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Microbiology > Lecture Exam 3 > Flashcards

Lecture Exam 3 Flashcards

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Biology 101 flashcards
1
Q

Bacterial growth

A

the process in which from a bacterial cell, two equivalent daughter cells are produced.

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2
Q

What are the four different phases in which bacterial growth can be modeled and what happens during each?

A
  1. Lag phase - bacteria adapt themselves to growth conditions (individual bacteria are maturing)
  2. Log phase or exponential phase - individual bacteria are reproducing at their maximum rate so their numbers increase.
  3. Stationary phase - the growth rate slows due to depletion of nutrients (bacteria begin to exhaust the resources that are available)
  4. Death phase - bacteria run out of nutrients and die.
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3
Q

On a standard growth curve the vertical axis is labeled as what? What does it stand for?

A

On the vertical axis growth is shown as L which = log (numbers) where numbers is the number of colony forming units per mL.

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4
Q

On a standard growth curve the horizontal axis is labeled as what? What does it stand for?

A

T (time)

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5
Q

What are three ways to directly measure bacteria?

A
  1. Spread plate technique (broth) cfu/mL
  2. Filtration
  3. Hemocytometer
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6
Q

What is a way to indirectly measure bacteria?

A

Turbidity

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7
Q

Sterilization

A

removal of all microbial life

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8
Q

Disinfection

A

removal of pathogens

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9
Q

Antisepsis

A

removal of pathogens from living tissue

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10
Q

Sanitation

A

lower microbial counts on eating utensils

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11
Q

What factors do the effectiveness of antimicrobial treatments rely on?

A
  1. number of microbes
  2. type of microbe
  3. environmental factors
  4. time of exposure
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12
Q

How do physical or chemical agents inhibit growth?

A
  1. effect membrane permeability
  2. damage proteins
  3. damage nucleic acids
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13
Q

What are the physical methods to inhibit bacterial growth (microbial control) and how? (be able to list 4-5)

A
  1. heat (autoclave, dry heat, pasteurization): moist heat denatures proteins; dry heat kills by oxidation
  2. low temperature: inhibits microbial growth
  3. filtration: removes microbes
  4. high pressure: denatures proteins
  5. dessication: prevents metabolism
  6. osmotic pressure: causes plasmolysis
  7. UV radiation: damages DNA
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14
Q

What are the chemical methods (types of disinfectants) used to inhibit bacterial growth?

A
  1. Phenols and phenolics
  2. Halogens (Iodine and Chlorine)
  3. Alcohols (ethanol and isopropanol)
  4. Heavy metals (silver, mercury, copper, zinc and selenium)
  5. Quaternary ammonium salts
  6. Aldehydes
  7. Gaseous Sterilizers
  8. Peroxygens
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15
Q

Sepsis refers to:

A

microbial contamination

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16
Q

Asepsis

A

the absence of significant contamination

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17
Q

What do aseptic surgery techniques prevent?

A

microbial contamination of wounds

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18
Q

What type of microbes are very difficult to destroy?

A

Endospores

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19
Q

What type of microbes vary widely in susceptibility to different methods of microbial control?

A

Vegetative pathogens

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20
Q

What type of environmental influences tend to inhibit antimicrobials?

A

the presence of organic material such as blood, feces, and saliva

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21
Q

What is Thermal Death Point (TDP)?

A

Lowest temperature at which all cells in a culture are killed in 10 minutes

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22
Q

What is Thermal Death Time (TDT)?

A

Time to kill all cells in a culture

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23
Q

What is an autoclave used for?

A

Steam sterilization

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24
Q

What does pasteurization do?

A

reduces spoilage organisms and pathogens

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25
Q

(E/C) What are some types of Phenols and Phenolics and what are their advantages?

A
  1. Phenol (carbolic acid) - used in some throat sprays and lozenges; acts as local anesthetic
  2. Phenolics - chemical derivatives of phenol
  3. Cresols - derived from coal tar (Lysol)
  4. Biphenols - effective against gram-positive staphylococci and streptococci; used in nurseries
    ADVANTAGES: Stable, persist for long times after applied, and remain active in the presence of organic compounds.
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26
Q

(E/C) Are halogens effective alone or in compounds?

A

both

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27
Q

(E/C) What are the two types of Halogens?

A

Iodine (iodophores, betadine, isodine)

Chlorine (hypochlorous acid, sodium hypochlorite, chloramines)

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28
Q

(E/C) What is formed when chlorine is mixed with water?

