MicrobiologyAN INTRODUCTION

EIGHTH EDITION

TORTORA • FUNKE • CASE

Chapter 2, part B

Chemical Principles

Important Biological Molecules

• Organic compounds always contain carbon and hydrogen.

• Inorganic compounds typically lack carbon.

• Polar molecule

Inorganic Compounds: Water

Figure 2.4a

• Solvent– Polar

substances dissociate, forming solutes

Inorganic Compounds: Water

Figure 2.5

• H+ and OH participate in chemical reactions

Inorganic Compounds: Water

• Hydrogen bonding between water molecules makes water a temperature buffer.

Inorganic Compounds: Water

Figure 2.4b

• An acid is a substance that dissociates into one or more H+.

HCl H+ + Cl

Acids, Bases, and Salts

Figure 2.6a

• A base is a substance that dissociates into one or more OH.

NaOH Na+ +

OH

Acids, Bases, and Salts

Figure 2.6b

• A salt is a substance that dissociates into cations and anions, neither of which is H+ or OH.

NaCl Na+ + Cl

Acids, Bases, and Salts

Figure 2.6c

• The amount of H+ in a solution is expressed as pH.

• pH = log[H+]

• Increasing [H+], increases acidity.

• Increasing [OH] increases alkalinity.

• Most organisms grow best between pH 6.5 and 8.5.

Acid-Base Balance

Acid-Base Balance

Figure 2.7

• The chain of carbon atoms in an organic molecule is the carbon skeleton.

• Functional groups are responsible for most of the chemical properties of a particular organic compound.

Organic Compounds

Table 2.3.1

• Small organic molecules can combine into large macromolecules.

• Macromolecules are polymers consisting of many small repeating molecules.

• The smaller molecules are called monomers.

Organic Compounds

• Monomers join by dehydration synthesis or condensation reactions.

Organic Compounds

Figure 2.8

• Are important for structure and as energy sources.

• Also for structures like cell walls

• Consist of C, H, and O with the formula (CH2O)n

Carbohydrates

Figure 2.8

• Monosaccharides are simple sugars with 3 to 7 carbon atoms.

Carbohydrates

Figure 2.8

• Disaccharides are formed when two monosaccharides are joined in a dehydration synthesis.

• Disaccharides can be broken down by hydrolysis.

Carbohydrates

Figure 2.8

• Oligosaccharides consist of 2 to 20 monosaccharides.

• Polysaccharides consist of tens or hundreds of monosaccharides joined through dehydration synthesis.

• Starch, glycogen, dextran, and cellulose are polymers of glucose that are covalently bonded differently.

• Chitin is a polymer of two sugars repeating many times. What is Chitin?

Carbohydrates

• Three types of lipids:– Simple fats also known as triglycerides– Phospholipids– Steroids

• Are the primary components of cell membranes.• Function as storage of energy, membrane

structure and some act as hormones (steroids).• Consist of C, H, and O.• Are nonpolar and insoluble in water.

Lipids

• Called fats or triglycerides contain glycerol and fatty acids; formed by dehydration synthesis.

• Unsaturated fats have one or more double bonds in the fatty acids.

Simple lipids

Figure 2.9c

• Contain C, H, and O + P, N, or S.

• Membranes are made of phospholipids

Phospholipids lipids

Figure 2.10a

• Consist of four carbon rings, with an –OH group attached to one ring.

• Are part of membranes.

Steroids

Figure 2.11

• Are essential in cell structure and function as enzymes.

• Enzymes are proteins that speed chemical reactions.

• Transporter proteins move chemicals across membranes.

• Flagella are made of proteins.

• Some bacterial toxins are proteins.

Proteins

• Consist of monomer subunits called amino acids.

Proteins

Table 2.4.1

Proteins

Table 2.4.2

• Exist in either of two stereoisomers, D or L.

• L-forms are most often found in nature.

Amino Acids

Figure 2.13

• Peptide bonds between amino acids are formed by dehydration synthesis.

Peptide Bonds

Figure 2.14

• The primary structure is a polypeptide chain

Levels of Protein Structure

Figure 2.15a

• The secondary structure occurs when the amino acid chain folds and coils in a regular helix or pleats.

Levels of Protein Structure

Figure 2.15b

• The tertiary structure occurs when the helix folds irregularly, forming disulfide bonds, hydrogen bonds, and ionic bonds between amino acids in the chain.

Levels of Protein Structure

Figure 2.15c

• The quaternary structure consists of two or more polypeptides.

Levels of Protein Structure

Figure 2.15d

• Conjugated proteins consist of amino acids and other organic molecules:• Glycoproteins• Nucleoproteins• Lipoproteins

Level of Protein Structure

• Consist of monomer units called nucleotides.

• Nucleotides consist of a:• Pentose• Phosphate group• Nitrogen-containing (purine or pyrimidine) base

• Adenine, thymine, guanine or cytosine

Nucleic Acids

Figure 2.16

• Has the sugar deoxyribose

• Exists as a double helix with sugar and phosphate as backbone

• A hydrogen bonds with T

• C hydrogen bonds with G

DNA

Figure 2.16

• Has sugar ribose• Is single-stranded• A hydrogen

bonds with U

• C hydrogen bonds with G

RNA

Figure 2.17

• Has ribose, adenine, and 3 phosphate groups

ATP

Figure 2.18

• Is made by dehydration synthesis.

• Is broken by hydrolysis to liberate useful energy for the cell.

ATP