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CURRENTLY TESTING SOLUTIONS OF ASU MIC 205 PENTON
EXAM 1 QUESTIONS WITH ACTUAL CORRECT DETAILED
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What is a simple stain used for? To increase contrast and visualize the basic shape and arrangement of cells. How does a simple stain work? By applying a single dye (like crystal violet or methylene blue) to the bacterial smear, causing all cells to take on the same color. What is a limitation of simple staining? It does not distinguish between different types of cells. What is a common example of a type of stain used in the differential staining technique? Gram stain What does the Gram stain differentiate between? Gram-positive and Gram-negative bacteria What is the purpose of a differential stain? To differentiate between different types of bacteria or cellular structures based on their characteristics How do cells appear differently after undergoing a differential stain? Cells will take on different colors based on their properties, allowing for identification and classification what does a gram stain detect detects the pretense of bacteria and helps to differentiate between gram + and gram - based on cell wall structure
How does a gran stain differentiate bacterial cells they get dyed a different color both will be purple at first then they add iodine allowing color to stick to cell then add alcohol or acetone which shows what they will be what color is a gram positive bacteria The thick peptidoglycan layer retains the crystal violet-iodine complex, so they remain purple. what color is gram negative bacteria pink, they don't retain the color so they counterstain with safranin and it absorbs the pink color. What is the cell wall structure of Gram-positive bacteria? Thick Peptidoglycan Layer What component of Gram-positive bacteria's cell wall is involved in maintenance and protection? Teichoic Acids How do Gram-positive bacteria appear after the Gram staining process? Purple under a microscope Are Gram-positive bacteria generally more or less susceptible to antibiotics that target the peptidoglycan layer? More susceptible What type of toxins do Gram-positive bacteria typically produce? Exotoxins Name two examples of Gram-positive bacteria. Staphylococcus aureus, Streptococcus pneumoniae What are the components of the cell wall structure in Gram-negative bacteria? Thin Peptidoglycan Layer, Outer Membrane How do Gram-negative bacteria stain in the Gram staining process? Do not retain crystal violet, appear pink after counterstaining with safranin Why are Gram-negative bacteria often more resistant to antibiotics? Due to protective outer membrane, efflux pumps, and porins that limit drug entry What can act as endotoxins in Gram-negative bacteria? Lipopolysaccharides in the outer membrane Provide examples of Gram-negative bacteria.
Malachite green what color do Vegative cells appear after Schaeffer Fulton stain Pink from safranin What has to be done tothe proteins in the cell membrane in order to drive the primary stain into the endospore? To drive the primary stain (malachite green) into the endospore during the Schaeffer-Fulton staining procedure, the proteins in the cell membrane of the endospore must be denatured. This is accomplished by applying heat during the staining process. What is an endospore? a dormant, tough, and temporarily non-reproductive structure produced by certain bacteria. Why do bacteria make endospores to survive in unfavorable environments they can form endospores to protect their genetic material and essential cellular components until conditions improve. ex. depleted nutrients, extreme temps What bacterial group discussed in class is medically important and form endospores?How does this relate to C. diff? Bacteria that form endospores such as bacillus and clostridia Is relevant medically because its resistant to treatment and can cause death It relates to C diff because they both are both G+, have endospores that are hard to treat and have the same symptoms What does it mean for a bacterial growth medium to be selective? A selective growth medium is designed to inhibit the growth of certain types of bacteria while allowing others to grow This is achieved through the addition of specific substances, such as antibiotics or specific nutrients, that favor the growth of target organisms What does it mean for a bacterial growth medium to be differential? allows multiple types of bacteria to grow but contains specific indicators that help distinguish between them based on their biochemical characteristics. These indicators can change color or produce a precipitate in response to specific metabolic activities. Understand the selective aspects of MacConkey's agar (MAC). effectively isolate Gram-negative bacteria by inhibiting Gram-positive bacteria through the inclusion of bile salts and crystal violet, facilitating further analysis and identification of clinically relevant pathogens Understand the differential aspects of MacConkeys agar (MAC)