A

hypochlorous acid

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29
Q

(E/C) What is chlorine easily inactivated by?

A

organic material

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30
Q

(E/C) What does alcohol do as a disinfectant?

A
  1. kills bacteria and fungi (not endospores or naked viruses)
  2. denatures proteins and disrupts cell membranes
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31
Q

(E/C) Why is alcohol not good for open wounds?

A

causes proteins to coagulate

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32
Q

(E/C) What are the two types of alcohol?

A

Ethanol - drinking alcohol

Isopopranol - rubbing alchol

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33
Q

(E/C) What are the categories of Heavy Metals used as disinfectants and what are they used for?

A
  1. Silver - protect infants against gonorrheal eye infections
  2. Mercury - disinfect skin wounds
  3. Copper - kill algae in pools and fish tanks
  4. Selenium - kills fungi and their spores; used for fungal infections and in dandruff shampoos
  5. Zinc - zinc chloride used in mouthwashes; zinc oxide used as antifungal agent in paints
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34
Q

(E/C) What are Quaternary Ammonium Compounds used for? What strains are resistant to them?

A

They are widely used surface active agents; they are cationic (positively charged) detergents; effective against gram positive bacteria (less effective against gram negative); destroy fungi, amoebas, and enveloped viruses.
Some Pseudomonas strains are resistant.

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35
Q

(E/C) What are the advantages and disadvantages of Quaternary Ammonium Compounds?

A

Advantages: Strong antimicrobial action, colorless, odorless, tasteless, stable, and nontoxic.
Disadvantages: Form foam. Organic matter interferes with effectiveness. Neutralized by soaps and anionic detergents.

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36
Q

(E/C) What disinfectant group includes some of the most effective antimicrobials? How do they work? What is an example of an aldehyde?

A

Aldehydes - inactivate proteins by forming covalent crosslinks with several functional groups.
Example: Formaldehyde

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37
Q

(E/C) What are gaseous sterilizers? What do they do? Give an example.

A

Chemicals that sterilize in a chamber similar to an autoclave - they denature proteins by replacing functional groups with alkyl groups.
Example: Ethylene Oxide (kills all microbes and endospores but requires exposure of 4 - 18 hours)

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38
Q

(E/C) What do peroxygens do? What do they do? Give an example.

A

Oxidizing agents that oxidize cellular components of treated microbes; disrupt membranes and proteins.
Example: Ozone

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39
Q

What are the top three most resistant types of microbes?

A

Prions (most), endospores of bacteria, mycobacteria

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40
Q

What are the top three least resistant?

A

Viruses with lipid envelopes (least), Gram-positive bacteria, Viruses without envelopes

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41
Q

Genomics

A

Molecular study of genomes

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42
Q

genome

A

All of the genetic material in a cell

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43
Q

gene

A

segment of DNA that encodes a functional product, usually a protien

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44
Q

genotype

A

genes of an organism

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45
Q

phenotype

A

expression of a gene

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46
Q

mutation

A

Change in genetic material - occurs when a DNA gene is damaged or changed in such a way as to alter the genetic message carried by that gene.

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47
Q

genetics

A

study of what genes are, how they carry information, how information is expressed, and how genes are replicated

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48
Q

Define the Central Dogma of molecular Biology.

A

the process by which the instructions in DNA are converted into a functional product. (“the flow of information in a cell”)

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49
Q

Explain the Central Dogma process.

A

The central dogma describes a two step process, transcription and translation by which the information in genes flows into proteins. (DNA - mRNA - Protein)
Transcription is the first step of gene expression, in which a particular segment of DNA is copied into RNA (mRNA) by the enzyme RNA polymerase.
Translation is the process in which cellular ribosomes create proteins. In translation, messenger RNA (mRNA) is decoded by a ribosome to produce a specific amino acid chain, or polypeptide.

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50
Q

How does genetic information flow between generations of cells?

A

The parent cells goes through replication and divides into two daughter cells.

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51
Q

How does genetic information flow between cells of the same generation?

A

through recombination to recombinant cells

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52
Q

Describe the structure and characteristics of DNA. (5 things)

A
  1. Polymer of nucleotides: adenine, thymine, cytosine, guanine (form sequence of 3 neucleotides (codons))
  2. Double helix associated with proteins
  3. “backbone” is deoxyribose-phosphate
  4. strands held together by hydrogen bonds between AT and CG
  5. strands are antiparallel
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53
Q

What does DNA stand for?

