Download Microbiology final /portage and more Exams Microbiology in PDF only on Docsity!
Microbiology final /portage/update
2024/quick pass
Microbiology is the study of what - microorganisms/viruses and there biological processes What is the smallest biological unit of life? - cell What is a macromolecule? - a molecule containing a very large number of atoms, such as a protein, nucleic acid, or synthetic polymer. What are the 4 main types of macromolecules - proteins, carbohydrates, lipids, polysachrides What various functions do proteins have in a cell - Proteins may facilitate the movement of materials in or out of a cell. Some can act as enzymes that catalyze, or speed up, biochemical processes. Others play a structural role while other proteins, such as filaments, enable movement. What are the two major types of nucleic acids and their roles? - There are two major types of nucleic acids: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). DNA contains a vast amount of hereditary information and is responsible for the inheritable characteristics of living organisms. RNA is responsible for deciphering the hereditary information in DNA and using it to synthesize proteins. Nucleic acids are chemical molecules that carry genetic information within the cell
What is the plasma membrane and what is it made up of? - The plasma membrane serves the cell as a surrounding barrier that separates the inside of the cell from the outside surrounding environment. the plasma membrane also restricts the movement of materials (water, nutrients, etc) either in or out of the cell, thus allowing a cells to absorb and keep what is needed (influx) while also preventing the escape (out flux) of essential nutrients. The plasma membrane is composed of lipids (hydrophobic hydrocarbons). What are the three main components of polysaccharides? - carbon, hydrogen oxygen atoms. Examples would include, C6H12O6 (glucose) C12H22O11 (sucrose) C6H10O5 (cellulose). What is the primary difference between prokaryotic and eukaryotic cells? - Eukaryotic cells contain a nucleus, a membrane enclosed region within the cell that contains the genetic material. Prokaryotic cells do not have a nucleus and can be further classified as either Bacteria or Archaea. What are the main morphologies of bacteria? - Bacteria can be described as coccus (round/spherical), bacillus (rod), vibrio (curved rod) spirillum (spiral/corkscrew). Which group (classification) of bacteria is noted for its ability to survive under harsh conditions? - Archaea.
What are usually metal ions known to assists enzyme during the catalysis reaction? - Cofactors Define catabolism - the breakdown of complex molecules in living organisms to form simpler ones, together with the release of energy; destructive metabolism. Upon cellular injury, which metabolic process is involved during the growth and repair phases of the cell? - The anabolic process is involved in the building up of small complexes into larger complexes. Describe the energy transfer process relative to both ATP and ADP. - ATP has the energy (phosphate group) to donate while ADP can accept energy in the form of a phosphate group. Thus, ATP can be reduced (ATP →ADP + Pi) while ADP can be built into ATP (ADP + Pi →ATP). an organism that derives its energy (generates ATP) from photons of light is called a _________ - Phototrophic microorganism. An organism that derives its energy by removing electrons from elemental sulfur would be classified as a __________? - Lithotroph A reactive intermediate would be present in which phosphorylation process? - The chemical compound losing the phosphate group is referred to as the phosphorylated reactive intermediate. Identify the products of the following chemical equation: Glucose + 2NAD+ → 2 NADH + 2 Pyruvate + 2 ATP - The products are to the right of the arrow: 2NADH, 2 Pyruvates and 2 ATP What is the primary byproduct of the TCA cycle? Select all that apply. A. NAD+ B. FAD C. NADH
D. FADH2 - C and D. The TCA cycle produces an abundance of reduced electron carriers (NADH and FADH2). True or False. The reactants of the TCA cycle directly enter and fuel the electron transport system. - False. The products of the TCA cycle (reduced electron carriers) enter and drive the production of ATP via the electron transport system. In the absence of glucose, which of the following can be used as alternative energy sources? Select all that apply. A. Lactose B. Nucleic acids C. Carbohydrates D. Lipids - A, C, D can all be used as alternative energy sources. For the catabolism of proteins and lipids, which of the following enzymes are used? Select all that apply. A. Ligases B. Proteases C. Transferases D. Lipases - Proteases and lipase True or False. The β-oxidation pathway catabolizes the fatty acid chains of lipids. - True True or False. Plants, algae and bacteria all contain chloroplasts. - False. Chloroplasts are specific to algae and plants only. The process of carbon fixation begins with which of the following reactants: select all that apply. A. ATP B. Glyceraldehyde- 3 - phosphate C. CO D. NADPH E. H2O - A, C, D, and E. Carbon fixation uses the ATP/NADPH produced during light reactions to convert CO2 and H2O into useful sources of energy (carbohydrates).
