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A wide range of topics in molecular biology and microbiology, including the structure and function of proteins, lipids, nucleic acids, and carbohydrates, as well as the characteristics and roles of various cellular organelles and processes. It delves into the details of dna, rna, and protein synthesis, energy production, and the classification and identification of microorganisms. The document also explores various microscopy techniques, growth media, and the pathogenesis of infectious diseases caused by bacteria, viruses, and other microbes. With its comprehensive coverage of these fundamental concepts in the life sciences, this document could be a valuable resource for students and researchers in fields such as biology, biochemistry, microbiology, and biotechnology.
Typology: Exams
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True/False. A virus is considered a microorganism. - ✔✔False, Viruses are not living and as such are not considered microorganisms. Viruses can, however, be classified as microbes, a more general term that includes microorganisms and viruses. What is the smallest biological unit of life? - ✔✔A cell What are the four main types of macromolecules found in cells? - ✔✔Proteins, Lipids, Nucleic Acids, Carbohydrates Proteins are formed from various combinations of - ✔✔Amino acids There are how many known forms of amino acids - ✔✔twenty How many amino acids are classified as being essential amino acids? - ✔✔Nine Where can the two major types of nucleic acids be found in the cell? - ✔✔DNA, RNA. Found in the nucleus. What is the role of RNA? - ✔✔RNA , found in the nucleus is capable of leaving the nucleus. RNA is repsponsible for deciphering the hereditary information in DNA and uses it to synthesize proteins.
What is the role of DNA? - ✔✔DNA, found in the nucleus contains vast amount of hereditary inforamtion, responible for inhereitable characteristic os living organisms. Complete the following RNA strand, and indicate how many bonds are formed for each complementary pair: 3' GGUCAUCG 5'5' CC AGC 3' - ✔✔3' GGUCAUCG 5'5' CCAGUAGC 3'There are 2 bonds formed between A and U, and 3 bonds between G and C. The plasma membrane - ✔✔Restricts movement of materials in and out of the cell & Prevents essential nutrients from escaping How many carbon atoms are present in glucose? - ✔✔ 6 True of False: The genetic material within a prokaryotic cell is contained within a membrane- enclosed region. - ✔✔False Only eukaryotic cells contain its genetic material within a nucleus. True or False: Prokaryotic cells can be subdivided into Bacteria and Archaea. - ✔✔True True or False: Archaea is noted for its ability to survive under harsh conditions. Correct! - ✔✔True
Archaea can often be found in harsh conditions such as high salt levels, high acid conditions, high temperatures and even oxygen-poor conditions. Which of the following microorganisms are considered to be Eukarya? Select all that apply. - ✔✔Animalia, Plantae, Fungi, Protista Microorganisms classified as Plantae obtain most of their energy by converting [answer1] energy into [answer2] energy. - ✔✔1. Light (sunlight)
The function of the mitochondria is - ✔✔To produce energy (ATP) True or False. All multicellular microorganisms classified as Animalia are autotropic. - ✔✔False True or False: Metabolism is a controlled set of biochemical reactions that occur in living organisms in order to maintain life. - ✔✔True True or False: Enzymes slow down chemical reactions to conserve energy. - ✔✔False What is a cofactor? - ✔✔A cofactor is a small chemical component that assists an enzyme during the catalysis reactions. A cofactor is usually metal ions. Define catabolism - ✔✔Catabolism is the process of breaking down larger molecules into useful energy sources. In order to convert proteins into amino acids which metabolic process would be active? - ✔✔Catabolism would be active as proteins are made up of amino acids. Therefore the process described (proteins into amino acids) is the breakdown, or catabolism of protein. 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).