A

Deoxyribo Nucleic Acid

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54
Q

Nucleotide (NTS) = ?

A

PO4, deoxyribose, nitrogen base

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55
Q

Describe the structure and characteristics of RNA.

A
  1. single stranded
  2. transient
  3. mRNA serves as a template for ribosome’s to synthesize protein
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56
Q

What enzyme copies DNA (it is considered the main player)?

A

DNA polymerase

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57
Q

In which direction does DNA copy?

A

5 prime to 3 prime

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58
Q

Describe the steps of DNA replication.

A
  1. Enzymes unwind the parental double helix.
  2. Proteins stabilize the unwound parental DNA.
  3. the leading strand is synthesized continuously by DNA Polymerase in a 5 prime to 3 prime direction.
  4. The lagging strand is synthesized discontinuously in a 3 prime to 5 prime direction. RNA polymerase synthesizes a short RNA primer, which is then extended by DNA polymerase.
  5. DNA polymerase digests RNA primer and replaces it with DNA (okazaki fragment)
  6. DNA ligase joins the discontinuous fragments of the lagging strand.
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59
Q

What is a Okazaki fragment?

A

short, newly synthesized DNA fragments that are formed on the lagging template strand during DNA replication. They are complementary to the lagging template strand, together forming short double-stranded DNA sections.

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60
Q

What is the replication fork? What seperates the 2 strands of DNA?

A

the place where the parental double helix strand unwinds and becomes two strands - the leading strand and lagging strand.

  • Helicase
  • Topoisomerase
  • single stranded DNA binding proteins (DNA Polymerase: binds to a sequence of DNA called the origin of replication)
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61
Q

What kind of replication is DNA replication? What does that mean?

A

semiconservative - produces two copies that each contain one of the original strands and one new strand.

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62
Q

What does DNA polymerase bind to in order to initiate synthesis?

A

double stranded nucleic acid

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63
Q

What are some basics of Transcription?

A
  1. DNA is transcribed to make RNA (mRNA, tRNA, and rRNA)
  2. begins when RNA polymerase binds to the promoter sequence. (promoter or TATA box, initiates transcription)
  3. proceeds in the 5 prime to 3 prime direction and does not need a primer
  4. stops when it reaches the terminator sequence
  5. uses nucleotides Adenine, uracil, cytosine, and guanine.
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64
Q

Explain exons and introns in transcription.

A

In most eukaryotic genes, coding regions (exons) are interrupted by noncoding regions (introns). During transcription, the entire gene is copied into a pre-mRNA, which includes exons and introns. During the process of RNA splicing, introns are removed and exons joined to form a contiguous coding sequence. This “mature” mRNA is ready for translation.

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65
Q

Explain the 5 prime cap and 3 prime poly A tail.

A

Eukaryotic pre-mRNA receives a 5’ cap and a 3’ poly (A) tail before introns are removed and the mRNA is considered ready for translation.

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66
Q

How does transcription and translation differ between eukaryotic and prokaryotic cells?

A

Transcription and Translation in Cells. In a prokaryotic cell, transcription and translation are coupled; that is, translation begins while the mRNA is still being synthesized. In a eukaryotic cell, transcription occurs in the nucleus, and translation occurs in the cytoplasm.

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67
Q

What are some basics of Translation?

A
  1. mRNA is translated in codons (3 nucleotides)
  2. Translation of mRNA begins at the start codon: AUG
  3. Translation ends at a STOP codon: UAA, UAG, UGA
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68
Q

What happens during the Initiation stage of translation?

A

(“beginning”): in this stage, the ribosome gets together with the mRNA and the first tRNA so translation can begin.

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69
Q

What happens during the Elongation stage of translation?

A

(“middle”): in this stage, amino acids are brought to the ribosome by tRNAs and linked together to form a chain.

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70
Q

What happens during the Termination stage of translation?

A

(“end”): in the last stage, the finished polypeptide is released to go and do its job in the cell.

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71
Q

Describe the detailed process of translation.

