Microbiology EXAM 1 chapters 1-7 Questions & Answers Already Passed!!

Microbiology EXAM 1 chapters 1-7 Questions & Answers Already Passed!! • What organisms are considered microorganisms and are the subjects of study in microbiology? Microorganisms are Prokaryotes(bacteria & archaea) and eukaryotes(protozoa, algae, some fungi and helminths). Microbiology also includes studying viruses . Which two are encompassed by the term prokaryotes? bacteria and archaea What are some examples of "small" things that are not covered by microbiology? Are all prokaryotes microbes? insects, macroscopic fungi, algae, and individual cells of macroscopic organisms. YES all prokaryotes are microbes. • Why are helminths (complex, multicellular animals) covered under microbiology? because their infective forms are MICROSCOPIC. cause infectious disease in microscopic forms. • What are general size ranges of eukaryotic microbes, Bacteria and Archaea, and viruses? Bacteria/archaea= 1-10 um Eukaryotes= 10-100 um viruses= 0.02-0.2 um • Electron microscopy is generally required to visualize what type of microbe? Which types can generally be visualized by light microscopy? bacteria cells and viruses.Eukaryotes and bacteria can generally be visualized by light microscopy • Approximately how long have microbes been present on Earth? Which types of microbes were first to appear? 3.5 billion years for prokaryotes(bacteria/archaea) and 1.8 billion years for eukaryotes Approximately when did Cyanobacteria first appear, and what impact did their evolution have on Earth's atmosphere? 2.5 million years ago. they are responsible for making oxygen in the environment (aerobic respiration) and paved the way for extracellular life. • What are some examples of ways in which humans make use of microbes and their products or activities? Biotechnology- when humans manipulate microorganisms to make products in an industrial setting Genetic engineering- manipulates genetics of microbes plants and animals for the purpose of creating new produces EX) cheese, bread, alcohol, yogurt, sauerkraut, kimchee, chemicals and antibiotics • What is the human microbiome? How does the number of total microbial cells present in the human microbiome compare to the total number of human cells in the body? the human microbiome is a set of microbes that are present on a typical human. Microbes outnumber our own cells by >10 fold. • Do most microbes associated with humans (or plants) cause disease? Be able to interpret Table 1.1 in the textbook regarding the comparison of the number of deaths caused by microbes (infectious diseases) vs. other causes. Most microbes cause no harm. 10 billion new infections cause every yr from microbes. infectious disease are among the most common causes of death in the U.S. and world wide. • What were the contributions of the following prominent microbiologists? Antonie van Leeuwenhoek, Louis Pasteur, Ferdinand Cohn, Joseph Lister, Robert Koch, Alexander Flemming. Leeuwenhoke- First person to see bacteria invented/advanced the microscope Hook- first person to see microbes Pasteur- Disproved spontaneous generation (swan necked flask experiment) Cohn- Discovered heat resistant endospores and steralization Lister- first person to introduce aseptic technique Koch-Developed a series of postulates that verified pasteurs germ theory of disease and established a link between microbes and the disease it caused Flemming- discovered antibiotics in 1928 • What is the germ theory of disease? How did the ability to grow microorganisms in pure culture contribute to the germ theory of disease? germ theory of disease is showing that human diseases could arise from infection. Koch's Postulates would provide absolute proof that a specific microorganism was the cause of a particular disease: 1)The suspected causative microorganism must be present in every individual with the disease. 2)The causative microorganism must be isolated and grown in pure culture. 3)The pure culture must cause the disease when inoculated into an experimental animal. 