PowerPoint Lectures Campbell Biology: Concepts & Connections, Eighth Edition REECE TAYLOR SIMON DICKEY HOGAN Chapter 3 Lecture by Edward J. Zalisko The Molecules of Cells © 2015 Pearson Education, Inc.

Introduction Most of the world’s population cannot digest milk- based foods. These people are lactose intolerant, because they lack the enzyme lactase. This illustrates the importance of biological molecules, such as lactase, in the daily functions of living organisms. © 2015 Pearson Education, Inc.

Figure Chapter 3: Big Ideas Introduction to Organic Compounds Carbohydrates Lipids ProteinsNucleic Acids

I NTRODUCTION TO O RGANIC C OMPOUNDS © 2015 Pearson Education, Inc.

3.1 Life’s molecular diversity is based on the properties of carbon Almost all the molecules a cell makes are composed of carbon bonded to other carbons and atoms of other elements. Carbon-based molecules are called organic compounds. © 2015 Pearson Education, Inc.

3.1 Life’s 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. © 2015 Pearson Education, Inc.

Figure 3.1a The four single bonds of carbon point to the corners of a tetrahedron. H H H H C

3.1 Life’s 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 form chains of various lengths. © 2015 Pearson Education, Inc.

3.1 Life’s molecular diversity is based on the properties of carbon A carbon skeleton is a chain of carbon atoms that can differ in length and be straight, branched, or arranged in rings. © 2015 Pearson Education, Inc.

3.1 Life’s molecular diversity is based on the properties of carbon Compounds with the same formula but different structural arrangements are called isomers. © 2015 Pearson Education, Inc.

Animation: L -Dopa © 2015 Pearson Education, Inc.

Animation: Carbon Skeletons © 2015 Pearson Education, Inc.

3.2 A few chemical groups are key to the functioning of biological molecules The unique properties of an organic compound depend on the size and shape of its carbon skeleton and the groups of atoms that are attached to that skeleton. The sex hormones testosterone and estradiol (a type of estrogen) differ only in the groups of atoms highlighted in Figure 3.2. © 2015 Pearson Education, Inc.

Figure TestosteroneEstradiol

3.2 A few chemical groups are key to the functioning of biological molecules Table 3.2 illustrates six chemical groups important in the chemistry of life. The first five groups are called functional groups; they affect a molecule’s function in a characteristic way. These five groups are polar, so compounds containing them are typically hydrophilic (water- loving) and soluble in water. © 2015 Pearson Education, Inc.

3.2 A few chemical groups are key to the functioning of biological molecules A sixth group, a methyl group, consists of a carbon bonded to three hydrogen atoms, is nonpolar and not reactive, but still affects molecular shape and thus function. © 2015 Pearson Education, Inc.

Table 3.2-0

3.2 A few chemical groups are key to the functioning of biological molecules The functional groups are hydroxyl group—a hydrogen bonded to an oxygen, carbonyl group—a carbon linked by a double bond to an oxygen atom, carboxyl group—a carbon double-bonded to both an oxygen and a hydroxyl group, amino group—a nitrogen bonded to two hydrogen atoms and the carbon skeleton, and phosphate group—a phosphorus atom bonded to four oxygen atoms. © 2015 Pearson Education, Inc.

3.3 Cells make large molecules from a limited set of small molecules There are four classes of molecules important to organisms: 1.carbohydrates, 2.lipids, 3.proteins, and 4.nucleic acids. © 2015 Pearson Education, Inc.

3.3 Cells make 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 or similar building blocks strung together. The building blocks of polymers are called monomers. © 2015 Pearson Education, Inc.

3.3 Cells make 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. These reactions are mediated by enzymes, specialized macromolecules that speed up chemical reactions in cells. © 2015 Pearson Education, Inc.

Animation: Polymers © 2015 Pearson Education, Inc.

3.3 Cells make large molecules from a limited set of small molecules 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 monomers called nucleotides. The monomers used to make polymers are essentially universal. © 2015 Pearson Education, Inc.

Figure Short polymer Unlinked monomer Dehydration reaction forms a new bond H2OH2O Longer polymer Hydrolysis breaks a bond H2OH2O

© 2015 Pearson Education, Inc. Figure Short polymer Unlinked monomer

© 2015 Pearson Education, Inc. Figure Short polymer Unlinked monomer Dehydration reaction forms a new bond H2OH2O Longer polymer

© 2015 Pearson Education, Inc. Figure

© 2015 Pearson Education, Inc. Figure Hydrolysis breaks a bond H2OH2O

C ARBOHYDRATES © 2015 Pearson Education, Inc.

Start filling out your Organic Compound Chart © 2015 Pearson Education, Inc.

3.4 Monosaccharides are the simplest carbohydrates Carbohydrates range from small sugar molecules (monomers) to large polysaccharides. Sugar monomers are monosaccharides, such as those found in fructose, glucose, and honey. © 2015 Pearson Education, Inc.

Figure 3.4a

3.4 Monosaccharides are the simplest carbohydrates Monosaccharides can be hooked together by dehydration reactions to form more complex sugars and polysaccharides. © 2015 Pearson Education, Inc.

