Presentation on theme: "Objectives To understand the structure of bacteria"— Presentation transcript:
1Objectives To understand the structure of bacteria Compared to virusesUnderstand Eubacteria vs. ArchaebacteriaHow bacteria classifiedKingdom, phyla, etc.How bacteria reproduceUses and harmful effects of bacteriaHow to prevent bacteria
3How Human are you?There are more microbial cells in our bodies than there are human cells!Of the 100 trillion cells that make-up the human body 90 trillion are bacterialHumans are ~90% BacterialEveryone has about 1 kg in weight of bacteria in their gut.Each gram of feces contains 100,000,000,000 (100 billion) microbes.Human adults excrete their own weight in fecal bacteria every year.
4Bacteria: Structure CELLS (living) Prokaryotic (No nucleus or MBO’s) Genetic Material (DNA)Cell Membranes and Cell Walls
5Classifying Prokaryotes DOMAIN BACTERIA – Kingdom EubacteriaSingle-celled prokaryoteHave peptidoglycan cell walls (protein carbohydrate)Can form colonies of clumps or filaments.Three basic shapes: Cocci (round), bacilli (rod) & spirilla (spiral)Strepto – occurs in chains.Staphylo – occurs in clusters..
6Basic Structure Cell wall – protects the cell & gives it shape. Outer membrane – protects the cell against some antibiotics (only present in gram-negative)Cell membrane – regulates movement of materials into & out of the cell; contains enzymes important to cellular respiration.Basic StructureRibosomeCell MembraneCell WallPilliDNA (circular = plasmid)PeptidoglycanFlagella
7DNA (circular = plasmid) Plasmid – circular piece of DNA that contains some genes obtained through genetic recombination.Capsule & Slime layer – protect the cell & assist in attaching the cell to other surfaces.
8Classifying Prokaryotes DOMAIN ARCHAEA – Kingdom ArchaebacteriaGenes that resemble eukaryotic genes & some that resemble prokaryotes.Have unusual lipids in their cell membranesFound in EXTREME environments!Cell walls lack peptidoglycanHave introns in their DNASingle-celled prokaryote
9Archaebacteria Methanogens Convert H2 & CO2 into methane CH4 Anaerobic bacteria (no oxygen… early Earth)Found in bottoms of swamps, sewage & intestinal tracts of animals.Extreme HalophilesSalt lovingFound in Great Salt Lake & Dead SeaThermoacidophilesLive in extreme acidic & hot environment
10Archaebacteria vs Eubacteria Type of environment: EXTREMECell Wall composition:LACKS PEPTIDOGLYCANType of environment:COMMONCell Wall composition:PEPTIDOGLYCAN
11Prokaryote EvolutionFossil Evidence indicates bacteria existed about 3.5 billion years ago.Eukaryotes existed about 2.5 billion years ago (Theory of symbiosis)Bacteria evolved to adapt to almost any environment, from ocean trenches to thermal vents.
12Identifying Prokaryotes Prokaryotes are identified by characteristics such as:the way they obtain energyshapetype of cell wallthe way they move
13V. Ways Bacteria are Identified I. Shapes of Bacteria:a. Bacilli - rod-shaped
14b. Cocci - round shapedStaphylococcus - cocci inclustersStreptococcus - cocci in chainsDiplococcus - cocci in pairs
16How do bacteria obtain and use energy? AUTOTROPHIC OR HETEROTROPHIC BACTERIA ARE EITHERAUTOTROPHIC OR HETEROTROPHICChemoheterotrophs – organisms that must take in organic molecules for both energy and a supply of carbon.Photoheterotrophs – organisms that are photosynthetic, but still need to take in organic compounds as a carbon source.Chemoautotrophs – make organic carbon molecules from carbon dioxide and other inorganic compounds using energy from chemical reactions.Photoautotrophs – use energy from sunlight to convert carbon dioxide and water to carbon compounds.
17Releasing EnergyObligate aerobes – organisms that require a constant supply of oxygen in order to live. EX: Mycobacterium tuberculosis, the bacterium that causes tuberculosis.Obligate anaerobes – do not require oxygen; some may be killed by O2! EX: Clostridium botulinum, found in soil and can grown in canned food causing fatal food poisoning.Facultative anaerobes – can survive with or without O2. EX: E. coli, can live in the large intestines contaminated water.
18Growth & ReproductionBinary Fission – bacterium doubles in size, it replicates its DNA and divides in half. ASEXUAL
19Growth & ReproductionConjugation – the process by which two living bacteria bind together and one bacterium transfers genetic information to the other.Sex pili
21Growth & ReproductionEndospore – adaptation that protects the cell against harsh environmental conditions, such as heat and drought. May allow the bacterium to survive for thousands of years.
22How do Bacteria benefit humans and ecosystems? 1. Decomposers – recycle nutrients: break down the nutrients in dead matter & atmosphere.2. Nitrogen – Fixing Bacteria (Nitrogen fixation)Live freely & symbiotically with plantsRhizobium; converts N2 into a form of nitrogen plants can use.Found in legumes (bean type plants)3. Aid in digestion – live symbiotically within our GI tracts and help us extract nutrients
24Importance of Bacteria Phylum CyanobacteriaPhotosyntheticEutrophication or Population Bloom – the sudden increase in the number of cyanobacteria due to a high availability of nutrients.Leads to anoxic environment (dead zone)
25Human Uses of Bacteria Food – baking & beverages Clean up oil spills, rivers & streamsPharmaceuticalsAide in digestion (symbiotic relationship with bacteria in our guts)
26Bacteria & Disease Pathogen – any disease-causing agent Only 1% of bacteria are pathogenic!Exotoxins – toxic proteins secreted by bacterial cells, includes some of the most potent poisons known.Clostridium botulinum – one gram of the exotoxin that causes botulism could kill 1,000,000 people!
27MRSAStaphylococcus aureus – harmless, found on skin; if it enters the body through a wound it can cause layers of skin to slough off, vomiting, severe diarrhea & deadly toxic shock syndrome.MRSA = methicillin resistant Staphylococcus aureus
30Antibiotics: how we TREAT bacterial infections Antibiotics are drugs that combat bacteria by interfering with various cellular functionsSome bacteria are antibiotic-resistant and destroy antibiotics, or prevent entry of the antibiotic into the cytoplasm.
31AntibioticsBacteria can be tested for their sensitivity to antibiotics by growing them in a petri dish with paper disks containing different antibiotics.As the antibiotics diffuse into the agar, the bacteria’s growth will be inherited by the antibiotics if the bacteria are sensitive to that antibiotic.
32Bacteria & DiseaseEndotoxins – are NOT secretions; but components of cell walls in bacteria: glycolipids, which are large molecular complexes of polysaccharides & lipids.All endotoxins induce the same general symptoms: fever, aches and sometimes a dangerous drop in blood pressure (shock).Salmonella – produces endotoxins that cause food poisoning & typhoid fever.
33Bacteria & Disease Lyme Disease Most widespread pest carried disease in U.S.Caused by Borrelia burgdorferi, a bacterium carried by ticks that live on deer & field mice.Antibiotics can cure the disease if administered within a month of exposure.If untreated, it can lead to arthritis, heart disease & nervous disorders.
34Bacteria & DiseaseYersinia pestis – the bacterium that causes bubonic plague throughout Europe.Infected rodents fleas humans.