1. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb PowerPoint ® Lecture Slides prepared by Vince Austin, University of Kentucky 2 Chemistry Comes Alive Part B

2. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Biochemistry  Organic compounds  Contain carbon, are covalently bonded, and are often large  Inorganic compounds  Do not contain carbon  Water, salts, and many acids and bases

3. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Properties of Water  High heat capacity – absorbs and releases large amounts of heat before changing temperature  High heat of vaporization – changing from a liquid to a gas requires large amounts of heat  Polar solvent properties – dissolves ionic substances, forms hydration layers around large charged molecules, and serves as the body’s major transport medium

4. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Properties of Water  Reactivity – is an important part of hydrolysis and dehydration synthesis reactions  Cushioning – resilient cushion around certain body organs

5. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Acids and Bases  Acids release H + and are therefore proton donors HCl  H + + Cl –  Bases release OH – and are proton acceptors NaOH  Na + + OH –

6. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Acid-Base Concentration (pH)  Acidic solutions have higher H + concentration and therefore a lower pH  Alkaline solutions have lower H + concentration and therefore a higher pH  Neutral solutions have equal H + and OH – concentrations

7. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Acid-Base Concentration (pH)  Acidic: pH 0–6.99  Basic: pH 7.01–14  Neutral: pH 7.00 Figure 2.12

8. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Buffers  Systems that resist abrupt and large swings in the pH of body fluids  Carbonic acid-bicarbonate system  Carbonic acid dissociates, reversibly releasing bicarbonate ions and protons  The chemical equilibrium between carbonic acid and bicarbonate resists pH changes in the blood

9. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Organic Compounds  Molecules unique to living systems contain carbon and hence are organic compounds  They include:  Carbohydrates  Lipids  Proteins  Nucleic Acids

10. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Carbohydrates Figure 2.13a  Contain carbon, hydrogen, and oxygen  Their major function is to supply a source of cellular food  Examples:  Monosaccharides or simple sugars

11. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Carbohydrates Figure 2.13b  Disaccharides or double sugars

12. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

13. Carbohydrates Figure 2.13c  Polysaccharides or polymers of simple sugars

14. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Lipids  Contain C, H, and O, but the proportion of oxygen in lipids is less than in carbohydrates  Examples:  Neutral fats or triglycerides  Phospholipids  Steroids

15. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Neutral Fats (Triglycerides) Figure 2.14a  Composed of three fatty acids bonded to a glycerol molecule

16. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Other Lipids Figure 2.14b  Phospholipids – modified triglycerides with two fatty acid groups and a phosphorus group

17. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

18. Other Lipids Figure 2.14c  Steroids – flat molecules with four interlocking hydrocarbon rings

19. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Representative Lipids Found in the Body  Neutral fats – found in subcutaneous tissue and around organs  Phospholipids – chief component of cell membranes  Steroids – cholesterol, sex hormones, and adrenal cortical hormones  Fat-soluble vitamins – vitamins A,D, E, and K  Lipoproteins – transport fatty acids and cholesterol in the bloodstream

20. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Amino Acids  Building blocks of protein, containing an amino group and a carboxyl group  Amino acid structure

21. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Amino Acids Figure 2.15a-c

22. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Protein Figure 2.16  Macromolecules composed of combinations of 20 types of amino acids bound together with peptide bonds

23. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Structural Levels of Proteins  Primary – amino acid sequence  Secondary – alpha helices or beta pleated sheets  Tertiary – superimposed folding of secondary structures  Quaternary – polypeptide chains linked together in a specific manner

24. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Structural Levels of Proteins Figure 2.17a-c

25. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Structural Levels of Proteins Figure 2.17d, e

26. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Fibrous and Globular Proteins  Fibrous proteins  Extended and strandlike proteins  Examples: keratin, elastin, collagen, and certain contractile fibers  Globular proteins  Compact, spherical proteins with tertiary and quaternary structures  Examples: antibodies, hormones, and enzymes

27. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Protein Denuaturation Figure 2.18a  Reversible unfolding of proteins due to drops in pH and/or increased temperature

28. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Protein Denuaturation Figure 2.18b  Irreversibly denatured proteins cannot refold and are formed by extreme pH or temperature changes

29. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Characteristics of Enzymes  Most are globular proteins that act as biological catalysts  Holoenzymes consist of an apoenzyme (protein) and a cofactor (usually an ion)  Enzymes are chemically specific  Frequently named for the type of reaction they catalyze  Enzyme names usually end in -ase  Lower activation energy

30. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Characteristics of Enzymes Figure 2.19

31. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Mechanism of Enzyme Action  Enzyme binds with substrate  Product is formed at a lower activation energy  Product is released

32. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Enzyme- substrate complex (E–S) 1 2 3 Internal rearrangements leading to catalysis Free enzyme (E) Active site Enzyme (E) Substrates (s) Amino acids H20H20 Peptide bond Dipeptide product (P) Mechanism of Enzyme Action Figure 2.20

33. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Nucleic Acids  Composed of carbon, oxygen, hydrogen, nitrogen, and phosphorus  Their structural unit, the nucleotide, is composed of N-containing base, a pentose sugar, and a phosphate group  Five nitrogen bases contribute to nucleotide structure – adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U)  Two major classes – DNA and RNA

34. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Deoxyribonucleic Acid (DNA)  Double-stranded helical molecule found in the nucleus of the cell  Replicates itself before the cell divides, ensuring genetic continuity  Provides instructions for protein synthesis

35. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Structure of DNA Figure 2.21a

36. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Structure of DNA Figure 2.21b

37. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

38. Ribonucleic Acid (RNA)  Single-stranded molecule found in both the nucleus and the cytoplasm of a cell  Uses the nitrogenous base uracil instead of thymine  Three varieties of RNA: messenger RNA, transfer RNA, and ribosomal RNA

39. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.40 Information transfer from DNA to RNA to polypeptide. DNA: DNA base sequence (triplets) of the gene codes for synthesis of a Particular polypeptide chain DNA molecule Gene 1 Gene 2 Codons Triplets Anticodon tRNA Stop; detach Start translation mRNA: Base sequence (codons) of the transcribed mRNA tRNA: Consecutive base sequences of tRNA anticodons recognize the mRNA codons calling for the amino acids they transport Polypeptide: Amino acid sequence of the polypeptide chain Gene 4 12 3 4 56 7 89 12 3 4 56 7 89

40. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.37 Translation is the process in which genetic information carried by an mRNA is decoded in the ribosome to form a particular polypeptide. Slide 1 Elongation. Amino acids are added one at a time to the growing peptide chain via a process that has three repeating steps. 2 Amino acid corresponding to anticodon Template strand of DNA Pre-mRNA mRNA Nucleus (site of transcription) Amino acid corresponding to anticodon Met tRNA The correct amino acid is attached to each species of tRNA by a synthetase enzyme. Ile Pro Leu tRNA anticodon Polypeptide Ile Pro Complementary mRNA codon Leu New peptide bond Released tRNA Pro Leu Ile A P E A P E Peptide bond formation. The growing polypeptide bound to the tRNA at the P site is transferred to the amino acid carried by the tRNA in the A site, and a new peptide bond is formed. 2b 2c Translocation. As the entire ribosome translocates, it shifts by one codon along the mRNA: The unloaded tRNA in the P site is moved to the E site and then released. The tRNA in the A site moves to the P site. The next codon to be translated is now in the empty A site ready for step 2a again. Direction of ribosome movement Polypeptide Release factor Stop codon P E Termination. When a stop codon (UGA, UAA, or UAG) arrives at the A site, elongation ends. Release of the newly made polypeptide is triggered by a release factor and the ribosomal subunits separate, releasing the mRNA. 3 Codon recognition. The anticodon of an incoming tRNA binds with the complementary mRNA codon (A to U and C to G) in the A site of the ribosome. 2a Small ribosomal subunit Start codon A site P site E site Initiation. Initiation occurs when four components combine: A small ribosomal subunit An initiator tRNA that carries the amino acid methionine The mRNA A large ribosomal subunit Once this is accomplished, the next phase, elongation, begins. 1 Initiator tRNA bearing anticodon Aminoacyl-tRNA synthetase Met Cytosol (site of translation) Met Newly made (and edited) mRNA leaves nucleus and travels to a free or attached ribosome for decoding. Methionine (amino acid) Large ribosomal subunit U A C U A C C C C U A U U U A A G G A P E GGC GGC GAU GAU G A U ACCCU A ACCGCUCUC ACUGGGU G A CC U GAUACCCUA G A U G G C G A C

41. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Adenosine Triphosphate (ATP)  Source of immediately usable energy for the cell  Adenine-containing RNA nucleotide with three phosphate groups

42. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Adenosine Triphosphate (ATP) Figure 2.22

43. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings How ATP Drives Cellular Work Figure 2.23

44. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings A substance that is very acidic may have a pH of 1 or 2. This means that the acidic substance __________.  has a high concentration of OH – ions  has an equal concentration of OH – and H + ions  has a low concentration of H + ions  has a high concentration of H + ions

45. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings A buffer resist a change in pH  True  False

46. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The four major organic compounds that comprise our bodies are __________.  water, salt, carbon, oxygen  proteins, carbohydrates, lipids, nucleic acids  amino acids, fats, sugars, DNA  carbon, hydrogen, oxygen, nitrogen

47. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The major building blocks of carbohydrates are __________.  amino acids  fats  nucleotides  monosaccharides

48. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The three subclasses of lipids include phospholipids, steroids, and __________.  fatty acids  glycerols  triglycerides  oils

49. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The major building block for proteins is __________.  amino acids  monosaccharides  triglycerides  nucleotides

50. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings An enzyme’s ____________ is the molecule upon which an enzyme acts.  active site  substrate  inhibitor  catalyst

51. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Increasing the concentration of an enzyme’s substrate (up to a point) would ___________ the reaction.  slow down  speed up  inhibit  destroy

52. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The major building blocks of nucleic acids are __________.  amino acids  DNA and RNA  nucleotides  sugars

53. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The four DNA nucleotides are __________.  carbon, hydrogen, nitrogen, oxygen  protein, lipid, nucleic acid, carbohydrate  primary, secondary, tertiary, quaternary  adenine, thymine, cytosine, guanine