A micrometer is defined as A. 10- 3 B. 10- 6 C.10- 9 D. 10- 12 - B. A micrometer is one-millionth of a meter. True or False: A nanometer is longer than a micrometer. - False. A nanometer is 1,000 times smaller than a micrometer. Resolution and contrast are two critical factors that influence your ability to see an object. Explain each. - Resolution - the distance between two objects at which the objects still can be seen as separate. Contrast- is the difference in light absorbance between two objects. For instance, trying to identify 2 dark colored objects at night (low light = low contrast) versus the same 2 objects in the middle of a sunny afternoon (bright light against 2 dark objects = high contrast). Assuming a fixed ocular, identify the part of the microscope you would adjust to enhance the magnification of a sample. A. Objective B. Condenser C. Iris diaphragm D. Eye piece - A. Only the oculars (eyepiece) and the objectives contribute to the magnification of the sample. Since the eyepiece is fixed, only the objectives could be altered. What is the total magnification (relative to your eye) of a sample imaged with a 20x objective and a 15x eyepiece? Show your math. - 20 x 15 = 300x magnification
True or False: A cell that is adherent, flat (thin) and unstained is easily identified using bright field microscopy. - False. Adherent, flat cells are almost invisible due to the limits on both resolution and contrast. Which of the following could be seen clearly by the unaided eye? Select all that apply. A. Bacteria with diameter of 24 μm B. Protozoa with diameter of 150 μm C. Virus with a diameter of 0.2 μm D. Skin cell with diameter of 1500 μm - B and D. The unaided eye can, on average, clearly resolve objects > 100 μm For each of the following questions select from the list below the single best answer: Phase-Contrast Dark Field Fluorescence Confocal This type of microscope is best suited for visualizing GFP, RFP and YFP proteins. - Fluorescence This type of microscope can provide detailed images of live cells without staining. - Phase- Contrast This type of microscope is used to greatly increase the contrast between samples and background by reflecting light off of the specimen. - Dark Field This type of microscope is capable of capturing images in multiple focal planes, rendering a specimen in 3D - Confocal Gram-Positive cells appear _______ in color due to a ______ peptidoglycan layer in the cell wall. - Purple; Thick Gram-Negative cells appear _______ in color due to a ______ peptidoglycan layer in the cell wall. - Pink; Thin
A researcher is asked to determine which of two vials contains E coli and which contains Salmonella. Knowing both are Gram-Negative while only one of them is capable of fermenting lactose, which type of media would be best suited: A. Growth media B. Differential media C. Selective media D. Selective and Differential media - B. Differential media distinguishes between two, often related, microbes. What are the requirements of a fastidious microbe? - A fastidious microbe is an organism with complex growth requirements such that if absent it will not grow. Enriched medias thus contain these specific and essential nutrients required for the growth of a particular subset of microorganisms. True or False: LB agar is classified as a non-selective, non-differential media. - True. LB agar is the most basic type of agar and like LB media supports the growth of virtually all microbes without restriction. The polysaccharide-based hardening agent added to LB media to produce LB agar is derived from what? - Seaweed (algae) extract. Blood agar is which type of medium? A. Differential B. Selective C. Enriched D. Selective and Differential - A. and C. Blood agar can be used to differential between species based on its hemolytic activity. It is enriched with red blood cells. Match the following hemolytic class with its description of activity. - 1. Alpha hemolysis B A. No hemolytic activity
- Beta hemolysis
C
B. Incomplete hemolytic activity
- Gamma hemolysis A C. Complete hemolytic activity Columbia CNA agar is most closely related to which media: A. Trypticase Soy Agar B. MacConkey Agar C. Blood agar D. EMB agar - C. CNA agar is similar to BAP as it is also enriched with blood and allows for differentiation based on hemolytic patterns. True or False: Chocolate agar gets its brown color from cocoa to produce an enriched media. - False. Chocolate (cocoa) is never added to the media. The name is derived simply based on the color that actually comes from the presence of 'cooked' (lysed) red blood cells in the media. A researcher is studying a strain of E. coli currently growing on a MacConkey plate. However, the researcher can't remember if E. coli is Gram-Positive or Gram-Negative. Would a Gram stain be necessary to confirm? Why or why not? - No. A Gram stain would not be necessary, as only Gram-Negative microbes will grow on MacConkey agar. Thus, E. coli is a Gram-Negative microbe. In an attempt to detect the presence of the pathogenic strain of E. coli O157:H7, a researcher spread a culture onto a MacConkey agar with failed results. What type of agar should they (correctly) try next? Why? - The microbe should be plated on SMAC (Sorbitol-MacConkey agar) as it is specifically formulated to detect O157:H7. Pathogenic E. coli (O157:H7) cannot ferment sorbitol while non-pathogenic E. coli can ferment both soribitol and lactose. Therefore, colonies that ferment (acidic conditions; non-pathogenic) can be differentiated from non- fermenters (neutral to basic conditions; pathogenic).
