Micro Final SG Flashcards
What are Koch’s Postulates and why are they important.
Koch’s postulates are a sequence of experimental steps for directly relating a specific microbe to a specific disease. Are used to prove the cause of an infectious disease.
- The same pathogen must be present in every case of the disease
- The pathogen must be isolated from the diseased host and grown in pure culture.
- The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal.
- The pathogen must be isolated from the inoculated animal and must be shown to be the original organism.
What was some of the important work of Louis Pasteur?
Louis Pasteur (1861)- Reasoned that microbes in the air were the agents responsible for contaminating nonliving matter and are also present in non-living solids, & liquids.
1. Pasteur first poured beef broth into a long necked flask. Next he heated the neck of the flask and bent it into an S-shape; then he boiled the broth for several minutes. Microorganisms did not appear in the cooled solution, even after long periods. (The bend prevented microbes from entering the flask.)
2. Pasteur also solved the spoilage problem by heating the beer and wine just enough to kill most of bacteria–Pasteurization.
3. He also discovered the process of fermentation.
4. Pasteur is also discovered- Germ Theory of disease (1857) (Father of Microbiology)
Compare a eukaryotic cell to a prokaryotic cell
Eukaryotic Cells:
-DNA bound to protein
-DNA is linear
-Usually introns
-In organelles: Has a nucleus, membrane bound
-80 ribosomes
-In reproduction: Mitosis & Meiosis
-Chromosome paired (diploid)
Larger (10-100)
Organism type: multicellular
EX: Animals, Plants, fungi, protists cells
Prokaryotic cells:
-DNA is naked
-DNA is circular
-Usually no introns
-In organelles: No nucleus, no membrane-bound
-70s ribosomes
-In reproduction: Binary fission
-Single chromosomes (haploid)
-Average size: Smaller (1-5)
-Organism type: Unicellular
-EX: Bacteria & Archaea
Microbial Growth: Microbial growth curve: explain each part
During the lag phase, there is little or no change in the number of cells, but metabolic activity is high.
During the log phase, the bacteria multiply at the fastest rate possible under the conditions provided
During stationary phase, there is an equilibrium between cell division and death.
During the death phase, the number of deaths exceeds the number of new cells formed.
What are the products of fermentation of bacteria? Yeast?
Fermentation- releases energy from sugars or other organic molecules by oxidation; anaerobic process
-When bacteria ferments grape juice, it produces lactic acid
-When yeasts ferment grape juice, it produces alcohol
What is mutation?
- is a change in a nitrogenous base sequence of DNA; that change causes a change in the product coded for by the mutated gene. (Changes a bacterium’s genotype)
Types of mutations
-A base substitution occurs when one base pair in DNA is replaced with a different base pair.
-Alterations in DNA can result in missense mutations, frameshift, or nonsense mutations.
-Spontaneous mutations occur without the presence of any mutagen
What is Transduction?
-In this process, DNA is passed from one bacterium to another in a bacteriophage and is then incorporated into the recipient’s DNA.
-In generalized transduction, any bacterial genes can be transferred.
-Needs a virus; can happen randomly or specialized (carries)
What is transformation?
During this process, genes are transferred from one bacterium to another as “naked” DNA in solution.
What is Conjugation of bacteria?
-This process requires contact between living cells.
-One type of genetic donor cell is an F+; recipient cells are F-. F cells contain plasmids called F factors; these are transferred to the F- cells during conjugation.
-Uses a pillis; the plasma DNA can be donated to a recipient.
What is an operon?
-An operon is a unit of DNA that’s going to control an anabolic pathway.
-Gene expression is regulated by Operons.
Explain an inducible operon
Mostly off so that it can be induced. Presence of a lot of substrate will induce operon. Ex: Lactose Operon.
Explain arepressible operon
Enough product will interact with repressor protein & bind to repressor and make it fit on the operon.
-Transcribed continuously until deactivated by repressors. EX: Tryptophan Operon
What produces the repressor protein?
The Regulatory gene
What is first, second and third in the operon process?
-The first is regulatory gene that produces the repressor protein.
-The second is the promoter region which is where the enzyme RNA polymerase will latch on and begin transcription of DNA to produce an mRNA transcript strand.
-The third is the operator which serves as an on and off switch. When operon is on, the mRNA is working to transcribe. When off, the mRNA transcription stops.
Which one is always on? Which one is off until needed?
-Inducible Operon is mostly off.
