General Biology 1004 Chapter 3 Lecture Handout, Summer 2005 Dr. Frisby

Transcription

1 Slide 1 CHAPTER 3 The Molecules of Life PowerPoint Lecture Slides for Essential Biology, Second Edition & Essential Biology with Physiology Presentation prepared by Chris C. Romero Copyright 2004 Pearson Education, Inc. publishing as Benjamin Cummings Neil Campbell, Jane Reece, and Eric Simon Slide 2 BIOLOGY AND SOCIETY: GOT LACTOSE? Milk is among the healthier foods you can eat It is rich in many nutrients But milk-containing foods make some people ill This is called lactose intolerance Slide 3 People who are lactose intolerant do not produce enough of the enzyme lactase Their cells cannot break down and absorb lactose Lactose intolerance can be managed by Figure 3.1

2 Slide 4 ORGANIC MOLECULES A cell is mostly water The rest of the cell consists mostly of carbon -based molecules Organic chemistry is Slide 5 Carbon Chemistry Carbon is a versatile atom Slide 6 Carbon can use its bonds to Attach to other carbons Form an endless diversity of carbon skeletons Carbon skeletons vary in length Carbon skeletons may be unbranched or branched Carbon skeletons may have double bonds, which can vary in location Figure 3.2 Carbon skeletons may be arranged in rings

3 Slide 7 The simplest organic compounds are hydrocarbons Structural formula Ball-and-stick model Space-filling model Figure 3.3 Slide 8 Larger hydrocarbons Are the main molecules in the gasoline we burn in our cars The hydrocarbons of fat molecules provide energy for our bodies Figure 3.4 Slide 9 Each type of organic molecule has a unique three-dimensional shape that defines its function in an organism Receptor molecule Transmitting cell Receiving cell Signal molecule Figure 3.5

4 Slide 10 The unique properties of an organic compound depend not only on its carbon skeleton but also on the atoms attached to the skeleton Slide 11 Some common functional s Hydroxyl Carbonyl Amino Carboxyl Found in alcohols and sugars Found in sugars Found in amino acids and urea in urine (from protein breakdown) Found in amino acids, fatty acids, and some vitamins Figure 3.6 Slide 12 Giant Molecules from Smaller Building Blocks On a molecular scale, many of life s molecules are gigantic

5 Slide 13 Most macromolecules are polymers Short polymer Monomer Longer polymer (a) Dehydration synthesis of a polymer Figure 3.7A Slide 14 Organisms also have to break down macromolecules (b) Hydrolysis of a polymer Figure 3.7B Slide 15 BIOLOGICAL MOLECULES There are four categories of large molecules in cells Carbohydrates Lipids Proteins Nucleic acids

6 Slide 16 Carbohydrates Carbohydrates include Slide 17 Monosaccharides are simple sugars Monosaccharides Honey contains both glucose and fructose Figure 3.8 Slide 18 The monosaccharides glucose and fructose are isomers Glucose Fructose Figure 3.9

7 Slide 19 In aqueous solutions, monosaccharides form rings Monosaccharides are the main fuel that cells use for cellular work (b) Abbreviated ring structure (a) Linear and ring structures Figure 3.10 Slide 20 Glucose Slide 21 Disaccharides A disaccharide is a double sugar

8 Slide 22 Disaccharides are joined by the process of dehydration synthesis Glucose Glucose Maltose Figure 3.11 Slide 23 The most common disaccharide is sucrose, common table sugar Slide 24 The United States is one of the world s leading markets for sweeteners The average American consumes about 64 kg of sugar per year Figure 3.12

9 Slide 25 Polysaccharides Complex carbohydrates are called polysaccharides Slide 26 Polysaccharides (a) Starch Starch granules in potato tuber cells Glycogen Granules In muscle tissue Glucose monomer (b) Glycogen Cellulose fibril in a plant cell wall Cellulose molecules (c) Cellulose Figure 3.13 Slide 27 One familiar example of a polysaccharide is starch

10 Slide 28 Animals store excess sugar in the form of a polysaccharide called glycogen Glycogen is similar in structure to starch Slide 29 Cellulose is the most abundant organic compound on Earth Slide 30 Most animals cannot derive nutrition from fiber How do grazing animals survive on a diet of cellulose? Figure 3.14

11 Slide 31 Simple sugars and double sugars dissolve readily in water Slide 32 Lipids Lipids are hydrophobic Slide 33 Fats Dietary fat consists largely of the molecule triglyceride Fatty acid Glycerol (a) Dehydration synthesis linking a fatty acid to glycerol Figure 3.15a