enable the identification and differentiation of lactose fermenting and non-fermenting Gram-negative bacteria What information does MAC provide about bacteria growing on this medium? Lac+ produce lactic acid, lowers the pH, changing the colonies to pink (due to a pH indicator-neutral red)Lac - do not ferment lactose, no lactic acid produced, white What makes Mannitol Salt agar (MSA) selective? MSA contains a high concentration of salt (7.5% sodium chloride), inhibiting the growth of most bacteria except halophilic organisms like Staphylococci. How does Mannitol Salt agar (MSA) function differentially? MSA differentiates between mannitol fermenters and non-fermenters based on color changes in the medium, aiding in identifying pathogenic Staphylococcus species. What information does MSA provide about bacteria growing on this medium? If organism can ferment mannitol, acid produced turns the phenol red to yellow. What specific bacteria can be identified in Mannitol salt agar (how are they clinically important)? GRAM +, Staphylococcus aureus What type of clinical samples is plated on Blood agar (BAP)? Not used selectively Used to grow a variety of bacteria and then be able to tell them apart by how they react to the blood in the plate What broad type ofbacteria are we looking for from a sample plated on BAP? looking for bacteria that can perform hemolysis and the lysis of red blood cells; differentiate STREP Beta: they lyse (break down release contents) red blood cells, leading to a clear zone around the colonies on blood agar. Alpha these bacteria partially lyse (break down release contents) red blood cells, resulting in a greenish discoloration around the colonies due to the reduction of hemoglobin to methemoglobin. Gamma These bacteria do not lyse red blood cells and do not affect the blood agar. How would Beta, alpha, and gamma appear on bloodagar? Beta: A clear zone (beta hemolysis) around the colonies. Alpha: A greenish or brownish zone (alpha hemolysis) around the colonies.
Conjugation involves the direct transfer of DNA between two bacteria through a physical connection known as a pilus. How does conjugation occur between bacteria? A donor bacterium with a conjugative plasmid forms a pilus to connect to a recipient bacterium. The plasmid is transferred through the pilus into the recipient cell. What happens after DNA transfer in bacterial conjugation? Both cells can then replicate the plasmid, allowing the recipient to gain new genetic traits. Can you provide an example of conjugation in bacteria? An example is the transfer of plasmids carrying antibiotic resistance genes between Escherichia coli cells. What is the lytic cycle of a bacteriophage? Definition: The lytic cycle results in the destruction of the host cell, leading to the release of new phage particles. What happens during the attachment stage of the lytic cycle? The phage attaches to the bacterial cell surface. What occurs during the penetration stage of the lytic cycle? The phage injects its DNA into the host cell. What is the biosynthesis stage in the lytic cycle? The host's cellular machinery is hijacked to produce phage components (DNA and proteins). What happens during the assembly stage of the lytic cycle? New phage particles are assembled within the host cell. What is the lysis stage in the lytic cycle? The host cell bursts (lyses), releasing the newly formed phages to infect other cells. What is the outcome of the lytic cycle? The host cell is killed, and multiple new phage particles are produced. What is the first step of the lysogenic cycle? Attachment: The phage attaches to the bacterial cell surface. What happens during the integration step of the lysogenic cycle? Integration: The phage DNA integrates into the bacterial chromosome, becoming a prophage. What is the outcome of the lysogenic cycle for the host cell?