True or False. When performing a dilution streak a new (or sterilized) loop must be used for each phase. - True. Failure to do so would prevent the establishment of a dilution gradient, as the same bacterial concentration would be spread across both phase regions. In order to encourage growth of a slow growing microbe what might a researcher do during a phase dilution streak? - A researcher may either (1) opt to perform only a 3-phase dilution streak or (2) pass the loop through the previous phase multiple times (as opposed to only once). True or false. Pathogenic strains of bacteria tend to grow slower than normal non-pathogenic bacterial strains. - True. Pathogenic strains of bacteria tend to grow faster than non- pathogenic strains at 37°C, so researchers may set incubators at 25°C to restrict its growth. When given an unknown bacterial sample the first step is to expand the current bacterial population. Which form of media best suites this need? Why? A. MSA agar B. LB media C. MacConkey agar D. Columbia CNA agar - LB media because all other forms were selective media meaning they could potentially inhibit the growth of the unknown sample. The culture should first be expanded then placed onto a selective/differential plate. When given an unknown bacterial sample the first step is to expand the current bacterial population. Which form of media best suites this need? Why? A. MSA agar B. LB media C. MacConkey agar D. Columbia CNA agar - Universal precautions means any and all samples, whether known or unknown, are to be treated as potentially hazardous (or pathogenic) materials. List at least 3 observations a researcher would be sure to note while assessing an unknown microbial sample. - A lab researcher would be certain to note:
- Size and shape
- Any observable motility
- Gram status (positive or negative)
- The presence of any chemical reactions
- Changes in color localized to the organism or the surrounding media
- Capture (or draw) images of any of the characteristics described above While observing an unknown sample of limited amounts, a researcher must determine the following observations: (1) the presence of any motility and (2) its Gram status using the same sample—the liquid sample cannot be divided. Which would you determine first and why? - You must determine motility before determining the Gram status. Motility requires a wet mount, while Gram staining requires heat fixing the sample. If one were to begin with the Gram stain the heat fixation process would kill the organism, making any observations regarding motility impossible. The correct approach would be to place the liquid culture on a glass slide and determine its motility status. Next, the same liquid culture can be heat fixed and Gram stained. A facultative anaerobe is a microorganism capable of growth under what conditions? - A facultative anaerobe is capable of growth under aerobic and anaerobic conditions. True or False. The Lancefield groups are used to subdivide antigenic groups of alpha-hemolytic Streptococcus. - False. The Lancefield groupings are used to subdivide beta-hemolytic Strep. Rheumatic fever displays ______ hemolytic activity and occurs when _______ is left untreated. A. Beta; Strep. Pharyngitis B. Gamma; Strep. Septicemia C. Beta; Rheumatic fever D. Alpha; Strep. Pharyngitis - A.. Beta; Strep. Pharyngitis Strep throat (also known as strep. Pharyngitis) can lead to Rheumatic fever if left untreated and displays beta-hemolytic activity. True or False. Under most circumstances, staphylococcus can be found in ~30% of human population where it remains pathogenic. - False. While staphylococcus can be found in ~30% of the human population, it remains non-symptomatic. When a bacterium neither harms nor benefits from the host from which it obtains nutrients, it is referred to as being ___________. - Commensal.
True or False. Tuberculosis is best identified by a Gram stain. - False. Mycobacterium show poor Gram staining and show be screened via an acid-fast stain. True or False. You can become infected with TB simply by sharing a drink with someone who is currently infected with TB. - False. As per the Center for Disease Control (CDC) guidelines, simply shaking someone's hand, sharing a drink or even kissing cannot spread TB. Identify the disease based on the following (select all that apply): It is a small, acid-fast rod usually remaining asymptomatic for up to 20 years. It affects the skin, nerves, upper respiratory tract and eyes of infected individuals. A. Tuberculosis B. Leprosy C. Scalded-skin syndrome D. Hansen's disease E. Bacterial conjunctivitis - B and D. Hansen's disease is simply another name for Leprosy. Leprosy is characterized by its ability to remain dormant for up to 20 years as well as the effects observed relative to the patients skin, nerves, lungs and eyes. True or False. Directly ingesting clostridium or its associated spores will not cause illness in adults. - True. Only the direct ingestion of the pre-formed toxin will cause disease. A 5-month-old child is given honey at breakfast and begins showing symptoms consistent with botulism. Would the child's illness be classified as foodborne, infant or wound botulism? - Infant. Although food (honey) is consumed, foodborne botulism is derived from improperly canned, low acid foods under anaerobic conditions. Such conditions were not described. No puncture wounds or injuries were described, ruling out wound. The child is suffering from infant botulism, as honey is a potential carrier of clostridium. The intestinal track of young children is still developing and clostridium is able to colonize and produce the associated toxin. True or False. There are currently no cures for tetanus - True. Although the symptoms can be treated it is only to manage the discomfort not to cure.