12 Slide 34 Fats perform essential functions in the human body Slide 35 Unsaturated fatty acids Saturated fatty acids Slide 36 (b) A fat molecule Figure 3.15B

13 Slide 37 Most animal fats have a high proportion of saturated fatty acids Example: butter Most plant oils tend to be low in saturated fatty acids Example: corn oil Slide 38 Steroids Steroids are very different from fats in structure and function The carbon skeleton is bent to form four fused rings Cholesterol is the Cholesterol base steroid from which your body produces other steroids Testosterone Example: sex A type of estrogen hormones Figure 3.16 Slide 39 Synthetic anabolic steroids are controversial Figure 3.17

14 Slide 40 Proteins A protein is a polymer constructed from amino acid monomers Proteins perform most of the tasks the body needs to function Slide 41 Types of proteins (b) Storage proteins (d) Transport proteins (a) Structural proteins (c) Contractile proteins Figure 3.18 Slide 42 The Monomers: Amino Acids All proteins are constructed from a common set of 20 kinds of amino acids

15 Slide 43 Each amino acid consists of Amino Carboxyl (a) Side Side s (b) Leucine (hydrophobic) Serine (hydrophobic) Figure 3.19 Slide 44 Cells link amino acids together by dehydration synthesis Proteins as Polymers Side Carboxyl Amino acid Amino Side Amino acid Dehydration synthesis Side Side Peptide bond Figure 3.20 Slide 45 Your body has tens of thousands of different kinds of protein

16 Slide Primary structure Figure 3.21 Amino acid Slide 47 A slight change in the primary structure of a protein affects its ability to function The substitution of one amino acid for another in hemoglobin causes sickle -cell disease (a) Normal red blood cell Normal hemoglobin (b) Sickled red blood cell Sickle-cell hemoglobin Figure 3.22 Slide 48 Protein Shape Proteins have four levels of structure Hydrogen bond Amino acid (a) Primary structure Pleated sheet Polypeptide (single subunit) Hydrogen bond Alpha helix (b) Secondary structure (c) Tertiary structure Complete protein, with four polypeptide subunits (d) Quaternary structure Figure 3.23

17 Slide 49 What Determines Protein Structure? A protein s shape is sensitive to the surrounding environment Slide 50 Nucleic Acids Nucleic acids are information storage molecules Slide 51 There are two types of nucleic acids DNA, deoxyribonucleic acid RNA, ribonucleic acid

18 Slide 52 Nucleic acids are polymers of nucleotides Nitrogenous base (A,G,C, or T) Thymine (T) Phosphate Sugar (deoxyribose) Phosphate Base Sugar Figure 3.24 Slide 53 Each DNA nucleotide has one of the following bases Thymine (T) Cytosine (C) Adenine (A) Guanine (G) Figure 3.25 Slide 54 Nucleotide monomers are linked into long chains Backbone Nucleotide Bases (a) DNA strand Figure 3.26a

19 Slide 55 Two strands of DNA join together to form a double helix Base pair (b) Double helix Figure 3.26b Slide 56 RNA, ribonucleic acid, is different from DNA Nitrogenous base (A,G,C, or U) Uracil (U) Phosphate Sugar (ribose) Figure 3.27 Slide 57 EVOLUTION CONNECTION: DNA AND PROTEINS AS EVOLUTIONARY TAPE MEASURES Evolutionary relationships between organisms can be assessed Molecular genealogy extends to relationships between species Biologists use molecular analysis of DNA and protein sequences for testing evolutionary hypotheses

20 Slide 58 Gibbon Gorilla Human Frog Mouse Rhesus monkey Millions of years ago Last common ancestor lived 26 million years ago based on fossil evidence Amino acid differences compared with human hemoglobin Figure 3.28 Chapter 3 Study Objectives 1. Explain the cause of lactose intolerance and how the condition can be treated. 2. Describe the special bonding properties of carbon that allow it to form an endless variety of organic molecules. 3. Compare the process of dehydration synthesis and hydrolysis. 4. Compare the structure of monosaccharides, disaccharides, and polysaccharides. Give an example of each. 5. Compare the structure and properties of saturated and unsaturated fatty acids. 6. Distinguish between steroids and anabolic steroids, and explain how anabolic steroids can be dangerous to a person s health. 7. Describe the structure of proteins. Distinguish between the primary structure and the final three-dimensional shape. 8. Describe the structure of DNA, and explain how it is replicated. 9. Explain how the structure of DNA can be used to test evolutionary relationaships of organisms.