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© 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor,

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Presentation on theme: "© 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor,"— Presentation transcript:

1 © 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey Chapter 3 The Molecules of Cells

2 INTRODUCTION TO ORGANIC COMPOUNDS © 2012 Pearson Education, Inc.

3 3.1 Lifes molecular diversity is based on the properties of carbon Diverse molecules found in cells are composed of carbon bonded to –other carbons and –atoms of other elements. Carbon-based molecules are called organic compounds. © 2012 Pearson Education, Inc.

4 3.1 Lifes molecular diversity is based on the properties of carbon By sharing electrons, carbon can –bond to four other atoms and –branch in up to four directions. Methane (CH 4 ) is one of the simplest organic compounds. –Four covalent bonds link four hydrogen atoms to the carbon atom. –Each of the four lines in the formula for methane represents a pair of shared electrons. © 2012 Pearson Education, Inc.

5 3.1 Lifes molecular diversity is based on the properties of carbon Methane and other compounds composed of only carbon and hydrogen are called hydrocarbons. Carbon, with attached hydrogens, can bond together in chains of various lengths. © 2012 Pearson Education, Inc.

6 Figure 3.1A Structural formula Ball-and-stick model Space-filling model The four single bonds of carbon point to the corners of a tetrahedron.

7 A carbon skeleton is a chain of carbon atoms that can be –branched or –unbranched. Compounds with the same formula but different structural arrangements are call isomers. 3.1 Lifes molecular diversity is based on the properties of carbon © 2012 Pearson Education, Inc. Animation: Isomers Animation: L-Dopa Animation: Carbon Skeletons

8 Figure 3.1B Length. Carbon skeletons vary in length. Ethane Propane Butane Isobutane Branching. Skeletons may be unbranched or branched. Double bonds. Skeletons may have double bonds. 1-Butene2-Butene Cyclohexane Benzene Rings. Skeletons may be arranged in rings.

9 Figure 3.1B_1 Length. Carbon skeletons vary in length. Ethane Propane

10 Figure 3.1B_2 Butane Isobutane Branching. Skeletons may be unbranched or branched.

11 Figure 3.1B_3 Double bonds. 1-Butene 2-Butene Skeletons may have double bonds.

12 Figure 3.1B_4 Cyclohexane Benzene Rings. Skeletons may be arranged in rings.

13 3.2 A few chemical groups are key to the functioning of biological molecules An organic compound has unique properties that depend upon the –size and shape of the molecule and –groups of atoms (functional groups) attached to it. A functional group affects a biological molecules function in a characteristic way. Compounds containing functional groups are hydrophilic (water-loving). © 2012 Pearson Education, Inc.

14 3.2 A few chemical groups are key to the functioning of biological molecules The functional groups are –hydroxyl groupconsists of a hydrogen bonded to an oxygen, –carbonyl groupa carbon linked by a double bond to an oxygen atom, –carboxyl groupconsists of a carbon double-bonded to both an oxygen and a hydroxyl group, –amino groupcomposed of a nitrogen bonded to two hydrogen atoms and the carbon skeleton, and –phosphate groupconsists of a phosphorus atom bonded to four oxygen atoms. © 2012 Pearson Education, Inc.

15 Table 3.2

16 Table 3.2_1

17 Table 3.2_2

18 3.2 A few chemical groups are key to the functioning of biological molecules An example of similar compounds that differ only in functional groups is sex hormones. –Male and female sex hormones differ only in functional groups. –The differences cause varied molecular actions. –The result is distinguishable features of males and females. © 2012 Pearson Education, Inc.

19 Figure 3.2_1 TestosteroneEstradiol

20 Figure 3.2_2

21 Figure 3.2_3

22 3.3 Cells make a huge number of large molecules from a limited set of small molecules There are four classes of molecules important to organisms: –carbohydrates, –proteins, –lipids, and –nucleic acids. © 2012 Pearson Education, Inc.

23 3.3 Cells make a huge number of large molecules from a limited set of small molecules The four classes of biological molecules contain very large molecules. –They are often called macromolecules because of their large size. –They are also called polymers because they are made from identical building blocks strung together. –The building blocks of polymers are called monomers. © 2012 Pearson Education, Inc.

