BIOL 1108 1nd EditionExam # 2 Study Guide Lectures: 7 – 11Lecture 7 (September 22)Bacteria and Archaea Learning Objectives1. Know the defining features that distinguish eukaryotes and prokaryoteso Prokaryotes- no nucleus or major organelles (bacteria/arachaea) Circular chromosomes (plasmids) Reproduce by binary fission Smaller, fewer genes and DNAo 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 Bacteriao 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 porousand 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 metabolismo 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 environmento 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 food6. 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 antibioticwith 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 ofthe 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 fissiona) Lag Phase: Upon initial inoculation there will not be any cell divisionb) 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 HABITATS1. 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-