4)The causative microorganism must be re-isolated from the experimental animal and reidentified in pure culture. • How is binomial nomenclature correctly used to write the name of a given microbe? What do "generic" and "specific" names refer to? - combination of the genus(capitalized) and species(lowercase) -italicized when written in print -underlined when written by hand - genus name can be abbreviated to the first initial • What are some important differences between Whittaker's 5 Kingdom tree of life and the Woese-Fox 3 Domain tree of life? Which of these incorporates the comparison of molecular characteristics such as DNA and protein sequences? What are the three Domains of life? -whittakeers 5 kingdom includesanimals, plantss, fungi, protists and monera. Based on MORPHOLOGICAL or CHEMICAL characteristics. -Whose-Fox system is based on analysis of gene (DNA). consists of 3 domains(bacteria, archaea and eukarya) • What are four structures that all Bacteria possess? What are three structures that most Bacteria possess? Which are present in only some Bacteria? ALL bacteria- Cytoplasm, cell membrane, ribosomes, chromosomes MOST bacteria- cell wall, glycocalyx,cytoskeleton SOME bacteria-Flagella, Phili, fimbriae, outer membrane, plasmids, inclusions, micro-compartments, endospores, intracellular membrane. • What two structures generally control the morphology of a bacterial cell? What are some common morphologies of bacterial cells? What does pleomorphic mean? cell wall and cytoskeleton. Pleomorphic means that cells may very in shape and size caused by variations in cell wall structure. Common morphologies are coccus, rods, filaments, spirillum, vibro and spirochete. • How does the general conservation of cell morphology and arrangement within a given species or group of microbes aid microbiologists in the study of microbes? helps identify different types of bacteria. • What is the major function of bacterial flagella? What energy source is used to power flagellar rotation? swimming motility. Powered by proton motive force which is in the cell membrane. • What are four different types of flagellar arrangement on the cell? Monotrichous(one flagellum), lophotrichous(small bunches), amphitrichous(two at each poles), peritrichous( randomly dispersed over the surface of the cell) • What is chemotaxis? What are some examples of other types of taxes (plural of taxis)? Chemotaxis is how bacteria move in response to chemical signals. ex. of other types include phototaxis(response to light) and aerotaxis(response to oxygen) • Which direction of flagellar rotation (CCW or CW) results in "running", and which results in "tumbling"? How can the relative balance of running vs. tumbling result in chemotaxis toward an attractant? CW= tumbling, reverses. a change in orientation course. CCW= running, forward movement. -toward an attractant we want to increase the time CCW rotation in proportion to CW when favorable conditions are sensed. • How do the structure (i.e. number/cell and length) and functions of pili and fimbriae compare? Which of these structures can be involved in twitching motility and DNA exchange by conjugation? Pili=longer than fimbriae(1-2um) few per cell. Involved in twitching motility and DNA exchange by attachment. fimbriae= short (0.1-0.2 um) many per cell. • What are two major types of glycocalyx, and what is the major macromolecular component of glycocalyx? two types are a capsule and a slime layer. The major macromolecular component is protein and polysaccharides. What are some similarities and differences between capsules and slime layers? Capsules are more tightly attached to the cell and slime layers are more loosely attached to the cell and extend farther away. BOTH are used for adhesion and biofilm formation and serve as a protective layer. What role does glycocalyx play in biofilm formation? a protective layer that can allow resistance to antibiotics and desiccation as well as protection from phagocytosis by immune cells. • What is the major macromolecular component of the S layer, and what are two functions of this structure? composed of crystalline layer of 1,000 copies of a single type of PROTEIN. Functions as protection and attachment to surfaces. • What are the two major components of peptidoglycan? What structure in Bacteria is made of peptidoglycan, and what are two important functions of peptidoglycan -Long Glycan (sugar) & a short Peptide (protein). -The cell envelope structure in bacteria is made of peptidoglycan. It is important for: (1) strength to resist rupturing due to osmotic pressure (2) for conferring cell shape. How does peptidoglycan thickness compare in Gram positive and Gram negative Bacteria? Gram positive= thick layer Gram negative= Thin layer • What are some major differences in the cell envelope composition between Gram positive and Gram negative Bacteria? What are some similarities? Be able to identify structures in G+ and G- cell envelopes shown in Figure 3.15 in the textbook. Gram positive= thick cell wall (20-80nm), no outer membrane, teicholic acid, lipoteichoic acid. negative charge. No periplasmic space. Gram negative= Thin (1-3nm) cell wall, cytoplasmic membrane, outer membrane, proteins, lipoproteins, porins, phospholipids and lipopolysaccharide, periplasmic space. SIMILARITIES= peptidoglycan layer, cytoplasmic membrane, membrane proteins. • What are four steps in the Gram stain procedure, and what types of Bacteria does this stain differentiate? 