Bacteria on the Point of a Pin

Usually small (< 5 m) compared PROKARYOTES: Usually small (< 5 m) compared to most eukaryotic cells (10-100 m) Cell shapes: bacilli, cocci, spirilli; Some move by flagella (not 9+2), or by gliding

The Most Common Shapes of Prokaryotes

The Endospore of Clostridium tetani

This is the main reason why bacterial diseases such as Endospore This is the main reason why bacterial diseases such as Anthrax can last for decades.

REPRODUCTION: Can reproduce as quickly as every 20 minutes

Binary Fission Binary Fission

Prokaryote Colonies in Culture (on agar)

Prokaryote Evolutionary History Based on rRNA Gene Sequences: There are 2 prokaryotic domains: Bacteria & Archaea. The term “bacteria” is not a synonym for prokaryotes. Table 25.1

The Three Domains of Life

Domain Bacteria: About 5000 known species; most of the bacteria that “make the news” Lack organelles except ribosomes They are ubiquitous!

A Comparison of the Three Domains of Life

Evolved 3.5 bya – first cells on earth! Domain Archaea: methanogens produce methane in deep sea thermal vents & freshwater sediments halophiles occupy very saline waters(Dead Sea, Great Salt Lake) thermophiles live in very hot waters (to 113ºC) (e.g. Yellowstone thermal pools) Evolved 3.5 bya – first cells on earth!

“Heat-loving” Prokaryotes

Specialized Membranes of Prokaryotes Thylakoid Membranes Respiratory Membranes

DNA can also be absorbed from another cell--transformation, or transferred among prokaryotic cells by viruses--transduction

Some bacteria produce surface pili-- tubular structures that attach prokaryotic cells to host cells, or to each other during conjugation- DNA transfer can occur.

Pili

Prokaryotic Conjugation

Walls are formed of peptidoglycan (unlike Archaea). Domain Bacteria: Walls are formed of peptidoglycan (unlike Archaea). There are two major wall types: Gram negative Gram positive Streptococcus Escherichia coli

Gram negative bacteria also have an outer lipid membrane that allows loss of purple crystal violet stain by washing. Cells can then be stained with a pink dye. Outer membrane can confer toxicity & antibiotic resistance.

Gram Negative: Stains pink or red

Gram positive bacteria have more peptidoglycan and lack outer lipid membrane; retain violet stain--appear purple Gram positive bacteria are more susceptible to antibiotics (e.g. penicillin) that interfere with peptidoglycan wall development.

Gram Positive: Stains violet/blue

1. Autotrophs generate their own reduced, energy-rich organics from carbon dioxide, methane, or other inorganics A. Photoautotrophs use light energy & fix CO2 via photosynthesis B. Chemoautotrophs oxidize inorganic compounds

2. Heterotrophs use reduced organic compounds produced by other organisms A. Photoheterotrophs use light energy to make ATP, but absorb organics B. Chemoheterotrophs obtain ATP by respiration or fermentation of organic molecules absorbed from environment. (fungi & animals, and some protists & plants also fall into this category)

Chemoheterotrophs that use secreted enzymes to break down dead organisms & organics are saprobes. (some fungi and protists & most animals are also saprobes) Chemoheterotrophs that absorb organics from living hosts are parasites (one way that bacteria cause disease).

Lyme disease, a Bacterial Disease (Borrelia burgdorferi) Transmitted by Ticks

Slowing Down Growth: Sterilization Radiation Freezing Refrigeration Using preservatives Pasteurization

Benefits of Bacteria: Production of Foods (cheese, breads, yogurt, pickles, sauerkraut) In industry they help produce antibiotics, dyes,vitamins,insecticides, cleaners, detergents

Benefits (continued) Major decomposer Coliform bacteria produce Vitamin K in our intestines Cyanobacteria are a major producer of oxygen in the atmosphere E. coli is used in biotech

4) The bacteria was cultured on this substance . . . 5) All of the multicellular protists are of this type. . 6) Red tides are caused by. . .