From what source do chemotrophs acquire energy? - ✔✔Chemotrophs acquire energy from preformed chemicals found in the environment. An organism that obtains its source of carbon from inorganic molecules such as carbon dioxide is referred to as a ____________? - ✔✔Autotroph This phosphorylation process occurs in the mitochondria of chemotropic eukaryotes. - ✔✔Oxidative phosphorylation The catabolism of a single molecule of glucose goes through what 3 distinct transitions? - ✔✔The breakdown of glucose goes through (1) Glycolysis then (2) Fermentation or Respiration and finally through (3) the electron transport chain (ETC). What is the most energetic transition in the catabolism of glucose? - ✔✔The electron transport chain yields 34 ATP while both glycolysis and fermentation (or respiration) each yield only 2 ATP. 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 are the main two roles of glucose- 6 - phosphate in the cell? - ✔✔Glucose- 6 - phosphate, also known as G6P (1) prevents glucose from diffusing out of the cell as well as (2) serves as the signal molecule to the cell that glycolysis is about to begin. True or False: During fermentation one means of eliminating pyruvate is by converting it into lactic acid. - ✔✔True Pyruvate can be converted into either lactic acid or ethanol and then eliminated from the cell. What is the primary byproduct of the TCA cycle? Select all that apply. - ✔✔NADH, FADH 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 cannot be used as alternative energy sources? Select all that apply. - ✔✔Nucleic acids For the catabolism of proteins and lipids, which of the following enzymes are used? Select all that apply. - ✔✔Proteases, Lipases True or False. The β-oxidation pathway catabolizes the fatty acid chains of lipids. - ✔✔True
Describe the relationship between chloroplasts and chlorophyll. - ✔✔Both chloroplasts and chlorophyll are associated with photosynthesis. Chloroplasts are the double membrane- enclosed organelles that contain the photosynthetic pigment chlorophyll. True or False: Chloroplasts are specific to algae and plants. - ✔✔True The process of carbon fixation begins with which of the following reactants: select all that apply. - ✔✔CO2, H2O, ATP, NADPH What is one of the main functions of light reactions? - ✔✔Similar to the electron transport chain, one of its main functions is to generate a proton concentration gradient to generate ATP. True or False: The Calvin cycle must occur in the absence of light. - ✔✔False, dark reactions do not actually require darkness in order to occur. How many turns (or repititions) of the Calvin Cycle are required to generate one molecule of glucose? - ✔✔ 6 [answer1]CO2 + [answer2]ATP + [answer3]NADPH + [answer4] H20 → C6H12O6 + [answer5]ADP + [answer6] NADP+ - ✔✔6, 18, 12, 12, ----> 18, 12 A micrometer is defined as: - ✔✔ 10 - 6
Resolution is a factor that influence your ability to see an object. Explain - ✔✔Resolution refers to the distance between two objects at which the objects still can be seen as separate. Poor or low resolution means two (or more) objects may appear as one. Contrast is a critical factor that influence your ability to see an object. Explain - ✔✔Contrast is the difference in light absorbance between two objects. Poor contrast gives a high background and makes the visualization of multiple objects difficult. Assuming a fixed ocular, identify the part of the microscope you would adjust to enhance the magnification of a sample. - ✔✔Objective What is the total magnification (relative to your eye) of a sample imaged with a 60x objective and a 10x eyepiece? Show your math. - ✔✔The total magnification is (objective x eyepiece)= Total magnification: 60 x 10 = 600x magnification True or False: A cell that is adherent, flat (thin), and unstained is easily identified using bright field microscopy. - ✔✔False Which of the following could be seen clearly by the unaided eye? - ✔✔Protozoa with diameter of 150 μm, Skin cell with diameter of 1500 μm
This type of microscope is best suited for visualizing GFP, RFP, and YFP proteins. - ✔✔Fluorescence This type of microscope uses a specialized condenser and objective to amplify the slight differences between cells and background. - ✔✔Phase-Contrast This type of microscope enhances contrast between specimen and background but does not permit the visualization of intracellular structures. - ✔✔Dark Field This type of microscope is capable of capturing images in multiple focal planes, rendering a specimen in 3-D. - ✔✔Confocal What does a SEM microscope show you? - ✔✔Scanning Electron Microscope (SEM). The above image shows the trademark 'shell' image (no subcellular organelles are visible) reminiscent of SEM. Only TEM is capable of visualizing subcellular substrucutres. Gram-Positive cells appear [answer1] in color due to a [answer2] peptidoglycan layer in the cell wall. - ✔✔1. Purple
True or False: Following the decolorization step of the Gram stain, Gram-Negative bacteria will appear colorless. - ✔✔True, Even together, the LPS and thin peptidoglycan layer are unable to retain the crystal violet dye during decolorization. True or False: If you wish to study the motility of an organism you cannot heat fix, but you can chemically fix the specimen. - ✔✔False Both heat and chemical fixation strategies will kill the cell, making motility observations impossible. You want to observe the size and shape of a cell. What is the easiest staining technique that you could perform? Name at least one dye you would use during this process. - ✔✔Simple stain. You could use any of the following: methylene blue, crystal violet, safranin or fuschin. You suspect a patient may have TB. Once a sample has been obtained, it is sent off to the lab for an acid-fast stain. If the patient were infected with TB, describe what you would expect to see on the stained slide. - ✔✔You would expect to see red cells (TB+) on a blue background (TB negative). True or False: If a patient is suspected of having malaria, a Giemsa stain would be an appropriate differential test to perform. - ✔✔True Giemsa stains are often used in the clinical setting to aid in the diagnosis of blood parasites.