A
  1. components needed to begin translation come together (includes two ribosomal subunits, mRNA with codons, and tRNA with anticodons
  2. the ribosome assembles and on it, at the P site, a tRNA carrying the first amino acid is paired with the start codon on the mRNA.
  3. at the A site next to the P site on the ribosome a second codon of the mRNA pairs with a tRNA carrying the second amino acid
  4. The first amino acid joins to the second by a peptide bond, and the first tRNA is released.
  5. The ribosome moves along the mRNA until the second tRNA is in the P site, and the process continues and new amino acids are added to the polypeptide. (1000 per second)
  6. When the ribosome reaches a stop codon, the polypeptide is released.
  7. Finally, the last tRNA is released, and the ribosome comes apart. The released polypeptide forms a new protein.
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72
Q

Where does translation occur?

A

in the cytoplasm

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73
Q

What are the components of translation?

A

mRNA, tRNA and ribosomal units

74
Q

In translation, how is the genetic code read?

A

starts with the start codon and then reads every 3 from there.

75
Q

What is the basic building block of a protein?

A

amino acids

76
Q

define protein.

A

A molecule composed of polymers of amino acids joined together by peptide bonds.

77
Q

Constitutive enzyme

A

produced in constant amounts without regard to the physiological demand or the concentration of the substrate. They are continuously synthesized because their role in maintaining cell processes or structure is indispensable.

78
Q

Inducible enzyme

A

an enzyme that is expressed only under conditions in which it is clear of adaptive value, as opposed to a constitutive enzyme which is produced all the time. The Inducible enzyme is used for the breaking-down of things in the cell.

79
Q

Structural genes

A

a gene that codes for any RNA or protein product other than a regulatory factor (i.e. regulatory protein). It may code for a structural protein, an enzyme, or an RNA molecule not involved in regulation.

80
Q

Operator site

A

a segment of DNA to which a transcription factor binds to regulate gene expression by repressing it

81
Q

RNA polymerase

A

an enzyme that produces primary transcript RNA.

82
Q

Repressor

A

a substance that acts on an operon to inhibit messenger RNA synthesis.

83
Q

Promoter

A

a region of DNA that initiates transcription of a particular gene

84
Q

Lac operon

A

an operon required for the transport and metabolism of lactose in Escherichia coli and many other enteric bacteria. (catabolic, inducible)

85
Q

Tryp operon

A

an operon that codes for the components for production of tryptophan. The trp operon is present in many bacteria, but was first characterized in Escherichia coli. (anabolic, repressible)

86
Q

Base mutation

A

change in one base

87
Q

Missense mutation

A

result in change in amino acid

88
Q

Nonsense mutation

A

results in a nonsense codon

89
Q

Frameshift mutation

A

insertion or deletion of on or more nucleotide pairs

90
Q

Biotechnology

A

technology based on biology - biotechnology harnesses cellular and biomolecular processes to develop technologies and products that help improve our lives and the health of our planet.

91
Q

plasmid

A

a small, circular, double-stranded DNA molecule that is distinct from a cell’s chromosomal DNA. Plasmids naturally exist in bacterial cells, and they also occur in some eukaryotes. Often, the genes carried in plasmids provide bacteria with genetic advantages, such as antibiotic resistance.

92
Q

selectable marker

A

a gene introduced into a cell, especially a bacterium or to cells in culture, that confers a trait suitable for artificial selection.

93
Q

multiple cloning site

A

also called a polylinker, is a short segment of DNA which contains many (up to ~20) restriction sites - a standard feature of engineered plasmids.

94
Q

restriction enzyme

A

enzymes that cut a DNA molecule at a particular place. They are essential tools for recombinant DNA technology. The enzyme “scans” a DNA molecule, looking for a particular sequence, usually of four to six nucleotides.

95
Q

DNA ligase

A

a specific type of enzyme, a ligase, (EC 6.5.1.1) that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond.

96
Q

DNA transformation

A

the process by which foreign DNA is introduced into a cell.

97
Q

Vector

A

a DNA molecule used as a vehicle to artificially carry foreign genetic material into another cell, where it can be replicated and/or expressed. A vector containing foreign DNA is termed recombinant DNA.

98
Q

Annealing

A

recombine (DNA) in the double-stranded form following separation by heat.

99
Q

recombinant DNA

A

DNA that has been formed artificially by combining constituents from different organisms.

100
Q

What are the steps for recombinant DNA cloning?

A
  1. Isolation of plasma DNa & DNA containing gene of interest.
  2. Gene inserted into plasmid
  3. Plasmid put into bacterial cell
  4. Cells cloned with gene of interest
  5. Identification of desired clone
101
Q

What does the polymerase chain reaction do?

