Microbiology Exam #1
Obligate aerobes and anaerobes
Obligate Aerobes = require oxygen for growth / Obligate Anaerobes = cannot survive in the presence of oxygen
Case Study 1 (isolated patient with C. Diff.)
PPE should be worn, constant hand washing, educate family on where the pathogen comes from and how to properly wash hands, bring in psychologist to evaluate the mental health of isolated patient
Differential
contains ingredients that differentiate between different organisms
Saturated V unsaturated fatty acids
Saturated = fatty acid containing all hydrogens attached to a carbon / Unsaturated = fatty acid containing loss of hydrogens due to a double bond with carbon
Identify a type of monosaccharide and polysaccharides
Monosaccharides = glucose, fructose / Polysaccharides = starch
Monosaccharides V Polysaccharides
Monosaccharides = one sugar / Polysaccharides = multiple sugars, 3 or more monosaccharides bound together
Define psychrophiles, mesophiles, and thermophiles
Psychrophiles = grow at cold temperatures / Mesophiles = grow at moderate temperatures / Thermophiles = grow at high temperatures
Identify the process as which bacteria talk
Quorum Sensing allows bacteria to communicate with chemical signals (autoinducers)
Radiation as a target
Radiation targets nucleic acids but disrupting genes
Importance of the lysosome
Uses its enzyme, lysozyme, to destroy pathogens. Special enzymes are produced so that lysosomes do not destroy materials of endocytosis.
mRNA
carries genetic information to site of the ribosome
Identify opportunistic pathogens
Normally harmless pathogens cause infection from normal flora when a host has increased susceptibility (compromised immunity). Common example is dental infections
Identify hospital acquired pathogens
Nosocomial infections = MRSA, Candida albicans, Pseudomonas aeruginosa, E. coli
Identify the process of DNA replication
Requirements: an ample supply of each of the 4 nucleotides and a primer called the template junction. 1. Topoisomerase 2. Helicase at the replication fork 3. Leading strand - replicated via DNA Polymerase, adds nucleotides at its 3' end, moves towards the fork 4. Lagging strand - DNA polymerase cannot read in the direction moving away from the fork so it uses okazaki fragments, the primer (template junction) is laid down so the DNA polymerase then knows where to start adding a set of bases 5. DNA ligase - links together bases for lagging strand
Explain and identify the different types of flagella arrangements
Monotrichouse = one at the end of the cell Peritrichous = surround entire cell
Know the two sugars that make up the bacterial peptidoglycan
NAG and NAM are the sugars that make up bacterial peptidoglycan
How treatment of TB works
Treatment of TB is a combination of isoniazid, ethambutol, and rifampin. Combinations of these drugs lower the chance for resistance. They inhibit the incorporation of mycolic acid into the cell wall
Identify how ATP loses phosphates
ATP loses its phosphate through hydrolysis. This process releases energy and turns the ATP into ADP.
Ionic bonds are transfers of electrons between which types of elements?
Ionic Bonds transfer electrons between a metal and a nonmetal
Carbapenems are used against what type of organisms
Used against Pseudomonas species
tRNA
brings amino acids to the ribosome in 3 base pair sequences that bind to mRNA to build proteins
Repressors
involved in negative regulation, turning off genes, conserving energy
Activators
involved in positive regulation
Rifampin
only rifamycin in use currently, Resistance develops rapidly if it is used alone
Which organisms rotate via axial filaments
spirochetes
Topoisomerase
unwinds the supercoils "relaxes"
Conjugation in GN
use pili to transfer plasmids from cell to cell
Iodine
used as disinfectant and ticniture (iodine settles within organs)
Beta hemolysis
wide zone clearing, S. pyogenes
Three-Nucleotide Insertion/Deletion
a codon is inserted or deleted, results in a shift in protein sequence but the protein will still most likely function, silent
Peroxide
a common antiseptic, bacterial catalase breaks it own but the amount of peroxide sed overwhelms the amount of catalase produced by bacteria
Cidal
an agent that kills
Thayer Martin Agar
enriched and selective, selects for fastidious organisms such as N. gonorrhoeae, used in patient samples that contain a large number of normal flora like te genital tract (almost all STD)
Aerotolerant
it can grow in the presence of oxygen, but it does not use oxygen in metabolic processes
rRNA
make up the ribosomes
Gamma hemolysis
no clearing, S. salivarius
Wild Type
no mutations
Silent mutations
no phenotypic effect although the pairing may be incorrect
Alpha hemolysis
partial clearing, S. pneumoniae, S. mitis
Sterilization
removal of all microbes (does not destroy prions)
Degreming
removal of microbes by mechanical means (radiation, steam, machine use)
Helicase
separates and unwinds the strands "unzips"
Conjugation in GP
stick to each other (adhesions) because they don't have pili, they transfer genes across cell membranes through type IV secretion system
Transformation
takes in genes from outside the cell via the pili to combined with the host cells DNA, involves naked DNA, encodes for different virulence factors
Transduction
transfer of genetic material between cells, uses a bacterial virus (phage) for transfer, common in gp and gn
Role of the DNA polymerase
DNA polymerase is an enzyme that replicates the strand of DNA during replication starting at the primer (template junction), it works quickly and it is very accurate. The newly synthesized strands are proofread
Base Excision
DNA repairs itself - removes damaged bases, DNA polymerase fills in the gaps, DNA ligase repairs the break in the strand
Nucleotide Excision Repair
DNA repairs itself - removes whole piece of damaged DNA, DNA polymerase fills in the gaps, DNA logare repairs the strand
What is mycolic acid
Mycolic acid is a waxy lipid substance within the gram positive cell wall that cannot stain with dyes. Makes mycobacterium species resistant to environmental stress, antibiotics, and host defenses.
