1. 1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. PowerPoint to accompany CONCEPTS IN BIOLOGY TWELFTH EDITION Enger Ross Bailey CHAPTER 3

2. 2 3.1 Organic chemistry All organic molecules contain carbon. – Inorganic molecules do not contain carbon. Biochemistry is the chemistry of living things.

3. 3 Carbon: The central atom Carbon is the central atom in all organic molecules. Carbon has unique bonding properties. – Can combine with other carbon atoms in long chains. – Can form ring structures.

4. 4 Carbon: The central atom Carbon atoms participate in four covalent bonds. – Has four electrons in the outer energy level. – Can double bond with oxygen. – Can triple bond with other carbon atoms. (e.g., gas acetylene, C 2 H 2, Hydrogen cyanid, HCN) (See page 47)

5. 5 Isomers (See p. 47) Several factors determine the properties of an organic molecule. – The types of atoms in the molecule. – The 3-D arrangement of atoms within the molecule. Organic molecules can have the same number and composition of atoms, but can have different arrangements. – These are called isomers. Molecules with the same empirical formula but different structural formulas.

6. 6 Hexose isomers (i.e., Structure isomers)

7. How Science Works 3.1 (See p. 50) Generic Drugs and Mirror Image Isomers

8. The carbon skeleton All organic molecules have a carbon skeleton. – This determines the overall shape of the molecule. Organic molecules differ in these ways: – The length and arrangement of the carbon skeleton. – The kinds and location of atoms attached to it. – How the attached atoms are combined together These combinations are called functional groups. Functional groups determine the chemical nature of the molecule.

9. Functional groups

10. 10 Macromolecules of life Macromolecules are very large organic molecules. The most important organic compounds found in living things are: Carbohydrates Proteins Nucleic acids Lipids

11. Polymers Carbohydrates, proteins and nucleic acids are polymers. Polymers are combinations of smaller building blocks. – The building blocks are called monomers. Polymers are built via dehydration synthesis. Polymers are broken apart via hydrolysis.

12. 12 3.2 Carbohydrates Organic molecules composed of carbon, hydrogen and oxygen. All have the general formula CH 2 O. Names end in –ose. (See p. 49 in Textbook) Serve as the primary energy source for most living things. Also serve as structural support – Plant cell walls Important components of nucleic acids – DNA

13. 13 Simple sugars Simple sugars are described by the number of carbons in the molecule. – Triose-3 carbons – Pentose-5 carbons – Hexose-6 carbons Examples of simple sugars: – Glucose – Fructose – Galactose

14. 14 Complex carbohydrates When two or more simple sugars are combined they form complex carbohydrates. – Formed via dehydration synthesis Disaccharides – Two simple sugars Sucrose Lactose Maltose Trisaccharides – Three simple sugars

16. Polysaccharides Contain many simple sugars Examples of polysaccharides: – Starch and glycogen Used for energy storage in plants (starch) and animals (glycogen, (i.e., animal starch)) – Cellulose Important component of plant cell walls. Humans cannot digest cellulose; it is the fiber in our diet. – Helps facilitate movement of food through the digestive tract.

17. 17 Complex carbohydrates

18. 18 3.3 Proteins Proteins are polymers made of amino acids. An amino acid contains: – Central carbon – Amino group – Carboxyl group – Hydrogen There are 20 different amino acids. (See p. 53 Outlooks 3.2)

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20. 20 The structure of proteins Amino acids are joined via dehydration synthesis. – The bond formed between amino acids is called a peptide bond. Several amino acids joined together form polypeptide chains.

21. 21 Primary structure The sequence of amino acids in a polypeptide constitutes the primary structure of the protein. This sequence is dictated by information in genes (DNA). All levels of protein structure depend on the primary sequence.

22. Secondary structure Polypeptides twist and fold into their secondary structure. – Some sequences of amino acids twist into a helix. This is called an alpha helix. – Some sequences of amino acids remain straight and fold back on themselves. This is called a beta-pleated sheet.

23. 23 Tertiary structure The various alpha helices and beta pleated sheets interact to form a globular structure. This globular structure is unique for each polypeptide.