What does the TEM microscope show? - ✔✔Transmission Electron Microscope (TEM). Even at 20nm resolution (inset image), subcellular substructures are still visible. A gram stain has been attempted on an unknown sample, and it was found to have a high degree of resistance to decolorization. Given this property, which stain should be attempted next? - ✔✔Acid-fast staining A fluorescence microscope shows - ✔✔Dark background and fluorescense bacteria (lime green) A slide stained with methylene blue simple stain to observe cellular morphology - ✔✔Bright field The gliding motility of a living cyanobacteria - ✔✔Phase contrast An unstained sample that cannot be visualized with bright field because microorganism absorbs very little light - ✔✔Dark field The expression level a protein of interest under experimental conditions in a cell - ✔✔Florescence Build a 3-dimensional image of a cell - ✔✔Confocal
True or False: Growth media is best suited for distinguishing between two similar species of bacteria. - ✔✔False Growth media is designed to simply support (and not restrict) microbial growth. A researcher is asked to determine if a sample contains Neisseria meningitides. Knowing Neisseria meningitides is slow growing and other foreign microbes may also be present in the culture, which type of media would be best suited? - ✔✔Selective media What are the requirements of a fastidious microbe? - ✔✔Fastidious microbes have complex growth requirements such that if absent it will not grow. Enriched medias thus contain these specific and essential nutrients required for the growth 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. What is agar used for in microbiology? - ✔✔Agar is used to create a solid, smooth surface on which microbes can grow. Blood agar is which type of medium? Select all that apply. - ✔✔Differential, Enriched Alpha hemolysis has... - ✔✔Incomplete Hemolitic activity
Beta Hemolysis has... - ✔✔Complete hemolitic activity Gamma Hemolysis has... - ✔✔No hemolitic activities Columbia CNA agar is used to isolate - ✔✔Gram-Positive 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. When e.coli is on a MacConkey agar plate, is a gram stain necessary to confirm if E.coli is gram- neg or gram-pos? - ✔✔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. In Eosin Methylene Blue (EMB) agar, what color indicates the presence of E. coli? - ✔✔Metallic Green
Which type of agar media is best suited to support the growth of Staphylococcus? - ✔✔Mannitol salt agar What is the process of spreading a bacterial culture onto a petri dish called? - ✔✔Plating In order to visual individual colonies of bacteria would you culture your sample in a liquid media or on a solid (agar) media? Why? - ✔✔Solid (agar) media. The primary advantage is that cells are held into place. When grown in a nutrient broth, bacterial cells can multiply but are free to move around in solution. When grown on agar within a petri dish the fixed in such as way as to form colonies. True or False: The visualization of colonies on a petri dish represents bacterial cells that have multiplied ~2-3 times. - ✔✔False True or False. The purpose of a quadrant streak is to produce individual colonies of a bacterial population. - ✔✔True To be considered a pure culture, the sample (1) can be traced back to a single cell and (2)__________? - ✔✔The culture must also be free from external contaminants. Simply put, a pure sample would never contain multiple bacterial species (ie) Strep and Staph. When performing a quadrant streak, the sample is spread across the plate in such as way as to form what? - ✔✔A dilution gradient is formed. The resulting gradient should always contain within it the growth of individual colonies.
