Lecture 3THE CHEMISTRY OF LIVING

THINGS

Table 2.1

III. Atoms Combine to Form Molecules

C. Three types of BondsC. Three types of Bonds

Figure 2.6

III. Atoms Combine to Form Molecules

Covalent BondCovalent Bond

Covalent Bonds

Figure 2.7

III. Atoms Combine to Form Molecules

Ionic BondIonic Bond

Ionic Bonds

Hydrogen Bonds

IV. Elements of Living Organisms

Table 2.2

A. Water molecules are polarA. Water molecules are polar

B. Water is liquid at body temperatureB. Water is liquid at body temperature

C. Water can absorb & hold heat energyC. Water can absorb & hold heat energy

V. Life Depends on Water

D. Two Important Biological Functions D. Two Important Biological Functions of Waterof Water

1. Water is the biological Solvent1. Water is the biological Solvent

2. Water helps regulate body temperature2. Water helps regulate body temperature

V. Life Depends on Water

Water Keeps Ions in Solution

Figure 2.9

A. Acids are proton (hydrogen ion) donors, A. Acids are proton (hydrogen ion) donors,

1. Bases accept hydrogen ions1. Bases accept hydrogen ions

B. pH Scale = hydrogen ion concentrationB. pH Scale = hydrogen ion concentration

C. Buffers: minimize pH changeC. Buffers: minimize pH change

1. Carbonic acid & bicarbonate act as one of 1. Carbonic acid & bicarbonate act as one of body’s most important buffer pairsbody’s most important buffer pairs

VI. The Importance of Hydrogen Ions

The pH Scale

Figure 2.11

A. Carbon, the building block of living things:A. Carbon, the building block of living things:

1. Comprises 18% of body by weight1. Comprises 18% of body by weight

2. Forms four covalent bonds2. Forms four covalent bonds

3. Can form single or double bonds3. Can form single or double bonds

4. Can build micro- or macromolecules4. Can build micro- or macromolecules

VII. The Organic Molecules of Living Organisms

Carbon Can Bond in Many Ways

Figure 2.13

VIII. Making & Breaking Biological Macromolecules

Figure 2.14

A. Dehydration synthesisA. Dehydration synthesis

1. Removes equivalent of a water molecule to 1. Removes equivalent of a water molecule to link molecular unitslink molecular units

2. Requires energy2. Requires energy

B. HydrolysisB. Hydrolysis

1. Adds the equivalent of a water molecule to 1. Adds the equivalent of a water molecule to break apart macromoleculesbreak apart macromolecules

2. Releases energy2. Releases energy

VIII. Making & Breaking Biological Macromolecules

IX. Carbohydrates

Figure 2.15

A. Oligosaccharides: short chains of A. Oligosaccharides: short chains of monosaccharidesmonosaccharides

Disaccharides: sucrose, maltose, lactoseDisaccharides: sucrose, maltose, lactose

IX. Carbohydrates

B. Polysaccharides: thousands of B. Polysaccharides: thousands of monosaccarides joined in chains & branchesmonosaccarides joined in chains & branches

1. Starch: made in plants; stores energy1. Starch: made in plants; stores energy

2. Glycogen: made in animals; stores energy2. Glycogen: made in animals; stores energy

3. Cellulose: undigestible polysaccharide made in 3. Cellulose: undigestible polysaccharide made in plants for structural supportplants for structural support

IX. Carbohydrates

A. Triglycerides: energy storage moleculesA. Triglycerides: energy storage molecules

Ex: Fatty acids: saturated and unsaturatedEx: Fatty acids: saturated and unsaturated

B. Phospholipids: cell membranesB. Phospholipids: cell membranes

C. Steroids: carbon-based ring structuresC. Steroids: carbon-based ring structures

Ex: Cholesterol: used in making estrogen and Ex: Cholesterol: used in making estrogen and testosteronetestosterone

X. Lipids: Insoluble in Water

Triglycerides

Figure 2.17

Phospholipids & Steroids

Figure 2.18

Figure 2.19

Protein Structure

Figure 2.18

A. StructureA. Structure

1. Primary: amino acid sequence1. Primary: amino acid sequence

2. Secondary: describes chain’s orientation in 2. Secondary: describes chain’s orientation in space; e.g., alpha helix, beta sheetspace; e.g., alpha helix, beta sheet

XI. Proteins: Complex Structures Constructed of Amino Acids

A. StructureA. Structure

3. Tertiary: describes three-dimensional 3. Tertiary: describes three-dimensional shape created by disulfide and hydrogen shape created by disulfide and hydrogen bondsbonds

Creates polar and nonpolar areas in moleculeCreates polar and nonpolar areas in molecule

4. Quaternary: describes proteins in which 4. Quaternary: describes proteins in which two or more tertiary protein chains are two or more tertiary protein chains are associatedassociated

XI. Proteins: Complex Structures Constructed of Amino Acids

Protein Structure

Figure 2.18

XI. Proteins: Complex Structures Constructed of Amino Acids

A. Enzymes:A. Enzymes:

1. proteins1. proteins

2. function as catalysts2. function as catalysts

3 facilitate chemical reactions3 facilitate chemical reactions

B. B. The functional shape of an enzyme is The functional shape of an enzyme is dependent on:dependent on:

1. temperature of reaction medium 1. temperature of reaction medium

2. pH 2. pH

3. ion concentration3. ion concentration

4. presence of inhibitors4. presence of inhibitors

XII. Enzyme Function

A. FunctionsA. Functions

1. Store genetic information1. Store genetic information

2. Provide information used in making 2. Provide information used in making proteinsproteins

B. StructureB. Structure

1. Nucleotides consist of a phosphate group, a 1. Nucleotides consist of a phosphate group, a sugar, and a nitrogenous basesugar, and a nitrogenous base

2. DNA structure is a double helix: two 2. DNA structure is a double helix: two associated strands of nucleic acidsassociated strands of nucleic acids

3. RNA is a single-stranded molecule3. RNA is a single-stranded molecule

XII. Structure and Function of Nucleic Acids

C. DNA: double-strandedC. DNA: double-stranded

1. Sugar: deoxyribose1. Sugar: deoxyribose

2. Nitrogenous bases: adenine, thymine, 2. Nitrogenous bases: adenine, thymine, cytosine, guaninecytosine, guanine

3. Pairing: adenine-thymine and cytosine-3. Pairing: adenine-thymine and cytosine-guanineguanine

XII. Structure and Function of Nucleic Acids

D. RNA: single-strandedD. RNA: single-stranded

1. Sugar: ribose1. Sugar: ribose

2. Nitrogenous bases: adenine, uracil, 2. Nitrogenous bases: adenine, uracil, cytosine, guaninecytosine, guanine

3. Pairing: adenine-uracil, cytosine-guanine3. Pairing: adenine-uracil, cytosine-guanine

XII. Structure and Function of Nucleic Acids

Structure and Function of Adenosine Triphosphate (ATP)

Figure 2.26