Chapter 12.1 The Prokaryotes: Kingdom Archae and Bacteria

What are Bacteria? “Bacteria” - describes organisms that belong to Kingdom Archaebacteria and Eubacteria. singular - bacterium Kingdom Archaebacteria Oldest group of organisms on Earth live only in extreme environments Kingdom Eubacteria typically think of as “true bacteria”

Structure of Bacteria DNA Plasmid Cell Wall 1 single chromosome Contains the genetic information Plasmid Smaller ring of DNA containing fewer genes than chromosome Cell Wall -Provides structure and protection Flagella (singular: flagellum) - Whiplike structure for MOVEMENT -stems from cell wall and cell membrane

Prokaryotes vs. Eukaryotes DNA floats freely in cytoplasm No nucleus No membrane-bound organelles Eukaryotes: DNA enclosed in nucleus Membrane-bound organelles present For example: chloroplast, mitochondria 10 times larger in size compared to prokaryotes

Bacteria Characteristics: Live almost EVERYWHERE! Microscopic – vary between 1-10μm Single-celled organisms = unicellular All bacteria are prokaryotes: DNA is not contained in a nucleus and do not have membrane-bound cell organelles DNA is made up of 1 single chromosome in the shape of a ring All bacteria reproduce asexually by binary fission

Bacteria Diversity Bacteria show incredible diversity. Because of this diversity, they are classified and grouped according to: Shape Reaction to gram stain Nutrition Respiration

Cell Shape Coccus (plural cocci) – spherical Think C – circle Bacillus (plural bacilli) – rod-shaped Think B – bat Spirillum (plural spirilli) – spiral-shaped Think S - spiral

Cocci (sphere) Bacillus (rod shaped) Spirillum (spiral shaped)

Combinations of Bacteria Shapes

Gram Staining Gram stain is a dye made of crystal violet and iodine Bacteria are classified according to their reaction with gram stain. Gram-positive bacteria Appear purple because they retain crystal violet Gram-negative bacteria Appear light pink because do not retain crystal violet Pathogenic (causing harm) Gram positive and negative bacteria react differently because they have different cell wall compositions

Gram Positive and Gram Negative Bacteria

Nutrition Nutrition - obtaining or creating organic compounds required for cellular metabolism 1.) source of energy 2.) source of carbon compounds Autotrophs – make their own organic compounds. For example: synthesize glucose from carbon dioxide Heterotrophs – obtain carbon from their environment and break it down to create organic compounds

Nutritional Patterns of Bacteria Mode of Nutrition Energy Source Carbon source Autotrophs Photoautotroph Light CO2 Chemoautotroph Inorganic chemicals (sulfur, nitrogen) Heterotrophs Photoheterotroph Organic compounds Chemoheterotroph Tips to remember: “photo” means light Autotrophs – obtain carbon in the form of CO2 to synthesize organic compounds Heterotrophs – obtain carbon from organic compounds.

Cyanobacteria - Photoautotroph “blue-green” bacteria Undergoes photosynthesis by using CO2 and sunlight to create organic compounds Does not contain chloroplast Cyanobacterial bloom – rapid population increase of cyanobacteria. Indicator of water pollution due to nitrates, and phosphates. Lichen – cyanobacteria lives symbiotically (together) with fungi

Characteristics of Heterotrophs Review: Where do heterotrophs obtain source of carbon? Parasites – absorb nutrients from living host organisms Saprobes – absorb nutrients from decomposing, dead organic matter

Respiration Recall: What is cellular respiration? Cellular respiration – breakdown of organic carbon compounds for energy Bacteria carry out respiration on inner surface of cell membrane (vs. eukaryotes carry out respiration in mitochondria) Aerobes – bacteria use oxygen to undergo cellular respiration Obligate aerobes – absolutely require oxygen for survival and cellular respiration. “Obligated” to use oxygen.

