BIOL 1108 1nd Edition Exam 2 Study Guide Lectures 7 11 Lecture 7 September 22 Bacteria and Archaea Learning Objectives 1 Know the defining features that distinguish eukaryotes and prokaryotes o Prokaryotes no nucleus or major organelles bacteria arachaea Circular chromosomes plasmids Reproduce by binary fission Smaller fewer genes and DNA o Eukaryotes nucleus and cellular organelles animals plants fungi protists Linear chromosomes Reproduce by mitosis meiosis 2 Be able to define the Archaea and know how to distinguish them from Bacteria o Archaea consists of single celled organisms that are prokaryotic They don t have a nucleus or any membrane bound organelles While similar in shape and size to bacteria archaea have some metabolic pathways that are similar to eukaryotes Archaea have a different cell membrane composition that is chemically different from bacteria and eukaryotes This cell membrane is made up of a backwards glycerol molecule ether link rather than esther link and also lacks peptidoglycan Archaea can also form a lipid bilayer and can live in harsh environments extremophiles o Bacteria have a cell wall made of peptidoglycan that makes the wall relatively porous and rigid 3 What is meant by the term Exponential Growth How can you relate this to what happened in the E coli long term evolution experiment o Increase in population growth when resources are abundant and reproductions occur physiological capacity Ex E Coli strains continued to grow and double at an increased rate when they were constantly presented with unlimited food for more than 20 years 4 What role s do bacteria play in human biology o Bacteria in the gut provide immunity essential vitamins and aid with metabolism o Prepionibacterium acnes cause acne in humans There are 3 different strains types of acne Two of them actually cause acne while the other doesn t Scientists are hoping to replace acne causing bacteria while the non acne strain as a way to help people get rid of acne 5 What are the advantages and disadvantages of having a bacterial cell wall o Advantages Keep viruses from attacking the cell Give cell shape Keep cell from bursting Allow components to be excreted into the environment o Disadvantages Pilli are needed to exchange genes because the bacterial cell wall prevents two bacterial cells from fusing their membranes and exchanging genes conjugation The rigid cell walls prevent form ingesting food 6 What constitutes the microbiome o The microbiome is the population of microorganisms that live within or on the human body which is approximately 10 times the number of cells in the human body The microorganisms can live in the mouth gut intestines and other places They can have beneficial qualities as well as some dangerous qualities Some bacteria are essential to digesting food and synthesizing important vitamins and nutrients A microbiome is unique to the individual 7 How might the use of antibiotics and antimicrobial products be changing the microbial environment o Antibiotics and antimicrobial products change the microbial environment by providing a barren environment for drug resistant bacteria to thrive on o They disrupt natural flora of good bacteria in the microbiome Like deforestation antibiotics remove all the good bacteria 8 What is meant by antibiotic resistance and by what mechanisms can bacteria become resistant to antibiotics o Antibiotic resistance is when some bacterial microorganisms are able to survive after being exposed to an antibiotic and have adapted to them which makes antibiotics less effective in treating bacterial infections This allows the resistant bacteria to continue multiplying regardless of the presence of antibiotics Bacterial resistance can occur by genetic mutation or by acquiring resistance from another bacterium conjugation Bacteria can destroy antibiotics with enzymes inactivate the antibiotic with enzymes or actively pump the antibiotic out of the cell with enzymes In The News Why do some U S senators propose funding for NOAA buoys that are deployed as part of the GOA ON Ocean acidification reduces the formation of shells for organisms and destroys the marine diversity in coral reefs As CO2 dissolves in water it forms carbonic acid and lowers the pH of the oceans As the water gets more acidic it competes for carbonate ions and many marine organisms cannot secrete the calcium carbonate shells or skeletons they need to survive Organisms can still secrete calcium carbonate but it takes more energy to do so Predicted future CO2 levels have been found to alter sensory responses and behavior of marine fishes Changes include increased boldness and activity loss of behavioral lateralization altered auditory preferences and impaired olfactory function Even with the largest estimate of CO2 from volcanoes it pales compared to the amount produced through human activity BACTERIAL GROWTH Under ideal growth conditions bacteria can double their population size in a matter of minutes as opposed to hours or even days for most unicellular eukaryotes Exponential Growth increases proportional to current value Bacteria are asexual and can double in numbers quickly through binary fission a Lag Phase Upon initial inoculation there will not be any cell division b Log Growth Phase If resources are unlimited maximum cell division will occur c Stationary Phase When resources become scarce cell division will cease d Log Death Phase Once resources are fully depleted the population crashes BACTERIAL HABITATS 1 Hydrothermal vents Giant tube worms near hydrothermal vents rely on chemosynthetic bacteria in their body cavity to produce food for the animal host 2 Human Body The human body is composed of approximately ten trillion cells The number of bacteria in and on the human body is at least ten times as many hundred trillion cells Different parts of the body have different distributions of bacteria A newborn s close physical contact with their mother is the primary source for microbial flora both on the skin and in the intestinal tract Acne is associated with two of the strains but individuals with the third strain of P acnes appear to be free of acne The bacterium prevents other species from becoming established on the skin About 60 by dry weight of human feces is made up by gut bacteria ANTIBIOTICS Antibiotics can wipe out the natural flora that inhabits the human intestinal tract This is like clear cutting a forest in which all sorts of weeds can colonize the barren biological