24. Quaternary structure Some proteins contain more than one polypeptide chain. Each of these polypeptides has its own unique tertiary structure. – These polypeptides interact to form a more complex globular structure. Quaternary structure can be stabilized by disulfide bonds. (see next page)

26. Form and function The protein’s overall shape determines its job. If a protein is not shaped properly, it likely will not work properly. Example: – Sickle cell anemia (See p.54, p. 159) – A mutation in the gene causes the protein to have a different shape. (Point mutation, see p. 158)) – This shape change results in a change in function. (CJD &BSE, p. 56) Denaturation: – When heat or other environmental conditions break the bonds that stabilize tertiary structure. (See p. 56)

27. 27 Types of proteins Structural proteins – Important in maintaining the shape of cells and organisms. – Collagen Regulatory proteins – Determine what activities will occur in a protein. – Enzymes and hormones Carrier proteins – Transport molecules from one place to another. – Lipoproteins

28. 28 3.4 Nucleic acids The complex organic polymer molecules. Store and transfer information within a cell. Include DNA and RNA Are made of nucleotides. – 5-carbon sugar – phosphate group – nitrogenous group.

29. 29 Nucleotides

30. 30 DNA vs. RNA

31. 31 DNA Each DNA molecule is made of two strands. – Held together by hydrogen bonds between the nitrogenous bases. – The bases pair according to base pair rules. (See Fig. 3.17) Adenine - thymine Cytosine - guanine The two DNA strands are twisted on each other, forming a double helix. (See Fig. 3.17) Each DNA strand is divided into segments. (See p.57) – Each segment forms a gene. (p. 57,Book, chapter) – Genes are the recipes for proteins. The sequence of nucleotides in a gene dictate the order of amino acids in a polypeptide.

32. 32 The structure of DNA

33. 33 DNA and chromosomes Each DNA strand has many genes. Each DNA strand is called a chromosome. Human cells have 46 chromosomes in each cell. – Each cell copies all of these chromosomes before it divides to pass along to daughter cells.

34. 34 The functions of DNA DNA is able to: – Replicate itself – Mutate (change chemically) – Store information and transmit it to offspring – Direct synthesis of proteins

36. 36 RNA RNA is a single stranded molecule. Contains uracil instead of thymine. Base pairs with itself and DNA – A-U – G-C RNA is found in three different forms: mRNA (messenger RNA) rRNA (ribosomal RNA) tRNA (transfer RNA)

38. 38 3.5 Lipids Commonly called fats. Large and nonpolar – Do not dissolve in water – Dissolve in other nonpolar molecules like acetone Usually have very few oxygen atoms There are three types of lipids: – True fats (e.g. pork chop fat and oils) – Phospholipids (membrane components) – Steroids (most hormones)

39. 39 True (neutral) fats Used to provide energy. The building blocks of fats – A glycerol molecule – Three fatty acids.

40. 40 Saturated vs. unsaturated lipids If the carbon skeleton of a fatty acid has as much hydrogen as possible, the fat is called a saturated fat. – Saturated fats are found in animal tissues and tend to be solid at room temperature. If the carbons of a fat have double bonded carbon molecules in them, the fat is called unsaturated fat. – Unsaturated fats are frequently plant fats and are liquids at room temperature. – A polyunsaturated fat has several double bonds. – Fats are important energy storage molecules.

41. 41 Saturated and unsaturated fatty acids

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47. 47 Phospholipids Are complex organic molecules that resemble fats but contain phosphate groups. Phospholipids are the major components of cell membranes. – Some are known as lecithins. (See p.62, p. 63 Outlooks)

48. Diagram of a Lipoprotein

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50. 50 December 4, 2006 (New York Times) End of Drug Trial Is a Big Loss for Pfizer By ALEX BERENSON The news came to Pfizer ’ s chief scientist, Dr. John L. LaMattina, as he was showering at 7 a.m. Saturday: the company ’ s most promising experimental drug, intended to treat heart disease, actually caused an increase in deaths and heart problems. Eighty-two people had died so far in a clinical trial, versus 51 people in the same trial who had not taken it. Within hours, Pfizer, the world ’ s largest drug maker, told more than 100 trial investigators to stop giving patients the drug, called torcetrapib. Shortly after 9 p.m. Saturday, Pfizer announced that it had pulled the plug on the medicine entirely, turning the company ’ s nearly $1 billion investment in it into a total loss. Pfizer's shares fell by 10.6% to $24.90 by the close of trade on Wall Street.

51. 51 Steroids Nonpolar molecules that are arranged in rings of carbon. Steroids are important components of cell membranes. – Cholesterol (See p.62) Steroids often serve as hormones and serve in regulation of body processes. – Testosterone