-Lac Operon is always on
Chemotherapy
the use of drugs/chemicals to treat a disease
Antimicrobial drugs
Synthetic substances that interfere with the growth of microbes within a host
Antibiotics
a substance produced by a microbe that, in small amounts, inhibits another microbe
Selective Toxicity
selective finding and destroying/killing harmful microbes (pathogens) without damaging the host
Bactericidal
Kills microbes directly
Bacteriostatic
Prevents microbes from growing
Superinfection
overgrowth of normal microbiota that is resistant to antibiotics
Explain ways drugs target microbes:
1.Inhibition of cell wall synthesis- cephalosporins, bacitracin, vancomycin
- Inhibition of protein synthesis- erythromycin, tetracyclines, streptomycin, chloramphenicol
- Inhibition of nucleic acid replication & transcription: Quinolones, rifampin
- Inhibition of essential metabolite synthesis: Sulfonamide, Trimethoprim
What does Chloramphenicol do?
Binds to 50S portion and inhibits formation of peptide bond
What does Erythromycin do?
binds to the 23S rRNA molecule in the 50S subunit not allowing tRNA to attach
What does Tetracyclines do?
interfere with the attachment of tRNA to mRNA- ribose complex
What does Streptomycin do?
Changes shape of 30S portion, causing code on mRNA to be read incorrectly
Explain ways microbes can resist drugs:
A variety of mutations can lead to antibiotic resistance
- Blocking entry, prevention of penetration to the target site within microbe
- Inactivation or destruction by enzymes
- Alteration of target molecule/site
- Rapid efflux (rapid ejection) of the antibiotic
Variations of mechanisms of resistance
What are Persister cells?
microbes with genetic characteristics allowing for their survival when exposed to an antibiotic
Superbugs are ____
bacteria that are resistant to large numbers of antibiotics
Resistance genes are often spread _________ among bacteria of __________ or transposons via conjugation or transduction
horizontally, of plasmids
How do microbes develop resistance?
-Through mutation and selection
-Initiation of antibiotic therapy
-Antibiotic resistance of bacterial population measured by amount of antibiotic needed to control growth
What is an exotoxin?
are proteins produced inside pathogenic bacteria, most commonly gram-positive bacteria, as part of their growth and metabolism. Exotoxins are then secreted into the surrounding medium during log phase. Toxic substances released outside the cell. EX: Clostridium Botulinum gram (+) produces exotoxins.
What is an Endotoxin?
are the lipid portions of lipopolysaccharides (LPS) that are part of the outer membrane of the cell wall (-) bacteria. The endotoxins are liberated when the bacteria die and the cell wall breaks apart. EX: Salmonella Typhimurium, is gram (-) bacterium that produces endotoxins.
Virulence factor structural components?
-Lipotechoic acid: in cell wall increases adherence to epithelial cells
-Protein M and fimbriae: interferes with opsonization and complement binding
-Capsule made of hyaluronic acid: camouflage the bacteria from WBCs
-Many other adhesion proteins
Virulence factors Enzyme Examples:
-Streptokinase- digest bloot clots
-Hyaluronidase- breaks down connective tissue
-Deoxynucleases- depolymerizes DNA
-C5a Peptidase- cleaves and inactivates C5a (chemotaxin for WBCs)
Virulence Factors Toxins examples:
-Streptolysins (hemolysins)- rupture RBCs, WBCs, platelets, liver cells and heart muscle cells
-Pyrogenic toxins (erythrogenic toxin)- stimulate macrophages and Th to release cytokines
Virulence can be expressed as LD50 (___________for 50% of the inoculated hosts) or ID50 (__________ for 50% of the inoculated hosts.) ID50 would be more dangerous.
-lethal dose
-infectious dose
What are the different stages in a disease?
- Incubation Period- is the interval between the initial infection and the first appearance of any signs or symptoms. (depends on the specific pathogen)
- Prodromal Period- short period that follows the period of incubation in some diseases. It is characterized by early, mild symptoms of disease, such as general aches and malaise.
- Period of Illness- The disease is most severe. The person exhibits overt signs and symptoms of disease. WBC↑or↓
4.Period of Decline- signs and symptoms subside. Pt may be vulnerable to secondary infections in this stage.
5.Period of Convalescence- regains strength and the body returns to its predeceased state. Recovery has occurred.
True or False
During the period of illness, people can spread disease easily. Can people also spread disease during the incubation and prodrome periods?
True
What are the components of the three different lines of defense in host defenses?
First line of Defense: Keeps pathogens on the outside or neutralize them before infection begins. The skin, mucous membranes, normal microbiota, and certain antimicrobial substances are part of these defenses.