24 3.3 Cells make a huge number of large molecules from a limited set of small molecules Monomers are linked together to form polymers through dehydration reactions, which remove water. Polymers are broken apart by hydrolysis, the addition of water. All biological reactions of this sort are mediated by enzymes, which speed up chemical reactions in cells. © 2012 Pearson Education, Inc. Animation: Polymers

25 A cell makes a large number of polymers from a small group of monomers. For example, –proteins are made from only 20 different amino acids and –DNA is built from just four kinds of nucleotides. The monomers used to make polymers are universal. 3.3 Cells make a huge number of large molecules from a limited set of small molecules © 2012 Pearson Education, Inc.

26 Figure 3.3A_s1 Short polymer Unlinked monomer

27 Figure 3.3A_s2 Short polymer Unlinked monomer Dehydration reaction forms a new bond Longer polymer

28 Figure 3.3B_s1

29 Figure 3.3B_s2 Hydrolysis breaks a bond

30 CARBOHYDRATES © 2012 Pearson Education, Inc. Carbohydrates range from small sugar molecules (monomers) to large polysaccharides. Glucose (an aldose) Fructose (a ketose)

31 Figure 3.4C Structural formula Abbreviated structure Simplified structure

32 Examples of Carbohydrates Monosaccharides: –Glucose, fructose, galactose –Range from 3 to 7 Carbons in length Disaccharides: –Maltose = Glucose---Glucose –Lactose = Glucose---Galactose –Sucrose = Glucose---Fructose Polysaccharides: –Long chains of monosaccharides –Glycogen, starch, cellulose are all long glucose chains © 2012 Pearson Education, Inc.

33 Function of Carbohydrates Carbohydrates are used as: –the main fuels for cellular work (immediate energy) –used as raw materials to manufacture other organic molecules. © 2012 Pearson Education, Inc.

34 Figure 3.5_s1 Glucose Monosaccharides can be linked together by a dehydration reaction

35 Figure 3.5_s2 Glucose Maltose Monosaccharides can be linked together by a dehydration reaction

36 Polysaccharides are long chains of sugar units Polysaccharides may function as –storage molecules or –structural compounds. Starch is used by plants for energy storage. Glycogen is used by animals for energy storage Cellulose forms plant cell walls. © 2012 Pearson Education, Inc.

37 Figure 3.7 Starch granules in potato tuber cells Glycogen granules in muscle tissue Glycogen Glucose monomer Starch Cellulose Hydrogen bonds Cellulose molecules Cellulose microfibrils in a plant cell wall

38 LIPIDS © 2012 Pearson Education, Inc.

39 3.8 Fats are lipids that are mostly energy-storage molecules Lipids –are water insoluble (hydrophobic, or water- fearing) compounds, –are important in long-term energy storage, –contain twice as much energy as a polysaccharide, and –consist mainly of carbon and hydrogen atoms linked by nonpolar covalent bonds. © 2012 Pearson Education, Inc.

40 3 Categories of Lipids We will consider three types of lipids: –Triglycerides (fats), –phospholipids, and –steroids. A triglyceride is a large lipid made from two kinds of smaller molecules, –glycerol and –3 fatty acids. © 2012 Pearson Education, Inc.

41 Figure 3.8B Fatty acid Glycerol Triglyceride = 1 glycerol covalently attached to 3 fatty acids

42 Figure 3.8C Fatty acids Glycerol Triglyceride = 1 glycerol covalently attached to 3 fatty acids Fatty acids can be: Saturated Unsaturated

43 Phospholipids Phospholipids contain two fatty acids attached to glycerol. –A phosphate functional group replaces the other fatty acid –Used to build cell membranes © 2012 Pearson Education, Inc.

44 Figure 3.9A-B Water Hydrophobic tails Water Hydrophilic heads Symbol for phospholipid Phosphate group Glycerol Phospholipids

45 Steroids and Cholesterol Steroids are lipids in which the carbon skeleton contains four fused rings. Cholesterol is a –common component in animal cell membranes and –starting material for making steroids, including sex hormones. © 2012 Pearson Education, Inc.

