them to Transfer RNA 4. The transfer RNA and the amino acid are joined. The spent ATP is released.

36. Translation Energizing Amino Acids and Linking Them to Transfer RNA 5. The transfer RNA is released with the amino acid attached

37. Translation Assembling the Protein Chain Key Players: Ribosomes- Organelles where proteins are manufactured Consists of two subunits Some attached to rough endoplasmic reticulum, others bound to cytoskeletal fibers

38. Translation Assembling the Protein Chain 1. Messenger RNA attaches to the smaller subunit of the ribosome

39. Translation Assembling the Protein Chain 2. The first transfer RNA matches the messenger RNA’s first three nucleotides

40. Translation Assembling the Protein Chain 3. The larger ribosome subunit joins with the smaller subunit

41. Translation Assembling the Protein Chain 4. The second transfer RNA the second dock on the messenger RNA

42. Translation Assembling the Protein Chain 5. The backbones of the first two amino acid link

43. Translation Assembling the Protein Chain 6. The messenger RNA shifts to the right and the first transfer RNA drops off

44. Translation Assembling the Protein Chain 7. The next transfer RNA arrives to add the next amino acid

45. Translation Assembling the Protein Chain 8. One by one, triplets are read and the protein chain grows

46. Translation Assembling the Protein Chain 9. The final triplet signals “stop”. No transfer RNA fits here.

47. Translation Assembling the Protein Chain 10. The ribosome separates and drops off the messenger RNA

48. Translation Assembling the Protein Chain 11. For efficiency, the messenger RNA is read by more than one ribosome simultaneously

49. Translation Overview

50. Overview of Protein Synthesis

51. The Flow of Information DNA’s message is transcribed into RNA and RNA is translated into protein.

52. The Unity of Biology All living creatures - Use DNA and RNA to store and replicate information Make nucleotides using similar pathways Translate nucleotide chains into proteins using the same twenty amino acids and the same genetic code Use similar translation apparatus Have similar proteins

53. Examples of Nature’s Unity Locomotion The cilia that propel many single cell creatures also serve to protect our lungs by sweeping up dirt particles. Bones A bone that was once part of a reptile’s jaw has evolved into a device in the ear for transmitting sound waves.