Second line of Defense: slow or contain infections when first-line defenses fail. They include proteins that produce inflammation. Fever that enhances cytokine activity, and phagocytes and natural killer (NK) cells, which attack and destroy cancer cells and virus-infected cells.
Third Line Defenses: Include lymphocytes (T & B cells) and antibodies that target specific pathogens for destruction when the second-line defenses don’t contain infections. It includes a memory component that allows the body to more effectively respond to that same pathogen in the future.
`______ immunity involves the first and second line of defenses.
Innate
______ immunity involves the third line of defenses
Adaptive
Innate immune actions are ______ but _________.
-fast
-nonspecific
Adaptive immune cells are __________, but _________ to pathogens, and have a memory component.
-slower
-specific
What is complement? What are some functions?
-The complement system consists of a group of serum proteins that activate one another to destroy invading microorganisms.
-Complement proteins are activated in a cascade.
-C3 activation can result in cell lysis, inflammation, and opsonization
-Complement is activated via the classical pathway, the alternative pathway, and the lectin pathway.
-Complement deficiencies can result in an increased susceptibility to disease.
- Some bacteria evade destruction by complement by means of capsules, surface lipid-carbohydrate complexes, & enzymatic destruction of C5a.
Complement are serum proteins activated by antigens, proteins, and pathogens in a cascade. It is another way the body fights infection and destroys pathogens. It is a component of ____________ immunity.
Innate
Proteins destroy microbes by __________, enhanced ___________ (opsonization), and inflammation.
-cytolysis
-phagocytosis
______ activation can result in cell lysis, inflammation, and opsonization.
C3
What are the 5 white blood cells and their functions in the immune response?
Granulocytes
Neutrophils (60-70% of leukocytes) Function: Phagocytosis of bacteria & fungi
Basophils (0.5-1%) Function: Production of histamine that cause inflammation
Eosinophils (2-4%) Function: Production of toxic proteins against certain parasites; some phagocytosis. Kills parasites w/ oxidative burst.
Agranulocytes
Monocytes (3-8% total) Function: Phagocytosis (precursor to macrophages)
Lymphocytes (20-25%) 1. Natural Killer cells Function: Destroy target cells by cytolysis and apoptosis
2. T cells Functions: cell-mediated immunity
3. B cells Function: produce antibodies
What are the 5 white blood cells?
Neutrophils
Basophils
Eosinophils
Monocytes
Lymphocytes
Their functions in the immune response?
Granulocytes
Neutrophils (60-70% of leukocytes) Function: Phagocytosis of bacteria & fungi
Basophils (0.5-1%) Function: Production of histamine that cause inflammation
Eosinophils (2-4%) Function: Production of toxic proteins against certain parasites; some phagocytosis. Kills parasites w/ oxidative burst.
Agranulocytes
Monocytes (3-8% total) Function: Phagocytosis (precursor to macrophages)
Lymphocytes (20-25%) 1. Natural Killer cells Function: Destroy target cells by cytolysis and apoptosis
2. T cells Functions: cell-mediated immunity
3. B cells Function: produce antibodies
Which white blood cells are granulocytes?
Neutrophils
Basophils
Eosinophils
Which white blood cells are agranulocytes?
Monocytes
Lymphocytes
What is a mast cell?
Antigen presenting cells (APC); produce antibacterial peptides.
What is the progression of events to a fever?
-Abnormally high blood temperature
-Hypothalamus is normally set at 37 degrees
-Gram-negative endotoxins cause phagocytes to release interleukin-1 (IL-1)
-Hypothalamus releases prostaglandins that reset the hypothalamus to a high temperature
-Body increases rate of metabolism, and shivering occurs, which raise temperature.
-Vasodilation and sweating: body temperature falls (crisis)
What is inflammation?
-Inflammation is a bodily response to cell damage; it is characterized by redness, pain, heat, swelling, & sometimes the loss of function.
What stimulates production of acute-phase proteins leukotrienes and cytokines in inflammation?
TNF-alpha
____________ increases permeability of blood cells/vessels due to damaged tissue in inflammation.
Vasodilation
Inflammation can be classified as ______ or __________.
Acute or chronic
What happens in an inflammatory response?
1.Chemicals such as histamine, kinins, prostaglandins, leukotrienes, & cytokines are released by damaged cells
2.Blood clot forms.
3.Abscess starts to form.
4.Margination- phagocytes stick to endothelium.
5.Diapedesis- phagocytes squeeze between endothelium cells.
6.Phagocytosis of invading bacteria occurs.