Outcome: The host cell survives and replicates the phage DNA along with its own, potentially spreading the phage genes without immediate destruction of the host. When does the induction step occur in the lysogenic cycle? Induction (optional): Under certain conditions (e.g., stress), the prophage can be excised from the bacterial genome and enter the lytic cycle. what are the two basic types of cells Prokaryotic and Eukaryotic What are the characteristics of prokaryotic cells? No nucleous circular DNA rigid cell wall asexual diverse metabolism What are the characteristics of eukaryotic cells? True nucleus Has many membrane organelles size: 10 to 100 micrometers in diameter Cell Wall: plant cells and fungi, have a cell wall Reproduction: asexually and sexually what does the 16sRNA encode for encodes for ribosomes It serves as a biomarker for life , particularly in identifying and classifying bacteria. Why is the 16S rRNAgene chosen as an 'identifying characteristic', the barcode for life? "barcode for life" because it's 1. universal: present in all prokaryotic organisms (bacteria and archaea) allowing for widespread identification. 2. essential for life:. 3. variable & constant regions Key characteristics of Archaea single celled, no nucleus
Glucose enters cells via specific transporter proteins (GLUT transporters) because glucose is too large and polar to pass through the membrane directly. What is active transport? A method that requires energy (usually from ATP) to move molecules against their concentration gradient, from an area of lower concentration to an area of higher concentration. What is the role of the sodium-potassium pump in active transport? It actively transports sodium ions (Na⁺) out of the cell and potassium ions (K⁺) into the cell against their concentration gradients, using ATP for energy. what are the 2 types of active transport endocytosis and exocytosis Endocytosis and Exocytosis: In endocytosis, the cell membrane engulfs material to bring it inside the cell, while exocytosis involves vesicles fusing with the membrane to release materials outside the cell. Endocytosis example Phagocytosis, where immune cells like macrophages engulf bacteria or debris by wrapping the cell membrane around them and forming a vesicle. Exocytosis Neurotransmitters are released from nerve cells into the synaptic cleft when vesicles containing these signaling molecules fuse with the plasma membrane. why do bacteria have to move molecules across the membrane Nutrient uptake, waste removal, signal reception, Homeostasis, Energy production What are the different transport proteins? Channel Proteins, Carrier Proteins :, Pump Proteins, Symporters, Antiporters How do channel proteins operate? They form water-filled pores that allow specific ions or small molecules to pass through. What determines whether channel proteins are open or closed? They can be open all the time or gated, it opens or closes when it gets a signal like a physical pressure or electrical voltage What is the function of open channel proteins? When open, they allow rapid movement of substances down their concentration gradient through facilitated diffusion. How do carrier proteins operate?
Carrier proteins bind to specific molecules then they change shape to fit through the channel and gets dropped off inside What happens to carrier proteins after binding a molecule? The protein changes shape (conformational change), allowing the molecule to be released on the other side of the membrane. What are the two types of processes involving carrier proteins? The process can be passive (facilitated diffusion) or active (requiring energy). How do pump proteins operate? Pump proteins actively transport ions or molecules against their concentration gradient. What provides energy for pump proteins to function? Pump proteins use energy from ATP hydrolysis to transport ions or molecules. Can you give an example of a pump protein? An example is the sodium-potassium pump, which moves Na⁺ out and K⁺ in. how do Symporters operate type of carrier protein (for example you drive 2 different friends (glucose, and sodium) to the store. It takes 2 different things at once to the same place at the cell time (into the cell) how do Antiporters: operate Type of carrier protein (for example its like a se saw when one friend goes up the other goes down against their concentration gradient) Uses energy to keep everything balanced What is the main function of the plasma membrane? The plasma membrane regulates the movement of substances into and out of the cell. How does the plasma membrane maintain homeostasis? by controlling what enters and exits the cell, using both passive and active transport. How do bacteria reproduce? How is the cytoskeleton involved in this process? Bacteria reproduce primarily through binary fission, where one cell divides into two identical cells. The cytoskeleton aids in this process by helping to organize the cell's structure, ensuring proper division and separation of genetic material. What is the implication of bacteria not having a nucleus while eukaryotes do, in terms of transcription and translation? Bacteria don't have a nucleus, so they can make RNA and proteins right next to each other in the cytoplasm at the same time
Staphylococcus is typically spherical (cocci), forms clusters, and is catalase-positive. Streptococcus is also spherical but forms chains and is catalase-negative. Their arrangements influence pathogenicity and identification. What is the role of peptidoglycan and composition? Peptidoglycan provides structural support to bacterial cell walls, preventing lysis. It consists of a polymer of sugars (Nag and nam). What are the two types of glycocalyxes? Capsules and slime layers What is the advantage of capsules in glycocalyxes? Capsules help bacteria evade the immune system by masking antigens They cover the bacteria serving as a protective layer to the bacteria What is the advantage of slime layers in glycocalyxes? Slime layers aid in adhesion and biofilm formation, enhancing survival and resistance to antibiotics What are the characteristics of a microbial flagella? long, whip-like structures made of proteins that enable motility by rotating or waving, allowing bacteria to move toward or away from stimuli in their environment. How does the flagella move and howdo the bacteria move? Compare to flagella in eukaryotes. Bacterial Flagella : Rotate like a propeller, using proton gradients for energy, allowing bacteria to swim in liquid environments. Eukaryotic Flagella : Move in a wave-like manner, powered by ATP, found in cells like sperm. What is an endoflagella? What movement characteristics are induced by an endoflagella? between the cell membrane and outer membrane endoflagella are internal flagella that help certain bacteria move in a corkscrew fashion, making it easier for them to move through dense environments. How does the shape of a bacteria possibly help in infection? The shape of bacteria, such as rods or spirals, can enhance their ability to invade host tissues and evade immune responses. For example, spiral-shaped bacteria can burrow into tissues more effectively. What are pili used for in prokaryotic cells? Pili are used for attachment and genetic exchange. What is the function of fimbriae in prokaryotic cells?
