The Prokaryotes Archaea & Eubacteria PDF

The Prokaryotes: Archaea & Eubacteria SBI3U(G) Domain Archaea Contains only the Kingdom Archaea Characteristics: ◦ Differ from eubacteria in that their cell membrane and cell wall LACK peptidoglycan ◦ Specialized enzymes not denatured by the environment ◦ Inhabit extreme...

The Prokaryotes: Archaea & Eubacteria SBI3U(G) Domain Archaea Contains only the Kingdom Archaea Characteristics: ◦ Differ from eubacteria in that their cell membrane and cell wall LACK peptidoglycan ◦ Specialized enzymes not denatured by the environment ◦ Inhabit extreme environments Three branches Archaea and Viruses  Important Groups to Know Euryarchaeota subgroup Key Features Methanogens live in low oxygen environments (sediments, digestive tracts of mammals, etc) Generate energy by converting chemical compounds into methane gas, which is released into the atmosphere Halophiles live in highly saline environments Aerobic (need oxygen for cellular respiration) Some use light as secondary energy source Extreme thermophiles Live in extremely hot environments (hot springs, hydrothermal vents) Optimal temperature for growth is 70°C to 95°C Psychrophiles Cold loving (live in Arctic oceans and cold ocean depths) Optimal temperature for growth is -10°C to -20°C Some Archaea Environments 1. Methanogenic Archaea – in the rumen of herbivores 2. Halophiles in areas of high salt concentration 3. & 4. Thermoacidophiles love geysers and deep sea vents Domain Eubacteria Contains only the Kingdom Eubacteria Intro to Bacteria Sometimes referred to as just “Bacteria” ◦ Eubacteria means “true bacteria” Twelve branches (only six groups shown) Important Groups to Know Important Groups to Know Group Key Features Proteobacteria Ancestors of mitochondria Some photosynthetic (different from plants), some nitrogen fixing Responsible for many diseases (bubonic plague, gonorrhea, dysentery, and some ulcers) Cyanobacteria Ancestors of chloroplasts Photosynthetic Gram-positive bacteria Commonly seen as both helpful (food production) and harmful bacteria (diseases) Gram Staining… Gram + simple cell walls large amounts of peptidoglycan these stain purple Gram - complex cell walls smaller amounts of peptidoglycan also possess an outer lipid containing membrane these don’t hold the purple stain well  Gram Negative Bacteria more dangerous as disease organisms – outer membrane is often hidden by a capsule or slime layer hides the antigens of the cell and so acts as "camouflage" More resistant to antibiotics (more able to develop resistance)  Gram Positive Bacteria infections are generally less severe human body does not contain peptidoglycan and produces an enzyme which attacks the peptidoglycan layer of Gram-positive bacteria frequently much more susceptible to common antibiotics, such as penicillin Characteristics of Eubacteria PART Description and Function Small hair-like structures made of stiff Pili proteins that help bacteria adhere to other cells and surfaces Flagellum Whip-like tails used to propel bacteria Sticky material surrounding cell to reduce water Capsule loss, resist high temp. and block antibiotics and viruses plasmid Mostly composed of peptidoglycan to create Cell Wall rigid, protective cell wall Plasma membrane, forms a barrier between Cell Memb. the cell and its environment, allows selective movement of material in and out Chromoso Single loop of genetic information (DNA) necessary for vital cell function, found in me region called nucleoid Very small loop of DNA, can carry genes that Plasmid provide resistance to antibiotics Bead-like structures that translates the Ribosome information from DNA to make proteins Cytoplasm Fluid-filled space within the cell membrane Bacteria can be classified by their shape: Shape Single (plural) Pairs Chain Clusters Coccus (cocci) Streptococcus Staphylococcus Diplococcus Round Bacillus (bacilli) Diplobacillus Streptobacillus Rod Spirillum (spirilli) Spiral Why are bacteria so successful? 1. Diversity in Metabolism Some are autotrophic ◦ Produce organic (complex carbon based) molecules from simple inorganic molecules ◦ Energy from carbon dioxide, water, minerals, hydrogen, sulfur, iron Most are heterotrophic ◦ Use organic molecules formed by other organisms (bacteria that obtain carbon from dead organisms are called saprotrophs) ◦ Energy from sugars, fats, and proteins  Why are bacteria so successful? 2. Can live with or without oxygen Obligate aerobes : ◦ need oxygen for cellular respiration (the process of getting energy from food) Facultative aerobe: ◦ can live with or without oxygen ◦ Oxygen present 🡪 aerobic respiration ◦ Oxygen absent🡪 anaerobic fermentation Obligate anaerobe: ◦ Cannot live in the presence of oxygen  Why are bacteria so successful? 3. They occupy every ecological niche Producers: ◦ Source of food for other organisms Decomposers: ◦ Break down dead or decaying organisms Can form symbiotic relationships ◦ Mutualism (benefits both) ◦ Commensalism (one benefits, doesn’t affect other) ◦ Parasitism (one benefits, one affected negatively)  Why are bacteria so successful? 4. Some Genera (eg. Genus Clostridium, genus Bacillus) can form protective encasements called endospores Forms around the chromosome when the cell is under stress Remaining cellular components fall away Small dormant endospore that can withstand extreme environments for long periods of time Endospores  Reproduction in Bacteria 1. Asexual reproduction – by Binary Fission ◦ One parent cell divides into two genetically identical daughter cells 1. Chromosome and plasmid replicate 2. Cell elongates 3. Septum or wall forms to divide the cell 4. Cytokinesis ◦ Errors in DNA replication create mutations (provides genetic diversity)  Reproduction in Bacteria 2. Sexual Reproduction DNA is exchanged between two individuals a) Conjugation ◦ Two cells share genetic information when one cell copies genetic information from one plasmid and transfers it to a second cell ◦ The DNA is transferred through connecting pili.  Reproduction in Bacteria b) Transformation ◦ A whole strand of DNA (or fragments of DNA) are transferred from a dead bacteria to a living one from the environment. ◦ Physical contact is not required ◦ Also called horizontal gene transfer (if DNA is not from the same species). ◦ Newly “transformed” bacteria can now perform functions of the dead bacteria Example: could now become pathogenic (disease-causing) or resistant to certain antibiotics ◦ DNA does not have to be from the same species ◦ How antibiotic resistance spreads between bacteria Bacterial Reproduction: Impacts on Antibiotic Resistance By reproducing quickly and thus accumulate mutations and by their ability to swap and gain new DNA, bacteria can change rapidly A change in characteristics can be good, bad or neutral Often leads to a difference in response to antibiotics E. coli developing resistance video Antibiotics How antibiotics work Antibiotics impact living pathogens and so are not effective with viral infections. ◦ Exposing our ‘good bacteria’ to antibiotics when unnecessary is bad for us ◦ Exposing any bacteria population to antibiotics strengthens it as a whole. (weakest are killed off and resistant left to reproduce) How to take antibiotics If a patient stops taking their antibiotis early because they feel better, what can be happening? ◦ Some resistant bacteria can be left to develop a resistant population ◦ It is super important to take a full prescription to ensure the entire pathogen population is destroyed. Bacillus anthracis spores in lung bronchiole E. coli on the surface of the small intestine Staphylococcus aureus on the surface of human skin and hair follicle Importance of Bacteria to Your Health TED Talk: You and your 100 trillion friends... TED Talk: How Our Microbes Makes Us Who We Are TED Talk: We're Covered in Germs. Let's Design for That