3.4 Monosaccharides are the simplest carbohydrates The carbon skeletons of monosaccharides vary in length. Monosaccharides are the main fuels for cellular work and used as raw materials to manufacture other organic molecules. © 2015 Pearson Education, Inc.

Figure 3.4b GlucoseFructose

© 2015 Pearson Education, Inc. Figure 3.4c Structural formula Abbreviated structure Simplified structure 3.4 Monosaccharides are the simplest carbohydrates Many monosaccharides form rings. The ring diagram may be drawn as:

3.5 Two monosaccharides are linked to form a disaccharide Two monosaccharides (monomers) can bond to form a disaccharide in a dehydration reaction. The disaccharide sucrose is formed by combining a glucose monomer and a fructose monomer. The disaccharide maltose is formed from two glucose monomers. © 2015 Pearson Education, Inc.

Animation: Disaccharides © 2015 Pearson Education, Inc.

Figure Glucose

© 2015 Pearson Education, Inc. Figure Glucose Maltose H2OH2O What is it called when water is removed from something?

3.7 Polysaccharides are long chains of sugar units Polysaccharides are macromolecules, polymers composed of thousands of monosaccharides. Polysaccharides may function as storage molecules or structural compounds. © 2015 Pearson Education, Inc.

3.7 Polysaccharides are long chains of sugar units Starch is a polysaccharide, composed of glucose monomers, and used by plants for energy storage. Glycogen is a polysaccharide, composed of glucose monomers, and used by animals for energy storage. © 2015 Pearson Education, Inc.

3.7 Polysaccharides are long chains of sugar units Cellulose is a polymer of glucose and forms plant cell walls. Chitin is a polysaccharide, used by insects and crustaceans to build an exoskeleton, and found in the cell walls of fungi. © 2015 Pearson Education, Inc.

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

3.7 Polysaccharides are long chains of sugar units Polysaccharides are usually hydrophilic (water- loving). Bath towels, for example, are often made of cotton, which is mostly cellulose, and therefore water absorbent. © 2015 Pearson Education, Inc.

Animation: Polysaccharides © 2015 Pearson Education, Inc.

L IPIDS © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

3.8 Fats are lipids that are mostly energy- storage molecules Lipids differ from carbohydrates, proteins, and nucleic acids in that they are not huge molecules and not built from monomers. Lipids vary a great deal in structure and function. © 2015 Pearson Education, Inc.

3.8 Fats are lipids that are mostly energy- storage molecules We will consider three types of lipids: 1.fats, 2.phospholipids, and 3.steroids. A fat is a large lipid made from two kinds of smaller molecules: glycerol and fatty acids. © 2015 Pearson Education, Inc.

3.8 Fats are lipids that are mostly energy- storage molecules A fatty acid can link to glycerol by a dehydration reaction. A fat contains one glycerol linked to three fatty acids. Fats are often called triglycerides because of their structure. © 2015 Pearson Education, Inc.

Animation: Fats © 2015 Pearson Education, Inc.

Figure 3.8a Glycerol Fatty acid H2OH2O What is it called when water is removed from something?

© 2015 Pearson Education, Inc. Figure 3.8b

© 2015 Pearson Education, Inc. Figure 3.8c-0 Saturated fatsUnsaturated fats

3.8 Fats are lipids that are mostly energy- storage molecules Some fatty acids contain one or more double bonds, forming unsaturated fatty acids. These have one fewer hydrogen atom on each carbon of the double bond. These double bonds cause kinks or bends in the carbon chain, preventing them from packing together tightly and solidifying at room temperature. Fats with the maximum number of hydrogens are called saturated fatty acids. © 2015 Pearson Education, Inc.

3.8 Fats are lipids that are mostly energy- storage molecules Unsaturated fats are referred to as oils. Most animal fats are saturated fats. Hydrogenated vegetable oils are unsaturated fats that have been converted to saturated fats by adding hydrogen. This hydrogenation creates trans fats (aka partially hydrogenated), which are associated with health risks © 2015 Pearson Education, Inc.

3.10 Phospholipids and steroids are important lipids with a variety of functions Phospholipids are the major component of all cell membranes. Phospholipids are structurally similar to fats. Fats contain three fatty acids attached to glycerol. Phospholipids contain two fatty acids attached to glycerol. © 2015 Pearson Education, Inc.

Figure 3.10 Phosphate group Glycerol Hydrophilic heads Hydrophobic tails Symbol for phospholipid Water

3.10 Phospholipids and steroids are important lipids with a variety of functions Phospholipids cluster into a bilayer of phospholipids. The hydrophilic heads are in contact with the water of the environment and the internal part of the cell. The hydrophobic tails cluster together in the center of the bilayer. © 2015 Pearson Education, Inc.

3.10 Phospholipids and steroids are important lipids with a variety of functions Steroids are lipids in which the carbon skeleton contains four fused rings. Cholesterol is a common component in animal cell membranes and a starting material for making steroids, including sex hormones. © 2015 Pearson Education, Inc.

Figure 3.10c

3.11 CONNECTION: Anabolic steroids pose health risks Anabolic steroids are synthetic variants of the male hormone testosterone that are abused by some athletes with serious consequences, including violent mood swings, depression, liver damage, cancer, high cholesterol, and high blood pressure. © 2015 Pearson Education, Inc.