Fimbriae are used for adhesion. How do surface appendages enhance bacterial colonization and biofilm formation? Surface appendages aid in infection and survival. What advantage do endospores provide to bacteria? Endospores provide resistance to extreme conditions, including heat, desiccation, and chemicals. This allows bacteria to survive harsh environments and ensures persistence during unfavorable conditions. What are the different arrangements of prokaryotic cells? Clusters (staphylococci), chains (streptococci) what are the different shapes of prokaryotic cells. cocci (spherical), bacilli (rod-shaped), or spirilla (spiral-shaped) How do different shapes and arrangements of prokaryotic cells affect their identification and pathogenicity? Shapes and arrangements influence how prokaryotic cells are identified and their ability to cause disease. (by looking at the shape/ arrangements we can be able to tell that a chain or cluster might be either staph or strep) How are endospores stained? What is a capsule stain? Endospores are typically stained using the Schaeffer-Fulton method, which involves malachite green and safranin. A capsule stain uses a negative stain to visualize the capsule surrounding the bacterial cell, highlighting its presence. What is the role of Pili gene transfer? What do they transfer? How do Fimbriae differ from pili? Pili facilitate genetic exchange (conjugation) between bacteria by forming a bridge for DNA transfer. Fimbriae primarily assist in adhesion to surfaces, not in genetic transfer. How does the genomic DNA differ from plasmid DNA? Genomic DNA is the main circular chromosome containing essential genes, while plasmid DNA consists of smaller, circular DNA fragments that carry additional genes, often for antibiotic resistance or metabolism. What is the difference between genomic DNA and plasmid DNA in terms of competition? Genomic DNA is crucial for survival and reproduction, while plasmids can confer competitive advantages, such as antibiotic resistance. Bacteria with beneficial plasmids can outcompete those without them in stressful environments What is a biofilm? How do bacterial external structures aid in its development?
N-acetylglucosamine (Nag) and N-acetylmuramic acid (Nam) are the two main sugar components of peptidoglycan, forming the backbone structure of bacterial cell walls. What is a murein protein, where is it found and in what type of bacteria? Murein proteins are associated with the peptidoglycan layer, providing structural support. They are primarily found in Gram-positive bacteria. What is lipotechoic acid, who has it, where is it found? Lipotechoic acid is found in Gram-positive bacteria, embedded in their cell wall. It plays a role in cell wall integrity and can trigger immune responses. Where are LPS found? In what type of bacteria? What are the different portions and their roles? LPS are found in the outer membrane of Gram-negative bacteria. It consists of three parts: lipid A (toxic effects), a core oligosaccharide (structural stability), and an O antigen (immune evasion). How do bacteria store nutrients? Bacteria store nutrients in granules or as inclusions, which can contain carbohydrates, lipids, or polyphosphate, providing energy reserves during nutrient scarcity. What is the role of fimbriae in urinary tract infections? Fimbriae enable bacteria, such as E. coli, to adhere to the urinary tract lining, facilitating colonization and contributing to the development of urinary tract infections. What is the role of the capsule? Capsules protect bacteria from phagocytosis, masking antigens to evade the immune system. They also help in adhesion and biofilm formation, enhancing bacterial survival. Explain how each bacterial external structure can aid in the development of infection. Capsule : Evades immune response. Fimbriae : Facilitates adherence to host tissues. Flagella : Promotes movement toward infection sites. Pili : Allows for genetic exchange and attachment. What is the phospholipid bilayer? The phospholipid bilayer is the fundamental structure of the plasma membrane, consisting of two layers of phospholipids with hydrophilic heads facing outward and hydrophobic tails inward, creating a semi- permeable barrier. What is the composition of the gram - lipopolysaccharide (LPS)? LPS is composed of lipid A, a core oligosaccharide, and O antigen. This structure is crucial for the integrity of the outer membrane and plays a role in immune system evasion.