Respiration Cont’d Anaerobe – bacteria that carry out cellular respiration in oxygen-free environment Obligate anaerobe – presence of oxygen kills the bacteria. “Obligated” to not use oxygen. Facultative anaerobe – can survive with or without oxygen.

Reproduction Bacteria reproduce asexually through a process called binary fission Binary fission – parent cell divides into 2 identical offspring cells Most bacteria can divide every 15 minutes as long as there is enough food, warmth and space Growth of bacteria is exponential Question: If bacteria can grow exponentially, then why is Earth not covered with a massive layer of bacteria?

Binary Fission Steps in Binary Fission: Circular chromosome attaches to plasma membrane 2. Chromosome replicates and daughter chromosomes attach to different sites on plasma membrane. Plasmid also replicates with single chromosome. 3. Cell continues to grow. 4. Cell wall and membrane join together. END RESULT: 2 identical daughter cells

Binary Fission – Cont’d Watch: http://www.youtube.com/watch?v=gEwzDyd ciWc&feature=related Question: After having studied genetics, you know that mutations are rare. If the DNA of 1 bacterium were to contain a mutation, would this have an effect on the population? Answer: Yes, because they reproduce rapidly through binary fission.

Conjugation Conjugation – type of sexual reproduction that bacteria undergo during difficult conditions and limited sources. Conjugation Process – bacteria connect with a long protein bridge and transfer plasmid of one bacterium to another. Result: Bacteria now have different genetic material Question: How might a different genetic makeup help the bacteria? Answer: Help bacteria survive difficult environmental conditions. New genes may help bacteria to adapt to the changing conditions.

Conjugation & Antibiotic Resistance Bacteria that are resistant contain the R-plasmid R-plasmid contains genes that code for enzymes that destroy specific types of antibiotics. Constant competition between pathogens and scientists who develop antibiotics Question: A bacterial population consists of bacteria that have the R-plasmid and others that do not. What will happen to the 2 different bacteria when antibiotic treatment is applied? Answer: R-plasmid bacteria survive and can pass R-plasmid via congujation. Bacteria without R-plasmid will die.

Endospore Formation Bacteria form endospores when growing conditions are extremely unfavourable Endospore – thick wall that surrounds DNA and cytoplasm Endospore remains dormant until conditions are favourable for growth Endospore of Bacillus sp.

Kingdom Archaebacteria Oldest group of organisms on Earth Live in extremely harsh environments similar to the conditions present billions of years ago on Earth. Examples: extremely salty, acidic, hot. Groups of Archaebacteria Anaerobic methanogen - live in oxygen-free places and produce methane gas. Example: guts of herbivores Halophiles – “salt-loving” organisms that live in salty lakes. Example: Dead Sea Thermophiles - live in hot, acidic environments. Example: hot springs.

Kingdom Eubacteria Contains majority of the prokaryotes on Earth Known as “true bacteria” Cell wall and cell membrane different from Archaebacteria Genetically different from Archaebacteria More than 50% of the genes are different Examples: Gram positive bacteria Cyanobacteria

Bacteria & The Ecosystem Nitrogen-fixing bacteria – live freely in the soil or within the root nodules of plants. They convert nitrogen in the air into nitrates for plants to use Other bacteria feed on decomposing, dead material. They release carbon dioxide back into the atmosphere.

Bacteria & Disease Pathogens – bacteria that cause diseases by producing toxins. Toxins – deadly substances that are released into the body and cause symptoms 2 types of toxins: Endotoxins – fatal toxins that are released when gram- negative bacteria split. Normally cause fever, vomiting and diarrhea. Salmonella and Echerichia produce endotoxins Exotoxins – highly toxic molecules released when bacteria multiply. Examples of endotoxin diseases: tetanus and botulism

Other Applications of Bacteria Waste Management Bacteria are used to eliminate or neutralize toxic compounds in the environment Sewage Treatment Bacteria decompose waste and recycle organic matter. Commonly used to decompose human fecal waste. Dairy Foods Lactic acid bacteria are used in the production of dairy foods Question: Are bacteria used in any other ways?