46 Figure 3.2 TestosteroneEstradiol

47 PROTEINS © 2012 Pearson Education, Inc.

48 Proteins are made from amino acids Proteins are –involved in nearly every function in your body and –very diverse, –50, ,000 proteins, each with a specific structure and function, in the human body. Proteins are composed of differing arrangements of a common set of just 20 amino acids. © 2012 Pearson Education, Inc. Amino group Carboxyl group

49 Proteins are made from amino acids Amino acids are classified as either –hydrophobic or hydrophilic. © 2012 Pearson Education, Inc. Hydrophobic Hydrophilic Aspartic acid (Asp) Serine (Ser)Leucine (Leu)

50 Figure 3.11C_s1 Carboxyl group Amino group Amino acid Amino acids are joined together by a dehydration reaction

51 Figure 3.11C_s2 Carboxyl group Amino group Amino acid Dipeptide Peptide bond Dehydration reaction Amino acids are joined together by a dehydration reaction

52 A proteins specific shape determines its function Proteins are distinguished by: –The combination of sequence of amino acids –The linear sequence of amino acids in a protein is called the PRIMARY STRUCTURE of the protein –3D structure The amino acid sequence causes the protein to assume a particular shape. The shape of a protein determines its specific function. © 2012 Pearson Education, Inc.

53 Figure 3.13A Primary structure Amino acid

54 Figure 3.13A-D_s4 Primary structure Amino acids Four Levels of Protein Structure Beta pleated sheet Alpha helix Hydrogen bond Secondary structure Tertiary structure Transthyretin polypeptide Quaternary structure Transthyretin, with four identical polypeptides

55 A proteins specific shape determines its function Functions of proteins: –Enzymes catalyze chemical reactions. –Structural proteins provide associations between body parts. –Contractile proteins are found within muscle. –Defensive proteins include antibodies of the immune system. –Signal proteins are best exemplified by hormones and other chemical messengers. –Receptor proteins transmit signals into cells. –Transport proteins carry oxygen. –Storage proteins serve as a source of amino acids for developing embryos. © 2012 Pearson Education, Inc.

56 NUCLEIC ACIDS © 2012 Pearson Education, Inc.

57 3.14 DNA and RNA are the two types of nucleic acids DNA(deoxyribonucleic acid) –DNA is provides genetic information –DNA is inherited from an organisms parents. –DNA provides instructions for production of proteins in a cell. DNA works through an intermediary, ribonucleic acid (RNA). –DNA is transcribed into RNA. –RNA is translated into proteins. © 2012 Pearson Education, Inc.

58 Figure 3.14_s1 Gene DNA

59 Figure 3.14_s2 Gene DNA Transcription RNA Nucleic acids

60 Figure 3.14_s3 Gene DNA Transcription RNA Protein Translation Amino acid Nucleic acids

61 Nucleic acids are built from nucleotides Phosphate group Sugar Nitrogenous base (adenine) Nucleotides have three parts: –a five-carbon sugar called ribose in RNA and deoxyribose in DNA, –a phosphate group, and –a nitrogenous base.

62 DNA vs. RNA DNA nitrogenous bases are –adenine (A), –thymine (T), –cytosine (C), and –guanine (G). DNA sugar = deoxyribose RNA –also has A, C, and G, –but instead of T, it has uracil (U). RNA sugar = ribose © 2012 Pearson Education, Inc.

63 Figure 3.15B A T C G T Nucleotide Sugar-phosphate backbone

64 DNA vs. RNA DNA = 2 strands of nucleotides that form a double helix. –The two strands pair thru contacts with nucleotide bases –A pairs with T –C pairs with G RNA is usually a single polynucleotide strand. © 2012 Pearson Education, Inc.

65 Figure 3.15C Base pair A C T G C CG T A CG A T T A G C T A T A A T

66 Figure 3.UN01 Short polymer Monomer Dehydration Hydrolysis Longer polymer

67 Figure 3.UN03_1 Carbohydrates Monosaccharides Lipids (dont form polymers) Glycerol Components of a fat molecule Fatty acid f. Hormones e. Phospholipids Plant cell support Starch, glycogen Energy for cell, raw material Functions Examples Classes of Molecules and Their Components b. a. c. d. Energy storage

68 Figure 3.UN03_2 Functions Examples Classes of Molecules and Their Components Proteins g.h. i. Nucleic Acids Amino acid o. q. Nucleotide s. Receive signals DNA and RNA Receptor protein Heredity Storage Egg albumin Antibodies Signal proteins Muscles Hair, tendons Lactase Transport Communication n. l. j. m. r. p. k.


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