Identify how flagella move and how its attached to the cell membrane
The flagella is attached to the cell membrane via its basal body. They move by spinning around their axis like a corkscrew. The flagels attaches to the cell membrane and extends way beyond the cell wall
Pyrimidines
Thymine and Cytosine, smaller
Surfactants are used to target which cell structure in bacteria and viruses
Surfactants target the phospholipid bilayer
Explain why tuberculosis affects minorities
Home countries have more dense populations and confined/unsanitary living conditions that spread TB. minorities is associated with decreased access to healthcare and vaccines
Identify and explain the components of the plasma membrane
Hydrophilic heads → phosphates Hydrophobic tails → fatty acid chains
Identify how sugars are cross linked
NAG and NAM are layered to create a strong cell wall component → enzymes link sugars to the lipid portion of the plasma membrane → the layers of cross linked sugars create peptidoglycan
Base-Pair Deleting
base is deleting, results in missense
Blood Agar
differential and enriched, determines types of hemolysis
Disinfectant
associated with inanimate objects
Chlorine
cleans drinking water and kidney dialysis equipment
Soaps
composed of an ionic bond, a hydrophilic head, and a hydrophobic tail, good for degerming but not sanitization
*Identify NAG AND NAM
N-acetylglucosamine and N-acetylmuramic acid
Static
an agent that inhibits growth, numbers do not multiple in a bacteriostatic environment but organisms are not dead
Purines
Adenine and Guanine, larger
Explain electronegativity. Identify how electronegativity increases within the periodic table
Electronegativity = an atom's tendency to steal electrons from another atom, more electronegative atoms steal more electrons. Electronegativity increases as you go up and to the right of the periodic table
Glycopeptide antibiotics identify, and what organisms are killed
Derived from Streptomyces organism (vancomycin and teicoplanin), kill staph aureus
A-
T (U if its RNA)
Identify the smallest microorganism
Virus is the smallest microorganism
Nonsense mutations
early termination via stop codon
Identify the goal of pathogens
- Get in - Stay in (evade defenses) - Reproduce - Spread
Issues with peptide antibiotics
Harm our own cells and DNA synthesis
C-
G
DNA connects in what prime to what prime
Connects in the 5' to 3' direction
Types of disinfectants
Heat, alcohol, UV light (chemical and physical agents)
Microaerophilic
requires only a low level of oxygen for growth
Why cell walls are good targets for antibiotics
Because eukaryotes lack peptidoglycan
Role of the promoter
The promoter is where RNA polymerase binds to DNA sequence and produces a bubble around the DNA during transcription. It is an indicator of where to start the process of transcription (DNA to RNA)
EMB Agar
differential to lactose and selective to dye inhibition and precipitation at acidic pH, lactose fermenters show blue/black (E. coli), non-fermenters show colorless or light purple (Salmonella, Shigella), E coli must be differential from lactose because both are found in the gut (produces metallic green sheen)
Sanitization
disinfection of places of things uses by the public to meet public health standards
Ozone
electrically excited oxygen makes O2, this causes oxygen to react with all covalent bonds which destroy all microorganisms, organism resistance
Case Study 2 (Viral pharyngitis suspected because adults rarely get strep)
pathology with have to use a specific growth media (blood agar) to identity the culture that was taken, group A Streptococcus pyogenes came up as positive despite a negative rapid test because the rapid testing is not fully accurate
Missense mutations
results in the wrong protein because base pair is incorrect
Base-Pair Insertion
base is inserted, results in immediate nonsense
Hydro-meteorological disasters
Floods, storms, tornadoes, hurricanes
Identify the difference between staph and strep on a microscope slide
Staph = clusters / Strep = chains
Aseptic
an environment or procedure free from contamination
Structure of DNA
A double stranded, helical structure, made up of 4 bases, runs 3' → 5' and 5' → 3'. Antiparallel because of the joining of the nucleotide bases
Explain phagocytosis and the importance
1. Detection of target material on surface 2. Activation of phagocytosis using the phagocytic cup 3. Formation of phagosome (internalization of substrate) 4. Maturation of phagosome Engulfment of pathogens
P site, A site, E site role
A --> P --> E, (exception for when tRNA brings the start codon to the P site at the beginning), A site becomes open for the next tRNA after shifting down
Why microbiology is relevant to healthcare
Advances in public health awareness lessen the effect of infections, Health care professionals need to understand how pathogens cause disease
