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