Identifying and Classifying Bacteria Ch. 23

What is a prokaryote? Cells that lack a true nucleus. Cells that lack a true nucleus. Cells that lack membrane- bound organelles. Cells that lack membrane- bound organelles. Most surrounded by a cell wall. Most surrounded by a cell wall. Many secrete a protective slime capsule. Many secrete a protective slime capsule.

How big is a prokaryotic cell? 1- 5 micrometers 1- 5 micrometers (1 millionth of a meter) (1 millionth of a meter)

Classification Archaebacteria vs Eubacteria Archaebacteria vs Eubacteria

Archaebacteria Surrounded by a cell wall lacking peptidoglycan. Surrounded by a cell wall lacking peptidoglycan. Live in extreme conditions Live in extreme conditions

Examples of Archae Methanogens: convert H 2 and CO 2 into methane gas for energy Methanogens: convert H 2 and CO 2 into methane gas for energy Halophiles: love salt Halophiles: love salt Thermoacidophiles: love heat and acid Thermoacidophiles: love heat and acid

Eubacteria: Surrounded by a cell wall made of peptidoglycan. Surrounded by a cell wall made of peptidoglycan. Example: rhizobium- nitrogen–fixing bacteria Example: rhizobium- nitrogen–fixing bacteria

Identifying Prokaryotes 1. Shape: Coccus – spherical Coccus – spherical Bacillus – rod-shaped Bacillus – rod-shaped Spirillum – spiral Spirillum – spiral Vibrio – comma shape Vibrio – comma shape

Coccus Spirillum Vibrio Bacillus

Ex. Diplococcus Cocci and Bacilli may group together Prefixes for arrangements: Diplo – two

Strepto – chain Streptococcus Streptobacillus

Staphylo - clustered Staphylococcus

2. Motility: ability to move Flagella: whip-like structure used to propel bacteria Flagella: whip-like structure used to propel bacteria Slime: glide along slime secretion Slime: glide along slime secretion Spiral motion: cork-screw motion (spirillum) Spiral motion: cork-screw motion (spirillum)

3. Metabolism: Oxygen or NOT Obligate Aerobes: Need oxygen Obligate Aerobes: Need oxygen Obligate Anaerobes: cannot live in oxygen Obligate Anaerobes: cannot live in oxygen Facultative anaerobes: can live with or without oxygen Facultative anaerobes: can live with or without oxygen

3.Metabolism: Obtaining Energy Autotroph vs. Heterotroph Photoautotroph- uses light energy for photosynthesis Photoautotroph- uses light energy for photosynthesis Chemoautotroph- uses energy from inorganic chemicals for chemosynthesis Chemoautotroph- uses energy from inorganic chemicals for chemosynthesis

Photoheterotrophs- uses photosynthesis and eats organic compounds Photoheterotrophs- uses photosynthesis and eats organic compounds Heterotroph – consumes organic compounds Heterotroph – consumes organic compounds

review What role do chemosynthetic bacteria have in the ecosystem? What role do chemosynthetic bacteria have in the ecosystem? BzClAc&NR=1 BzClAc&NR=1 BzClAc&NR=1 BzClAc&NR=1

Bacterial Reproduction

Asexual: Binary fission 1. Circular DNA replicates 2. Cell membrane and cell wall divide 3. Identical daughter cells separate

How fast does this happen? /watch?v=gEwzDydciWc &feature=related /watch?v=gEwzDydciWc &feature=related /watch?v=gEwzDydciWc &feature=related /watch?v=gEwzDydciWc &feature=related approximately every 20 minutes approximately every 20 minutes

Genetic recombination Sharing or exchanging of genetic material 3 types: 1. Conjugation 2. Transformation 3. Transduction

1. Conjugation A temporary bridge forms between two cells. A temporary bridge forms between two cells. A plasmid, a separate section of DNA, is transferred from one cell to the other. A plasmid, a separate section of DNA, is transferred from one cell to the other. Often the plasmid contains useful genes, like antibiotic resistance. Often the plasmid contains useful genes, like antibiotic resistance.

2. Transformation Bacteria takes in DNA from the environment. Bacteria takes in DNA from the environment. Dead bacteria may break apart and release DNA. Dead bacteria may break apart and release DNA. Other bacteria can pick up this DNA and become genetically different. Other bacteria can pick up this DNA and become genetically different.

3. Transduction Viruses can pick up small amounts of DNA from a host bacteria. Viruses can pick up small amounts of DNA from a host bacteria. When it infects another bacteria, the new DNA is transferred into that cell. When it infects another bacteria, the new DNA is transferred into that cell.

Disease Pathology is the study of disease. Pathology is the study of disease. Pathogens: organisms that cause disease. Pathogens: organisms that cause disease.

Gram-staining Test Gram-positive: bacteria contain lots of peptidoglycan in cell walls. Stains purple. Gram-positive: bacteria contain lots of peptidoglycan in cell walls. Stains purple. Gram- negative: bacteria contain little peptidoglycan in cell walls. Stains red. Gram- negative: bacteria contain little peptidoglycan in cell walls. Stains red.

Exotoxins Poisonous proteins that are released by some gram- positive bacteria. Poisonous proteins that are released by some gram- positive bacteria.

For example Clostridium tetani secretes an exotoxin that causes tetanus. Clostridium tetani secretes an exotoxin that causes tetanus. Tetanus causes stiffness in muscles. Tetanus causes stiffness in muscles. Clostridium botulinum produces a very powerful exotoxin that causes the fatal disease, botulism. Clostridium botulinum produces a very powerful exotoxin that causes the fatal disease, botulism. 1 g of botulism toxin can kill 1 million people. 1 g of botulism toxin can kill 1 million people.

Endotoxins Lipids and carbohydrates in the cell membranes of some Gram-negative bacteria, that are poisonous. Lipids and carbohydrates in the cell membranes of some Gram-negative bacteria, that are poisonous. They are released when the bacteria die. They are released when the bacteria die.

For example: Most species of Salmonella, are endotoxin producing bacteria. Most species of Salmonella, are endotoxin producing bacteria. Salmonella typhi, causes typhoid fever. Salmonella typhi, causes typhoid fever.

Antibiotics Antibiotics interfere with the bacteria’s cellular activities. Antibiotics interfere with the bacteria’s cellular activities.

For example: Penicillin: blocks the building of the cell wall. Penicillin: blocks the building of the cell wall. “Accidently” discovered by Alexander Fleming in 1920s Tetracyline: blocks protein synthesis. Tetracyline: blocks protein synthesis.

Where do antibiotics come from? Antibiotics are naturally made by some fungi and bacteria. Antibiotics are naturally made by some fungi and bacteria. Some are made synthetically in labs. Some are made synthetically in labs. But most used in treatment still come from bacteria. But most used in treatment still come from bacteria.

Antibiotic-Resistance Bacteria can quickly adapt to their environment because of their rapid rate of reproduction. Bacteria can quickly adapt to their environment because of their rapid rate of reproduction.

Antibiotic-Resistance 1. If one bacterium mutates and becomes resistant, 2. then in the presence of antibiotics, bacteria not resistant die 3. Those with the resistance take over the population.

Which diseases are preventable by better sanitation practice? Cholera Cholera Salmonella Salmonella Tetanus Tetanus Staph Staph

What are other ways that antibiotic resistance is passed? Genetic recombination Genetic recombination