A

makes multiple copies of a piece of DNA enzymatically

102
Q

What is the polymerase chain reaction used for?

A
  1. clone DNA for recombination
  2. amplify DJNA to detectable levels
  3. sequence DNA
  4. Diagnose genetic disease
  5. Detect pathogens
103
Q

What are the 5 components needed for the PCR?

A

a DNA template, DNA polymerase enzyme, primers, nucleotides and reaction buffer.

104
Q

What is a PCR thermocycler

A

a laboratory apparatus most commonly used to amplify segments of DNA via the polymerase chain reaction (PCR).

105
Q

What are the stpes that make up the Polymerase Chain Reaction (PCR)?

A
  1. Melting (denaturation)
  2. Annealing
  3. Extension (elongation)
106
Q

What are the stpes that make up the Polymerase Chain Reaction (PCR)?

A
  1. Melting (denaturation)
  2. Annealing
  3. Extension (elongation)
107
Q

List some Gram positive bacteria.

A 
Streptococcus
Enterococcus
Clostridium
Bacillus
Staphlylococcus
108
Q

List some Gram negative bacteria.

A 
Escherichia coli
Salmonella
Pseudomonas
Moraxella
Helicobacter
Stenotrophomonas
109
Q

Antibiotic

A

Substance produced by a microbe that inhibits another microbe

110
Q

Chemotherapy

A

The use of drugs to treat a disease

111
Q

Antimicrobial drugs

A

Interfere with the growth o microbes within a host

112
Q

Selective toxicity

A

a drug that kills harmful microbes without damaging the host

113
Q

How does a narrow spectrum antibiotic differ from a broad spectrum antibiotic?

A

The term broad-spectrum antibiotic refers to an antibiotic that acts against a wide range of disease-causing bacteria. A broad-spectrum antibiotic acts against both Gram-positive and Gram-negative bacteria, in contrast to a narrow-spectrum antibiotic, which is effective against specific families of bacteria.

114
Q

What are the five types (modes of action) of antibiotics discussed in class?

A
  1. inhibition of cell wall synthesis: Penicillins, cephalosporins, bacitracin, vancomycin
  2. Inhibition of protein synthesis: Chloramphenicol, erythromycin, tetracyclines, streptomycin
  3. Inhibition of synthesis of essential metabolites: Sulfanilamide, trimethoprim
  4. Injury to plasma membrane: Polymyxin B
  5. Inhibition of nucleic acid replication and transcription: Quinolones, rifampin
115
Q

What type of bactericidal antibiotics inhibit bacterial protein synthesis?

A

Aminoglycosides inhibit protein synthesis by binding to a portion of the bacterial ribosome.

116
Q

bacteriocidal

A

causing bacterial cell death

117
Q

What are the 4 main antimicrobial drugs that inhibit protein synthesis and how does each do it?

A
  1. Chloramphenicol - binds to 50S portion and inhibits formation of peptide bond
  2. Erythromycin - binds to 50S portion, prevents translocation (movement of ribosome along mRNA)
  3. Tetracyclines - interfere with attachment of tRNA to mRNA-ribosome complex
  4. Streptomycin - changes shape of 30S portion, causes code on mRNA to be read incorrectly
118
Q

What is the main structure in Penicillins? What other antibiotics are included in this group?

A

beta-lactum ring - cephalosporins, carbapenems, and monobactams

119
Q

How does Bacitracin work?

A

Topical application that works against Gram positives - inhibits cell wall production by blocking the step in the process (recycling of the membrane lipid carrier) which is needed to add on new cell wall subunits.

120
Q

How does Bacitracin work?

A

(inhibitor of cell wall synthesis) Topical application that works against Gram positives - inhibits cell wall production by blocking the step in the process (recycling of the membrane lipid carrier) which is needed to add on new cell wall subunits.

121
Q

What antibiotic is similar to Penicillin? How is it the same? How is it different?

A

Cephalosporins is similar to Penicillins in their mode of action (both inhibitors of cell wall synthesis) but they treat a broader range of bacterial infections. also have structural similarities to penicillin.

122
Q

What is an example of a Macrolides and a Lincosamides and what do they do?

A

Erythromycin and clindamycin - inhibit protein synthesis by binding to a subunit of the bacterial ribosome (50S)

123
Q

What do penicillins do?