In what phase of a dilution streak would you expect to find the highest concentration of bacteria, P2 or P4? - ✔✔P2 (Phase 2) would contain a higher concentration of bacteria than Phase 4 (P4). The phases rank (from highest to lowest), P1 > P2 > P3 > P4. 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. The number of phases (3 vs. 4) and/or the number of times a loop passes through a previous phase (once vs. multiple times) is acceptable provided what happens? - ✔✔Either deviation is acceptable in practice provided the resulting gradient contains within it the growth of individual colonies—if not, the experiment must be repeated. True or False. Pathogenic strains of bacteria tend to grow slower than normal non-pathogenic bacterial strains. - ✔✔False Pathogenic strains of bacteria tend to grow faster than non-pathogenic strains at 37°C, which is why 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? MSA agar LB media
MacConkey agar Columbia CNA agar - ✔✔LB media. All other options (A, C and D) are all forms of selective media, meaning they may potentially inhibit the growth of the unknown sample. The concept of treating all samples, whether known or unknown, as potentially hazardous (or pathogenic) materials is known as __________. - ✔✔Universal precautions List at least 3 observations a researcher would be sure to note while assessing an unknown microbial sample. - ✔✔Size, shape, color, chemical reactions, image of the sample, gram staining (neg or positve) 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. A facultative anaerobe is a microorganism capable of growth under what conditions? - ✔✔A facultative anaerobe is capable of growth under aerobic (with oxygen) and anaerobic (without oxygen) conditions. As Streptococcus is catalase negative would it thrive or die in the presence of peroxides? Why?
Streptococcus is most often streaked onto - ✔✔Blood agar True or False. The Lancefield groups are used to subdivide antigenic groups of gamma- hemolytic Streptococcus. - ✔✔False The Lancefield groupings are used to subdivide beta-hemolytic Strep. Greater than 90% of all human streptococcal infections belong to: - ✔✔Group A Rheumatic fever displays ______ hemolytic activity and occurs when _______ is left untreated.
Evasion - ✔✔Pathogen masks its own antigens to hide from the hosts immune system Entry - ✔✔utilization of a portal to gain access to host tissues Childhood skin disease near mouth/nose - ✔✔impetigo Infection of thin, transparent scleral tissue - ✔✔conjunctivitis Infection occurs at time of birth - ✔✔ophthalmia neonatorum Pus-filled lesions on skin or hair - ✔✔folliculitis Ruptured pustules; treated with Penicillin - ✔✔scalded-skin syndrome True or False. Staphylococcus is the only causative agent of conjunctivitis. - ✔✔False True or False. Tuberculosis is best identified by a Gram stain. - ✔✔False True or False. Although TB must be inhaled and reside in the lung in order to cause infection, TB can also spread to the brain, spine, and kidneys. - ✔✔True
TB can move systemically through the blood to infect other areas (brain, spine and kidney). However, when located outside of the lung, TB tends to be non-infectious. Identify the disease: 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. - ✔✔Hansen's disease, Leprosy True or False. Only directly ingesting the pre-formed clostridium toxin (neither the bacteria nor its spores) will cause disease in adults. - ✔✔False While visiting his grandparents, a 10-year-old child has green beans for dinner that were harvested from his grandparents' garden and canned the previous year. Severe illness sets in and the child is taken to the hospital. Botulism is suspected, but what form? - ✔✔Foodborne botulism. The child is too old (> 6 months) to be considered for infant botulism and wounds were not present. The green beans were likely improperly canned 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? - ✔✔Gas gangrene 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? - ✔✔Legionnaires. 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. Anthrax causes the skin to look - ✔✔burned and decayed of the flesh with a red ring around the wound Gonnorrhea is caused by: - ✔✔Diplococcic bacteria True or False. Chlyamida is an obligate parasite and as such can be grown on agar plates alone. - ✔✔False Gonorrhea - ✔✔Cardiac and neurological complications
