Bacteria Prokaryotes - PDF

Chapter 2.2 The Prokaryotes: Comparing Kingdom Bacteria & Kingdom Archaea “Bacteria” - describes organisms that belong to either Kingdom Archaebacteria and Kingdom Eubacteria. singular - bacterium Kingdom Archaebacteria  Oldest group of organisms on Earth  Live in extremely harsh environment...

Chapter 2.2 The Prokaryotes: Comparing Kingdom Bacteria & Kingdom Archaea “Bacteria” - describes organisms that belong to either Kingdom Archaebacteria and Kingdom Eubacteria. singular - bacterium 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 Structure of Bacteria DNA -1 single chromosome -Contains the genetic information Plasmid -Smaller ring of DNA containing fewer genes than chromosome Cell Wall -Provides structure and Flagella (singular: protection flagellum) - Whiplike structure for MOVEMENT -stems from cell wall and cell membrane Prokaryotes vs. Eukaryotes Prokaryotes: -DNA floats freely in cytoplasm -No nucleus -No membrane-bound organelles Eukaryotes: -DNA enclosed in nucleus -Membrane-bound organelles present For example: chloroplast, mitochond -10 times larger in size compared to prokaryotes  Bacteria Characteristics: Bacteria 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: -Morphology (shape) -Aggregation (arrangement or groupings) -Reaction to gram stain (postive vs. negative) -Habitat (extremophiles vs. mesophiles) -Nutrition -Respiration Morphology (Cell Shape) Coccus (pl. cocci) sphere-shaped Bacillus (pl. bacilli) rod-shaped Spirillum (pl. spirilli) spiral- shaped Aggregation (Arrangement/grouping) Diplo - arranged in pairs Strepto –arranged in chains Staphylo –arranged in clusters Now let’s combine the two (shape and aggregation) and test your naming skills! How would you name this bacteria? Answer: Streptobacillus (Chains of rod-shaped bacillus) How would you name this bacteria? Answer: Staphylococcus (a cluster of sphere-shaped cells) Reaction to 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 and negative bacteria react differently because they have different cell wall compositions 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) Comparing 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  Comparing Nutritional Patterns of Bacteria (Autotrophs vs. heterotroughs) Mode of Nutrition Energy Source Carbon source Autotrophs Photoautotroph Light CO2 Chemoautotroph Inorganic chemicals CO2 (sulfur, nitrogen) Heterotrophs Photoheterotroph Light Organic compounds Chemoheterotroph Organic compounds Organic compounds Tips to remember: -“photo” means light -Autotrophs – obtain carbon in the form of CO 2 to synthesize organic compo -Heterotrophs – obtain carbon from organic compounds.  Photoautotroph (ex. Cyanobacteria)  Cyanobacteria is also known as “blue-green” bacteria (watch video)  Undergoes photosynthesis by using CO2 and sunlight to create organic compounds but do not contain chloroplasts  A Cyanobacterial bloom is a rapid population increase of cyanobacteria. It is an Indicator of water pollution due to increased nitrates and phosphates.  Lichen – cyanobacteria can also live symbiotically (together) with fungi as a composite organism! Characteristics of Heterotrophs Review: Where do heterotrophs obtain their sources of carbon from? Parasites – absorb nutrients from living host organisms Saprobes – absorb nutrients from decomposing, dead organic matter Respiration (Aerobic) Recall: What is cellular respiration? Cellularrespiration is the 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 (Anaerobic) 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. Comparing Reproduction (Asexual)  Bacterianormally 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! Binary Fission (asexual reproduction) Steps in Binary Fission: 1.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. END RESULT: 2 identical daughter cells Conjugation (sexual reproduction)  Conjugation – A 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.  The Result: Bacteria have now altered their genetic material! What are Plasmids? ?  What are endospores for? Bacteria form endospores when growing conditions are extremely unfavourable Endospores form a thick wall that surrounds the DNA and cytoplasm Endospores will remains dormant until conditions Endospor are favourable for growth e of Bacillus sp. 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 Escherichia produce endotoxins  Exotoxins – highly toxic molecules released when bacteria multiply. Examples of endotoxin diseases: tetanus and botulism Question: How are various bacteria used in helpful ways? Bacteria in the soil… Nitrogen-fixing bacteria live freely in the soil or within the root nodules of plants. These bacteria can convert nitrogen from the air into nitrates for plant use. Other bacteria feed on decomposing, dead material. They release carbon dioxide back into the atmosphere. In Sewage Treatment… To help breakdown organic matter (ex. human fecal waste) at the local water treatment facility before water is placed back into Lake Ontario To clean oil spills… Bacteria are used to eliminate or neutralize toxic compounds in the environment (ex. baceria used to help clean up BP Oil Spill) Bacteria in our food… Lactic acid bacteria is commonly used in the production of dairy foods such as yogurt to help the sugars ferment and produce acids that give yogurt it’s natural taste