1) add crystal violet (+ and- are purple) 2)Grams iodine- mordent lets the Peptidoglycan really stick in especially in gram +. 3) alcohol- dissolves lipids in outer mem. removes dye in Pep. layer in gram neg cells . 4) safranin- counter stain makes gram - cells pink Be able to deduce what the result of a Gram stain would be if one of the procedures were omitted (e.g. what would happen if the iodine, alcohol wash, or safranin counterstain step were omitted)? if omitted.... iodine: dye won't form large complexes in pep. layer. dye wont be trapped in walls. Alcohol: won't remove dye from gram neg cells. would stay purple. safranin: gram neg cells would be unseen(clear). • What is a major component of the cell wall of acid-fast bacteria, and what sort of cell envelope structure do acid-fast bacteria have (similar to G+ or G-)? Mycolic acid. have a modified gram positive structure. • What is a component of the cytoplasmic membrane in bacteria such as Mycoplasma spp. that lack a cell wall, and what role does this component play? • What are the two major components of the cytoplasmic (or cell) membrane? What are some important roles of the cytoplasmic membrane? lipid bilayer (30%-40%) with proteins(60-70%). A major action of the cell membrane is to regulate the passage of nutrients into and out of the cell. provides a site for reactions contains enzymes of respiration and ATP synthesis. • What are the relative permeabilities of the cell wall, cytoplasmic membrane, and periplasmic (or outer) membrane? How might this play a role in differences in antibiotic or disinfectant resistance between Gram positive and Gram negative Bacteria? -cell wall is the most permeable, outer membrane is less permeable than cell wall, cytoplasmic membrane is the least permeable of the 3. -Gram neg have an extra later of protection they are more resistant than gram positive due to their outer membrane. • What component of the bacterial cell envelope can act as an endotoxin, and in what structure and type of bacteria is this component found? lipid A in LPS of gram negatives and the cell wall components of gram positives. • What are two typical characteristics of the bacterial chromosome, and how do these compare to eukaryotic chromosomes? Exists in the form of a SINGLE, CIRCULAR chromosome (single strand of DNA). Their DNA is not enclosed in a nucleus but arranged in a dense area called the nucleoid • What is a similarity and difference between bacterial and eukaryotic cytoskeleton? Similarity= particularly the cocci ,other bacteria produce long polymers of proteins that are very similar to eukaryotic actin Difference= these fibers contribute to cell shape, perhaps by influencing the way peptidoglycan is manufactured and also in cell division. • What are inclusion bodies and microcompartments, and what roles do they play in Bacteria? Inclusion bodies=non- membrane bound granules used for storage of nutrients for later use, Microcompartments=outer protein shell contains specific enzymes that work together in a given metabolic pathway. • What are endospores and in which genera and type (G+ or G-) of bacteria are these structures found? endospores are dormant bodies produced by bacteria such as bacillus, clostridium, and sporosarcina. Both gram + and - bacteria can form them but the medically relevant ones are all gram + • What are some stresses that endospores can withstand, and how does this compare to vegetative cells? more resistant than vegetative cells. Resistant to heat, radiation, freezing and desiccation, resistant to a variety of chemicals, not affected by many antibiotics due to dormant state. Under what conditions are endospores formed? Is endospore formation and germination generally a reproductive process? Why or why not? typically in response to poor conditions for growth. NOT a reproductive process because they only form one endospore. one spore typically germinates to form one cell.