Syphilis - ✔✔Paralysis, blindness and dementia Chlamydia - ✔✔Infertility and pelvic inflammatory disease. True or False. Because the genome is contained within an enclosed space (much like the nucleus of a cell), viruses are classified as eukaryotic. - ✔✔False Describe the two basic components of a virus. - ✔✔A virus has (1) genomic material comprised of either DNA or RNA and (2) a capsid, a membrane-like protective structure that contains the genetic material, similar to the nucleus of a eukaryotic cell. The ________ surrounds the capsid of some viruses. - ✔✔Envelope True or False. You would expect to see a viral envelope on a virus infecting a bacterial cell. - ✔✔False Rank the following viruses based on their size from largest to smallest: Orthomyxovirus Poliovirus Variolavirus - ✔✔1) Variolavirus
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. If a viral titer is cloudy... is it high or low - ✔✔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. Which viruses spread via airborne particles? - ✔✔Measles, mumps, rubella True or False. A patient infected with rubella is considered infectious one week before and after the appearance of the trademark rash. - ✔✔True A patient diagnosed with German measles may additionally experience what disease? - ✔✔Conjunctivitis, Influenza-like symptoms What disease displays as a secondary characteristic swelling of the testes/ovaries and pancreas? - ✔✔Mumps, causes primary swelling in the paratoid gland, testes and ovaries You go to visit a friend who has chickenpox. While visiting what are 2 things you will be sure to avoid so that you don't also become infected? - ✔✔(1) You would want to be sure to keep a distance especially if your friend is coughing or sneezing as chickenpox can be transmitted
through air-borne droplets (sneezing/coughs). (2) You would also be absolutely certain to avoid direct contact with the blisters of an infected individual. True or False. Someone who had chickenpox as a child is likely to develop shingles while in college, where the median age of college students is 18-22 years old. - ✔✔False True or False. Unlike chickenpox, the blisters that appear with shingles are localized and limited to small areas. - ✔✔True. While chickenpox blisters often cover the entire body, the blisters associated with shingles are localized and limited to small areas. A person who has neither previously had chickenpox nor been administered the VZV vaccine is exposed to someone with an active VZV (shingles) outbreak and becomes infected. Explain why (or why not) the person will only develop shingles. - ✔✔The infected individual will not develop shingles, but will develop chickenpox. Unvaccinated and unexposed individuals must first develop chickenpox, as shingles is the reactivation of the dormant VZV virus from the chickenpox infection. What linear, double-stranded, enveloped DNA virus is the first virus (as of Oct. 26, 1977) to be officially declared eradicated? - ✔✔Smallpox What small (~30nm) single-stranded, non-enveloped RNA virus causes temporary or permanent paralysis by infiltrating (infecting) motor neurons within the spinal cord, brain stem, or motor cortex? - ✔✔Polop
By whom and where was the first polio vaccine developed? - ✔✔Jonas Salk, University of Pittsburgh 1995 Which subtype of Influenza is the most virulent? - ✔✔Influenza A A drug company is trying to develop a new drug that will inhibit viral entry of Influenza. Would the drug company target hemagglutinin proteins or neuraminidase proteins? Why? - ✔✔Hemagglutinin (HA) proteins would be targets as they are directly involved in viral attachment and entry into the host cell. Explain why the flu shot given each year may not be 100% effective at preventing the flu? - ✔✔It is possible to receive a flu vaccine and yet (unfortunately) still get the flu in the same season if you are exposed to a viral strain that was not included in the vaccine. There are a large number of variants and the flu vaccine is unable to vaccinate against all subtypes. True or False. The viral capsid of HIV is dumbbell shaped and contains ~2,000 copies of the viral protein p24. - ✔✔False The HIV surface glycoprotein gp41 binds what host cellular receptor? - ✔✔CXCR4 HIV gp41 binds to the receptor CXCR4 An individual infected with HIV is placed on anti-retroviral medication. What is the general purpose of this medication? - ✔✔As the name suggests, anti-retrovirals are intended to inhibit (anti) the life cycle of retroviruses (retro).