Biol 2051 Exam 1 Questions Answered Correctly (Already Passed)

Biol 2051 Exam 1 Questions Answered Correctly (Already Passed) An important assumption of molecular sequence comparisons to generate phylogenies is _____ - Answers species that share a more recent common ancestor will have fewer differences than species that have been separated for longer periods of time The cell wall is constructed _____ in all three domains - Answers differently If there are 5 nucleotide differences between species A and B, 12 between species A and C, and 14 between species B and C, one can conclude _______ - Answers species A and B shared a common ancestor after they shared a common ancestor with C Which came first: DNA, RNA, proteins, lipids? - Answers RNA What is the most likely sequence of events that took place to generate the first cells? - Answers Form RNA; Form catalytic molecules; Assemble membranes Bacteria are able to occupy more habitats than eukaryal cells because they - Answers have greater metabolic diversity Anoxygenic photosynthesis differs from oxygenic photosynthesis in that - Answers anoxygenic photosynthesis does not produce oxygen, while oxygenic photosynthesis does What are Koch's postulates? - Answers -The microbe must be isolated and cultured in the lab. -The microbe must be found in all organisms with the disease, and absent in all organisms without the disease. -When inoculated into a susceptible host, the microbe must cause the disease. Pasteur's famous experiment with swan-necked flasks showed - Answers broiling broth media killed whatever microorganisms may have been present; whatever was responsible for causing broths to turn turbid came from the air (bacteria do not spontaneously generate) An important finding from Edward Jenner's vaccination experiment is - Answers immunity to one microorganism can be conferred by exposure to a closely related microorganism. The key features of living organisms include - Answers -metabolism and growth -reproduction and genetic variation -ability to respond to external stimuli -homeostasis Macromolecule types found in all cells - Answers polysaccharides, proteins, lipids, and nucleic acids Repeating subunits of proteins are called - Answers amino acids Polysaccharides are composed of repeating units called - Answers monosaccharides Lipids are composed of - Answers a hydrocarbon chain linked to a glycerol molecule. The domains of living organisms include - Answers -eukarya - cells that have a membrane-bound nucleus -archaea - simple, single celled organisms that manufacture mRNA and proteins in a manner similar to eukaryotes -bacteria - simple single celled organisms that synthesize mRNA and proteins Why are microbes useful models in research? - Answers Many microbes can grow rapidly on inexpensive media and be genetically manipulated easily; can be cultivated in lab; have metabolic and regulatory pathways that are very similar to those found in more complex organisms; can be used for large-scale production of chemical compounds and useful macromolecules. How did the first membranes form resulting in something resembling a cell? - Answers Since lipid bilayers can spontaneously assemble from lipids in an aqueous solution, it is possible that they formed around mineral aggregates trapping information RNA and basic building blocks inside to generate something similar to a cell How did mitochondria arise in eukaryal cells? - Answers Mitochondria contain a DNA molecule that encodes a primitive ribosome similar to that of bacteria. Mitochondria arose when a bacterial cell was engulfed inside of an archaeal or early eukaryotic cell. The bacterial cells provided ATP to the host cell while the host provided protection as well as a steady food supply resulting in an endosymbiotic relationship. Endosymbiosis also led to the development of chloroplasts. DNA sequencing has affected our understanding of microbes by - Answers enabling us to more exactly determine the relatedness between organisms; determine the process by which evolution occurs; determine why similar bacteria can have very different properties. The endosymbiotic theory explains - Answers the origin of eukaryotes Eukaryotes originated over _____ years ago by endosymbiosis - Answers two billion purpose of PCR - Answers takes small amounts of DNA and produces large amounts of DNA Evidence that mitochondria in chloroplasts are derived from bacteria is - Answers the presence of their own DNA; presence of their own protein synthesizing machinery; similar 16s rRNA gene sequences transcription - Answers RNA synthesis from a DNA template Joseph Lister is famous for - Answers recognizing that cleanliness and disinfection greatly reduced the number of casualties in hospitals an important challenge in the global effort to battle infectious diseases - Answers access to vaccines and antibiotics is limited in many parts of the world; the development of resistance to common antibiotics; the lack of vaccines against several important diseases Bacteria do not have membrane-bound organelles but they do have inclusion bodies. Why would bacteria want to store these compounds? - Answers they are useful forms of energy In bacterial cells, you are likely to find which of the following molecules closely associated with the nucleoid of the cell? - Answers DNA & RNA polymerase and RNA If MreB protein is nearly always found in non-spherical bacteria, but rarely in cocci it suggests - Answers MreB is necessary for non-cocciness; MreB is a major shape determining protein; cocci is the default shape in bacteria A critical first step in bacterial cell division is - Answers the formation of the Z ring by tubulin-like FtsZ proteins Location of the Z ring in dividing bacteria is critical because - Answers it ensure the two daughter cells will be of equal volume The existence of Mycoplasmas, a group of small bacteria with no cells walls, suggests - Answers both cells walls are not a necessary condition for survival in bacteria and these organisms may occur in environments where the cell wall is not necessary The ability of bacteria to consistently and repeatedly move toward an attractant and away from a repellant is evidence that - Answers both a mechanism exists for bacteria to alter intracellular processes in response to external stimuli and bacteria are able to discriminate between attractants and repellants The difference between the taxonomic designations of strains and species is - Answers a single bacterial species can be composed of multiple bacterial strains Most archaea contain FtsZ and MreB-like proteins, suggesting cell morphology in archaea is likely determine similar to - Answers bacteria Gram-positive and Gram-negative flagella are composed from subunits of - Answers flagellin ______ arranges species into categories while _____ attempts to reflect the evolutionary relationships among species - Answers classification; phylogeny general size of bacteria - Answers 0.5 um to 5 um The cytoplasm of bacterial cells contains additional components including - Answers proteins, mRNA, ribosomes, and tRNA Inclusion bodies are - Answers large granules that serve as storage of particular nutrients Roughly half of the plasma membrane is composed of - Answers protein Plasma membrane is stabilized by - Answers hopanoids Plasma membrane is a bilayer formed by a mixture of ______ and is _______ - Answers phospholipids; amphipathic Chemotaxis involve chemoreceptors that - Answers sensing certain attractants or repellants, becoming activated and communicating with flagella via cytoplasmic proteins to control whether the flagella should continue to propel the bacteria forward or to reverse direction and cause tumbling instead Pili and fimbriae are both surface appendages but pili are involved in _____ and fimbriae are involved in ______ - Answers conjugal transfer of DNA; adhesion Biofilm - Answers surface associated communities of one or more species of bacteria staphylococcus - Answers spheres in clumps Bacteria have extra chromosomal pieces of DNA in the cytoplasm called - Answers plasm