Methanogenesis Earth and Body Methanogens Methanogenesis Earth and Body

Bacteria Bacteria are prokaryotic cells 2 domains of bacteria: do not contain a nucleus 2 domains of bacteria: Archaeabacteria Bacteria There are two types of cell- prokaryotic and eukaryotic. Eukaryotic cells have a nucleus to hold the cell’s nuclear DNA. Organisms with these cells include the Kingdoms Fungi, Plantae, Animalia, and Protista (Many textbooks still say protists are in a Kingdom; however, they are now phyla). Prokaryotic cells do not have a nucleus to hold their DNA. Prokaryotic DNA is not membrane bound, rather is located in the cytoplasm of the cell. Prokaryotes include bacteria only. There are three domains: Eukarya (plants, animals, protists, fungi), Archaea, and Bacteria. We will concentrate on the Domain Archaea.

Domain Bacteria Have cell walls made of the carbohydrate peptidoglycan Live everywhere except harsh environments Can be pathogens Can be helpful to environment and humans by decomposing, cleaning oil spills, or making dairy products Just a little information to refresh our memory on the Domain Bacteria.

Domain Archaea Do have cell walls, but not made of peptidoglycan Are thought to be the first organisms to evolve on Earth Live in harsh environments only Really hot, cold, acidic, alkaline, or salty Such as undersea volcanic vents, very salty water, and digestive tracts Why are these organisms the first thought to evolve on Earth? They are able to live in harsh environments without oxygen. It is thought that the Earth did not have oxygen for some time.

Domain: Archaea Type of archaeabacteria: Methanogens- autotrophic, use anaerobic respiration to make ATP Cannot live in the presence of oxygen Carbon is reduced to produce methane as a product Examples: CO₂ + 4H₂ → CH₄ + 2H₂O C₃COOH → CH₄ + CO₂ There are many types of archaeabacteria, but we will focus on one type- methanogens because they make methane aka natural gas. Anaerobic respiration is the process of making chemical energy the cell can use, ATP, without oxygen.

Methanogens Found in the digestive tracts of animals, deep layers of marine sediment, hydrothermal vents, and wetlands. Responsible for some of the flatulence of animals even some humans Made in the rumen of the digestive tract

Methanogens Methanogens utilize the CO₂ and H₂ in the gut of some animals This will give CH₄ off as a product

Methanogens Methanogenesis- formation of methane by methanogens is the last step in the decay of organic matter in the Earth. As oxygen or other electron acceptors are depleted from the environment, carbon dioxide and hydrogen accumulate. This CO₂ is reduced by H₂ to form CH₄ as a product. Methanogenesis is responsible for a signification amount of natural gas in the Earth. You could discuss aerobic respiration and explain how oxygen is depleted and carbon dioxide is produced as a waste product.

Natural Gas The simplest hydrocarbon and the main component in natural gas. Natural gas is important for making electricity In doing this, produces less CO₂ and more energy per mass than other fossil fuels.

Exit Slip 1. What are methanogens? 2. What type of metabolic pathway do methanogens use to make ATP? 3. Where are methanogens found? 4. Create a Venn diagram to compare and contrast methanogenesis within the Earth and the body. Anaerobic, archaeabacteria that produce methane Anaerobic respiration Extreme environments where no oxygen is found such as marshes, digestive tracts of animals Similarities: same metabolic pathway is used to form methane Differences: Body- takes a relatively short amount of time to produce methane Earth- could take a very long time