Why do jam and jellies prevent the growth of bacteria? Jam and jellies have high sugar concentrations, creating a hypertonic environment that draws water out of bacterial cells, inhibiting their growth and reproduction. microbiota. the term for the microbes that are normally present in and on the human body; usually beneficial Colonization refers to the ability of the microbe to stay attached to the body surface and replicate. Parasites are microbes that cause harm-inducing infections. • Ectoparasites
- Endoparasites pathogen any bacterium, virus, fungus, protozoan, or worm (helminth) that causes disease in humans. Pathogenicity ability of the organism to cause disease infection occurs when a pathogen or parasite enters and begins to grow on the host. Disease occurs when the patient develops symptoms. acute infection symptoms develop and resolve rapidly.
- The common cold chronic infection involves symptoms that develop gradually and resolve slowly.
- Tuberculosis host range refers to the animals a pathogen can infect and produce disease in. Narrow Salmonella enterica serovar Typhi infects humans only. • Broad
( Lyme disease :) Ebola Virus does cause disease in the animal host and also in humans Fecal-oral Portal is the mucosa of the GI tract. Skin Portal is the skin epithelium. Respiratory : Portal is the mucosa of the respiratory tract. Urogenital : Portal is the mucosa of the genital and urinary tracts. Parenteral Portal is through breaks in the skin. Host genetic makeup host receptors to which bacteria and viruses bind Nutrition and exercise good nutrition and moderate exercise enhances the immune system. Clostridium botulinum
- the name of the organism = Clostridium botulinum- the "hallmark" of the disease = extremely lethal neurotoxin, poisoning NOT an infection --> so NO fever- the treatment = hospitalization, ventilator assist, trivalent antitoxin (ABE) AND antibiotics, and physical therapy for strength recovery.Adults receive antibiotics and ABE, while infants only receive ABE.- What causes the disease? = foodborne (canned goods) ingestion of spores, when infants eat honey or corn syrup and consume spores, through wounds (drug addicts reusing needles) - What is the disease progression? = in adults, it is rapidly fatal food poisoning and sudden respiratory paralysis. in infants, it is "floppy baby syndrome" so difficulty swallowing and muscle weakness. Symptoms can begin anywhere from 6 hours - 10 days depending on how the poisoning was brought on (food vs. wound)-
Does travel history, food consumption, social factors play a role in diagnosing the disease? = yes, it is prevalent in the western states (especially Alaska-improper food handling, and California- heroine) and can be ingested through food.- Does age play a role? = yes. both adults and infants can get this but they show different symptoms. Chlostridium tetani
- the name of the organism = Clostridium tetani- the "hallmark" of the disease = severe muscle spasms, lockjaw, risus sardonicus (smiling thing)- the treatment = antitoxin TIG (tetanus immunoglobulin), Penicillin G, muscle relaxers, and diazepams (anti-anxiety meds)- What causes the disease? = puncture wound from rusty nail exotoxin --> tetanospasmin What is the disease progression? = takes 8 days for symptoms to occur- Does travel history, food consumption, social factors play a role in diagnosing the disease? = no, just needs to have had a puncture wound from a rusty nail- Does age play a role? = no gasgangrene the name of the organism = Clostridium perfringens- the "hallmark" of the disease = fatal unless treated very early, causes cellulitis (moist, spongy, crackling skin due to pockets of gas). test --> crackling skin (rice krispie sound) & fingerprint test; if you push on them and the depression stays, it is an indication of this infection- the treatment = amputation of affected area, hyperbarics, debridement (removal of dead tissue), and antibiotics (Zosyn [G+], Gentamycin [G-], Vancomycin [MRSA]). hyperbarics help bc it forces oxygen in the muscle, killing the anaerobic bacteria causing the infection- What causes the disease? = due to wounds. often in obese or diabetic ppl. also seen in men's scrotums- What is the disease progression? = 6 to 48 hours after initial infection- Does travel history, food consumption, social factors play a role in diagnosing the disease? = yes, travel history may explain where and how the infection was picked up- Does age play a role? = no C. Diff
- the name of the organism = Clostridium difficile- the "hallmark" of the disease = red, inflamed mucosa, white exudates in colon (toxin B) and severe diarrhea (toxin A)- the treatment = metronidazole and vancomycin through IV for bloodstream absorption. alternative method: fecal transplant