A

Inhibit formation of the bacterial cell wall by blocking cross-linking of the cell wall structure. The cell wall is a needed protective casing for the bacterial cell.

124
Q

What do Quinolones do?

A

blocks DNA synthesis by inhibiting one of the enzymes (DNA gyrase) needed in this process.

125
Q

What does Rifampin do?

A

inhibits RNA synthesis by inhibiting on of the enzymes (DNA-dependent RNA polymerase) needed in this process. (RNA is needed to make proteins)

126
Q

What do tetracyclines do?

A

inhibit protein synthesis by binding to the subunit of the bacterial ribosome (30S subunit)

127
Q

What do trimethroprim and Sulfonamides do?

A

blocks cell metabolism by inhibiting enzymes which are needed in the biosynthesis of folic acid which is a necessary cell compound

128
Q

What is Polymyxin B and what does it do?

A

an antibiotic primarily used for resistant Gram negative infections - it binds to the cell membrane and alters its structure making it more permeable. The resulting water uptake leads to cell death.

129
Q

What factors promote antimicrobial resistance?

A
  1. exposure to sub-optimal levels of antimicrobial

2. Exposure to microbes carrying resistance genes

130
Q

Pathology

A

the scientific study of the nature of disease and its causes, processes, development, and consequences

131
Q

Etiology

A

the scientific study of the nature of disease and its causes, processes, development, and consequences.

132
Q

Infection

A

the pathological state resulting from the invasion of the body by pathogenic microorganisms

133
Q

Probiotics

A

microorganisms that have beneficial effects on their host.

134
Q

Koch’s Postulate

A

Criteria proposed by Koch for proving the pathogenicity of an organism.

135
Q

What is the criteria for Koch’s Postulate?

A
  1. the suspected causal organism must be constantly associated with the disease
  2. it must be isolated and grown in pure culture
  3. when inoculated into a healthy plant it must reproduce the original disease.
136
Q

symptom

A

any sensation or change in bodily function that is experienced by a patient and is associated with a particular disease

137
Q

sign

A

Any objective evidence of disease

138
Q

Incidence

A

the rate at which a certain event occurs, as the number of new cases of a specific disease occurring during a certain period in a population at risk

139
Q

Prevalence

A

a measure of the proportion of people in a population affected with a particular disease at a given time.

140
Q

Endemic disease

A

An infectious disease that is present in the community at all times but normally at low frequency

141
Q

Epidemic disease

A

Any infectious disease that develops and spreads rapidly to many people

142
Q

Pandemic disease

A

an epidemic occurring over a very wide area; a global epidemic

143
Q

epidemiology

A

the study of the patterns, causes, and control of disease in groups of people

144
Q

Pathogenicity

A

the capacity of a pathogen to cause disease

145
Q

Virulence

A

the degree of pathogenicity of a given pathogen

146
Q

What does ID50 stand for?

A

infectious dose for 50% of the test population

147
Q

What does LD50 stand for?

A

lethal dose (of a toxin) for 50% of the test population

148
Q

What are the portals of entry for pathogens?

A
  1. mucous membranes
  2. skin
  3. parenteral route (intravenous, subcutaneous, intramuscular)
149
Q

endotoxin

A

a Gram negative substance found in the cell walls of certain bacteria that can be extremely toxic to people, producing fever, shock, and even death.

150
Q

What are some examples of an endotoxin?

A

E.coli, Salmonella typhi, Shigella.

151
Q

What are some examples of an endotoxin?

A

E.coli, Salmonella typhi, Shigella.

152
Q

Exotoxin

A

a toxic substance, made by bacteria and released outside the bacterial cell

153
Q

What are some examples of exotoxins?

A 
Corynebacterium diphtheriae
Streptococcus pyogenes
Clostridium botulinum
Clostridium tetani
Vibrio cholerae
Staphylococcus aureus
154
Q

What are the three main types of exotoxins?

A
  1. Superantigens that act upon the extracellular matrix or connective tissue allowing the further spread of bacteria and therefore a deeper infection into the tissue regions (type 1 toxins)
  2. Exotoxins that damage host cell membranes (type 2 toxins; Gangrene caused by Clostridium perfringens)
  3. A-B toxins and other toxin that ingerfere with host cell function (type 3 toxins; cholera toxin, pertussis toxin)
155
Q

What specifically do Superantigens or type 1 toxins do?

A
  • Cause an intense immune response due to release of cytokines from host cells
  • Can result in fever, nausea, vomiting, diarrhea, shock, death (CAUSES SHOCK)
156
Q

What is a cytokine?