Identify the medical condition characterized by robust carbohydrate fermentation under anaerobic conditions, swelling of the infected areas and fever. - Gas gangrene. The key identifier here is the robust carbohydrate fermentation, which manifests as intense gas production and swelling—both trademark conditions of gas gangrene. The alpha-toxin perfringolysin is associated with which medical condition caused by Gram-positive anaerobic bacteria? A. Tetanus B. Botulism C. Gas gangrene D. Leprosy - C. Gas gangrene. The bacterium that produces the alpha toxin perfringolysin is aptly named Clostridium perfringens. You develop a fever, chills and pneumonia after recently using a warm midst vaporizer in an attempt to open your sinuses. What bacterial disease would a doctor suspect is causing your symptoms? Would the doctor suspect you contracted it from touching (potentially) contaminated doorknobs? - Legionnaires. No—legionella cannot be spread simply by direct contact between people. Legionella can only be transmitted through droplets small enough to be breathed in. True or False. Bubonic plague is often characterized by painfully swollen lymph nodes. - True. Which form of the plague is highly virulent? What does it target? - Pneumonic plague is highly virulent and targets the respiratory (lungs) system. Syphilis is caused by: - spirochete Treponema pallidum True or False. Chlamydia is an obligate parasite and as such can be grown on agar plates alone. - False. Chlamydia is an obligate parasite and requires a host (viable cells) for its growth. Match the following diseases with their respective symptoms if left untreated:
Smallpox virus - Smallpox virus Paramyxovirus Polio Virus True or False: Viral replication occurs after it attaches and enters the host cell. - True. The viral genome is never replicated before attachment and entry. Place the following viral life cycle steps in order beginning with viral attachment and provide a description of each step. Uncoating: Release: Replication: Attachment: Entry: New infection: - 1 - Attachment: viral receptors bind to host proteins on the surface of the cell 2 - Entry: the virus fuses with the host membrane and enters the cell 3 - Uncoating: the viral capsid disassembles 4 - Replication: the viral genome is the 'blueprint' to make copies of itself 5 - Release: New virus particles are produced and leave the cell 6 - New infection: newly produced viruses that left the host cell now go on to infect new cells. A virus that infects bacteria is called a ____________ and contains a _____-side polygon capsid. - Bacteriophage; 20-sided True or False. Structurally, bacteriophages are similar to viruses that infect animals. - False. Bacteriophages have a distinct composition and structure. See image in notes - 1 - Capsid (or Head) 2 - Collar 3 - Tail (sheath) 4 - Base plate 5 - Tail fibers
Describe the main differences between lytic and temperate phages. - Lytic bacteriophages replicate within the host bacteria until it ruptures, whereas temporate (or lysogenic) phages primarily exist in a non-replicative state that does not kill the host cell. Lytic phages replicate all viral proteins needed for the assembly of new virus particles whereas lysogenic phage genomes are integrated into the host genome but production of viral proteins is suppressed. Based on the following image, would you expect the viral titer to be high or low? Why? Look in notes for image - Low. As turbidity is a function of the number of intact bacterial cells present in the media, the amount of virus contained within the above tube must be low. As the lytic cycle continues more and more bacterial cells will be destroyed, effectively clearing the media. Which of the following can be spread via airborne particles: A. Measles B. Mumps C. Rubella D. A and B E. All of the above - E. Measles, mumps and rubella can all be spread via airborne particles formed while coughing, sneezing, etc. True or False. A patient infected with Rubella is only considered infectious when the trademark rash is visible. - False. A patient infected with Rubella is infectious one week before and one week after the appearance of the rash. A patient diagnosed with German measles may additionally experience what disease? Select all that apply. A. Impetigo B. Conjunctivitis C. Rheumatic fever D. Influenza-like symptoms - B and D. A patient may experience a combination of symptoms such as fever, flu-like symptoms (influenza), cough, conjuctivitis, and a red blotchy skin rash. Which of the following diseases does a linear, single-stranded RNA virus cause?