*Identify the importance of covalent bonds as it relates to major biological molecules
All major macromolecules are made up of covalent bonds
Identify agents of bioterrorism
Anthrax, botulism, plague, smallpox, tularemia, hemorrhagic fevers, ricin toxin ... use of a microorganisms to harm or kill living things
How penicillins work against NAG and NAM and what organisms are good targets
B-lactam ring binds to the Penicillin-binding proteins in the cell wall. Penicillin prevents the formation of an intact cell wall. Works against --> streptococco (including streptococcus pneumoniae), Listeria, Neisseria gonorrhoeae, Clostridium, Peptococcus, and Peptostreptococcus
Identify the gram stain procedure with correct steps
Apply one drop of crystal violet (20 secs), wash with water --> Apply iodine (a mordant) (20 secs), wash with water (allows the dye to be permanent) --> Alcohol wash (decolorization), wash with water (destroys the outer membrane of gram negative bacteria, washes the violet out of the cell) --> Apply safranin (counterstain), wash with water (stains gram negative red since the outer membrane is destroyed from alcohol)
*Identify proper cellular organization
Atoms < molecules < organelles < cell < tissue < organ < organ system < organism
Identify a dehydration synthesis and hydrolysis reaction
Dehydration Synthesis = the removal of water to create larger bonds, building proteins / Hydrolysis = the addition of water to create smaller bonds, breaking down sugars
*Identify the understanding of biofilms
Bacteria working together to produce sugars in the form of a film in order to adhere and reproduce
The main component of penicillins
Beta-lactam rings, all derivatives have it
Biofilms are associated with
Biofilms are an issue for medical devices such as pacemakers and catheters
Sulfa drugs and targets
Block a step in the folic acid metabolism, Sulfamethoxazole combined with trimethoprim treat UTIs. Used for burn patients Sulfa drugs have selective toxicity
*Identify structures: carbohydrates, nucleic acids, proteins (in 4 stages), and fats
Carbohydrates = hydroxyl group / monosaccharides Nucleic Acids = phosphate group / nitrogenous bases (A-T, C-G) Proteins = amino group and carboxyl group / amino acids Primary: order of amino acids Secondary: helixed and sheets of polymer folding on itself at hydrogen bonds Tertiary: additional bonding to the secondary occurs Quaternary: multiple proteins bind together to form a unit with a unique structure Fats = carbonyl group / fatty acids and glycerol
Identify and name the following- cocci, bacillus, spirochetes
Cocci = spheres / Bacillus = rods / Spirochetes = spirals
Transcription
DNA → RNA, RNA polymerase binds to a DNA sequence called the promoter which produces a bubble around the DNA, RNA polymerase moves down the template strand and RNA bases are added to the 3' end, RNA peels away, mRNA made
Phenol coefficient
Dilution ratio of disinfectant / dilution ratio of phenol - 1.0 = same effectiveness as phenol - Greater than 1.0 = efficiency greater than phenol - Less than 1.0 = efficiency less than phenol
Role of fimbriae and how its important in STD infections
Fimbriae are projections on gram negative organisms that help a pathogen with adherence, particularly in the urinary and intestinal tracts. Fimbriated cells attach to the mucous membrane epithelium of the cervix and urethra in Neisseria gonorrhoeae.
Endocytosis identify
Endocytosis takes in materials - pinocytosis (small molecules), phagocytosis, and receptor mediated endocytosis (clathrin protein)
Role of endospores
Endospores are formed when a bacterium is exposed to great environmental stress. Occurs in gram positive rods. Resistant to heat, disinfectants, antiseptics, and antibiotics. Bacteria can survive very long in the endospore state. Cause problems for the food industry because of its resistance to heat. Protection against environmental conditions
Plasmids
Extrachromosomal genetic elements that contain virulence factors (genes that allow a pathogen to accomplish its goals), circular pieces
*Identify importance of cilia and flagella
Flagella makes it possible for bacteria to move from their point of origin to other places in the body by spinning 360 degrees. Organisms bind to cilia which can result in whooping cough/pertussis, and diphtheria, cilia help move debris from internal tracts
Difference between layers of peptidoglycan in GP and GN bacteria
GP = thick layer of peptidoglycan / GN = thin layer of peptidoglycan
Types of media to grow anaerobes
GasPak Jar provides an oxygen-free environment for anaerobes to grow in. Sodium thioglycolate forms an oxygen gradient during growth, so anaerobes can grow at the bottom of the tube. Anaerobic blood agar can grow anaerobes.