A

a soluble proteinaceous substance produced by a wide variety of haemopoietic and non-haemopoietic cell types, and are critical to the functioning of both innate and adaptive immune responses.

157
Q

What specifically do Membrane-disrupting toxins or type 2 toxins do?

A

Lyse host’s cells by:

  • Making protein channels in the plasma membrane
  • Disrupting the phospholipid bilayer
  • Lyse’s WBC; anaerobic
158
Q

What specifically do A-B toxins or type 3 toxins do? (steps)

A
  1. Bacterium produces and release exotoxin.
  2. B (binding) component of exotoxin binds to host cell receptor in the plasma membrane and exotoxin enters the cell.
  3. A (active) component of exotoxin alters cell function by inhibiting protein synthesis.
159
Q

What is the source of exotoxins?

A

mostly Gram positive

160
Q

What is the metabolic product of exotoxins?

A

By-product of growing cell

161
Q

What is the chemistry of exotoxins?

A

Protein

162
Q

Do exotoxins produce fever?

A

no

163
Q

Can exotoxins be neutralized? by what?

A

Yes - by antitoxin

164
Q

What is the LD50 for exotoxins?

A

small

165
Q

What type of exotoxin does Corynebacterium diphtheria produce?

A

A-B toxin - inhibits protein synthesis

aerobic, nonsporulated, EF2 binds, causes death

166
Q

What type of exotoxin does Streptococcus pyogenes produce?

A

Membrane disrupting - Erythrogenic

167
Q

What type of exotoxin does Clostridium botulinum produce?

A

A-B toxin - neurotoxin

168
Q

What type of exotoxin does Clostridium tetani produce?

A

A-B toxin - neurotoxin

169
Q

What type of exotoxin does Vibrio cholerae produce?

A

A-B toxin - enterotoxin

170
Q

What type of exotoxin does Staphylococcus aureus produce?

A

Superantigen - enterotoxin

171
Q

What is the LD50 for endotoxins?

A

Relatively large

172
Q

What is the metabolic product of endotoxins?

A

Present in LPS of outer membrane

173
Q

What is the chemistry of endotoxins?

A

lipid

174
Q

Do endotoxins produce fever?

A

yes

175
Q

Can endotoxins be neutralized by antitoxin?

A

no

176
Q

How do endotoxins work? (steps)

A
  1. a mocrophage ingests a gram-negative bacterium
  2. The bacterium is degraded in a vacuole, releasing endotoxins that induce the macrophage to produce interleukin-1 (IL-1)
  3. IL-1 is released by the macrophage into the bloodstream, through which it travels to the hypothalamus of the brain
  4. IL-1 induces the hypothalamus to produce prostaglandins, which reset the body’s “thermostat” to a higher temperature, producing fever.
177
Q

What are the pathogenic properties of Fungi? (11)

A
  1. Fungal waste products may cause symptoms
  2. Chronic infections provoke and allergic response
  3. Tichothecene toxins inhibit protein synthesis - Fusarium
  4. Proteases - Candida
  5. Capsule prevents phagocytosis - Cryptococcus
  6. Ergot toxin - Claviceps
  7. Aflatoxin - Aspergillus
  8. Mycotoxins - Nerutoxins: Phalloidin, amanitin
  9. presence of protozoa
  10. Protozoan waste products may cause symptoms
  11. Avoid host defenses by growing in phagocytes and antigenic variations
178
Q

What fungi is responsible for producing mycotoxins in cereal crops that can affect human and animal health? (cause of entire livestock having to be put down)

A

Fusarium (Ascomycota)

179
Q

What are Portals of exit for pathogens in our body?

A
  • respiratory tract (coughing sneezing)
  • Gastrointestinal tract (feces, saliva)
  • Genitourinary tract (urine, vaginal secretions)
  • Skin
  • Bood (biting arthropods, needles/syringes)
180
Q

Describe the Mechanisms of Pathogenicity

A
  1. Portals of Entry
    (affecting factors: Number of invading microbes, Adherence)
  2. Penetration or Evasion of Host Defenses (i.e. capsules, cell wall components, enzymes, siderophores, etc)
  3. Damage to Host Cells/Cytopathic Effects (i.e. direct damage, toxins, lysogenic conversion)
  4. Portals of Exit

Microbiology (21 decks)

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