Generation V Generation time
Generation = each division of bacteria / Generation Time = the time between divisions
Identify which bacteria have outer membranes and how its composed of lipid A and the O polysaccharide (lipopolysaccharides)
Gram negative bacteria have an outer membrane called the lipopolysaccharide (LPS) layer. O polysaccharides are carbohydrate chains found within the lipopolysaccharides. Lipid A anchors the outer membrane to the phospholipid bilayer. If it is released during infection, it becomes an endotoxin which causes a cytokine storm (overactive immune response) Lipid A is bound to the O polysaccharide
Identify a type of disaster, pathogen, and disease that occurs from said disaster
Hurricane Katrina caused an outbreak of tuberculosis (Mycobacterium tuberculosis) and diarrhea from unclean water
Identify cephalosporins and different generations and how it works via porins
Has a greater effect on gram negative than penicillin because of porin channels, 1st generation effects gram positive, older generations effect gram negative and moe resistant pathogens
Example of a microbe that lives at low pH
Helicobacter pylori lives in the low pH of the stomach, causes stomach ulcers
Know the types of heteroglycans
Heteroglycans = polysaccharides that combine 2 different types of monosaccharides (*peptidoglycans)
Types of macrolide antibiotics and what infections are targets
Includes erythromycin, azithromycin, and clarithromycin. Used to treat sexually transmitted infections (gonorrhea and chlyamydia)
Identify stages in a bacterial growth curve
Lag Phase = bacteria adjust to their environment, little cell division --> Log Phase = # of bacteria doubles exponentially, this phases lasts as long as a sufficient level of nutrients remain available (target for antibiotics) --> Stationary Phase = the number of dividing cells equal the number of dying cells, death begins to increase because of lack of nutrients --> Death Phase = continuous decline in the number of dividing cells from exhaustion of nutrients
Identify M proteins as virulence factors and identify strep pyogenes as an example
M proteins protrude through the gram positive cell wall. They are required for infections and are highly susceptible to mutations. Resistant to phagocytosis by host cells in Strep pyogenes. M proteins make Strep pyogenes pathogenic
*Plasmids, what they are, and how they encode virulence
Plasmids are extrachromosomal DNA that encode for virulence factors that give a pathogen its pathogenicity. They carry genes for toxins and antibiotic resistance and can be transferred via the pili during gn conjugation.
The role of porins
Porins are proteins found on the gram negative cell wall. It is a channel that allows for passages of big molecules into and out of the gram negative cell.
What are we seeing with pathogens today
Pathogens are showing increasing resistance to antibiotics. Organisms that were thought to be harmless have been discovered to cause disease in certain circumstances
*8 major categories of chemical agents
Phenols, alcohols, halogens, oxidizing agents, surfactant, heavy metals, aldehydes, gaseous agents
Translation
RNA → proteins, ribosomal subunits binds to mRNA, tRNA binds to the start codon (AUG, methionine) and moves to the P site, tRNA binds to a new amino acid and moves to the A site, a peptide bond is formed between the adjacent amino acids and they both move down the RNA strand, the start tRNA moves to the E site (exit site) and signals release, the amino acid from the A site then moves to the P site and the process continues, process ends when a stop codon is in the A site
What indirect methods are used for counting bacterial cells?
Spectrophotometric method estimates the total number of cells (alive and dead). It is based on the turbidity of a broth culture.
Quinolones and what infections are targets
Target bacterial topoisomerases, block movement of replication fork Used in the treatment of: UTI, osteomyelitis, Community-acquired (walking) pneumonia, gastroenteritis, Anthrax
Folic acid inhibition drugs targets
Target normal enzyme action that incorporates para aminobenzoic acid into the pathway
Identify the definition of teichoic acids
Teichoic acids are in gram positive cells. They hold peptidoglycan in place and provide stability and support for the cell wall.
Loosely attached vs tightly attached glycocalyx
The glycocalyx is a protective element on the outside of the cell. Loose attachment is a slime layer (biofilm). Tight attachment is a capsule (inhibits phagocytosis)
What bacitracin is used for
Used topically for superficial infections by gram positive organisms
Identify and explain how vaccines how contributed to prolonged life within humans
Vaccines prevent new illnesses from spreading and prevent the implications of certain diseases
Antiseptic
associated with human tissue and skin
Selective
contains ingredients that prohibit the growth of some organisms while fostering the growth of others, only grows specific organisms