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179 Cards in this Set
- Front
- Back
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What is morphology? |
size shape and arrangement of cell |
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What are the 3 basic shapes of bacteria? |
cocci (spherical) bacilli (rod-shaped) spirochetes (helical) |
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What are the external/accessory structures of the bacterial cell wall?
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Flagella Pili or Fimbriae Capsule |
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What does the flagella do? |
allows cell to move |
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What does the pili/fimbriae do? |
allows attachment |
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what does the capsule do? |
protects from host defenses, provides osmotic barrier and increases virulence |
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What is the cell wall responsible for? |
shape, nutrient and waste transport, and supports capsule, pili and flagella |
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What does the composition of the cell wall determine? |
whether the organism is gram negative or positive |
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what are structure components of a gram positive cell wall? |
thick peptidoglycan layers and teichoic acid |
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what are structure components of a gram negative cell wall? |
thin peptidoglycan layer, lipids, lipoproteins and lipopolysaccharide |
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What is lipopolysaccharide? |
LPS, The endotoxin |
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What cell wall structure is unique to prokaryotes? |
Peptidoglycan |
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What are the basic nutritional requirements for growth of all bacteria? |
carbon, nitrogen, atp, h2o and other molecules |
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what do autotrophs use as a carbon source? |
CO2 |
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What do heterotrophs use as a carbon source? |
organic substances such as carbohydrates and sugars |
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What is growth media? |
the way you can see bacteria grow |
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what is enriched growth media? |
has added growth factors |
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What is selective growth media? |
has additives that allow/inhibit some bacterial growth |
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What is differential growth media? |
shoes metabolic differences |
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what is transport media? |
Maintains viability of organism while inhibiting reproduction/growth |
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What are the environmental factors for bacteria? |
pH, temperature, and atmosphere |
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What is the optimum pH for most bacteria |
6.0-8.0 |
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What is the optimum temperature classes? |
mesophiles, thermophiles, pschropiles |
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What is the temperature range for mesophiles? |
25-40 C |
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What is the temperature range for thermophiles and where are they found? |
55-80 C in hot springs |
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What is the temperature range for pschrophiles and where are they found? |
below 20 C in arctic seas |
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Which temperature class is the most common? |
mesophiles |
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What are the phases of bacterial growth? |
Lag phase, log phase, stationary phase, and decline |
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What is the lag phase? |
may last a few minutes or many hours as bacteria do not divide immediately. bacteria adapt with vigorous metabolic activity |
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What is the log phase? |
rapid cell division determined by environmental conditions
. |
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What is the stationary phase? |
reached when nutrient depletion or toxic products cause froth to slow until the number of new cells produced balances the number of cells that die. |
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when do bacteria achieve their maximal cell density? |
stationary phase |
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What is decline? |
decline in number of live bacteria |
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What is the bacterial growth curve? |
shows the phases and number of bacterial cells in relation to time. |
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What are obligate aerobes? |
need oxygen to grow |
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What are obligate anaerobes? |
die with oxygen |
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what are capnophiles? |
need increase CO2 |
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What are microaerophiles? |
tolerates oxygen but only in small amounts |
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what are facultative anaerobes? |
use oxygen to generate energy by respiration if present, but can also use the fermentation pathway in the absence of oxygen |
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what are microaerophilics? |
grow best at low oxygen concentration |
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Describe the genomic (chromosomal) DNA. |
single continuous strand of DNA with a closed circular structure |
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What does the bacterial chromosome contain? |
the genetic information that defines characteristics of the organism |
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Describe extrachromasomal DNA (plasmids). |
double stranded circular DNA capable of independent replication within bacterial host. |
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what is the clinical relevance of plasmids? |
they code for antibiotic resistance, resistant to heavy metals, exotoxin production and pili formation |
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What is a gene? |
a chain of purine and pyrimidine nucleotides that are coded with genetic info found in the chromosome. |
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how many copies of each gene do normal bacteria have? what are they called? |
one. haploid organisms |
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how many copies of each gene do higher organisms contain? what are they called? |
two. diploid organisms |
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How do gene variations occur? |
by mutation or gene transfer |
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What is the difference between DNA and RNA nucleotide bases? |
DNA - Adenine -Thymine -and cytosine-guanine RNA- replaces thymine with uracil |
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What does mRNA do? |
contains goad for synthesis of amino acids for protein production |
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What does tRNA do? |
brings specified amino acid to ribosome |
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what is rRNA? |
ribosomal rna |
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What is translation?
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protein synthesis |
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What are the 4 methods of genetic transfer? |
conjugation, transduction, transformation, and transposition |
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What is conjugation? |
bacteria sex. Ability of plasmids to transfer from one bacterial cell to another |
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what is transduction? |
viral transfer of genetic materials |
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what is transformation? |
plasmids and pieces of bacterial chromosomes can be transferred from one bacterial cell to another |
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what is transposition? |
transposons can insert into a sequence of DNA and alter gene expresssion |
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What are transposons? |
jumping genes |
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what is mutation? |
a change in the base sequences of the DNA |
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What are the consequences of mutation? |
inactivates a gene product modify activity creates a new property can be lethal |
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what is metabolism? |
the sum of biological reactions used to provide energy for physiologic processes |
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what is catabolism? |
provides energy by degradation of substrates. (makes little compounds out of big ones) |
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what is anabolism? |
Uses energy by biosythesis. (makes big compounds out of little ones) |
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What is the significance of microbial enzymes? |
defines the biochemical/metabolic pathway of organisms |
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What are sources of energy? |
ATP, carbs, lipids, proteins |
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What are the 3 major pathways for conversion of glucose to pyretic acid? |
Embden-Meyerhof Parnas (EMP) Pentose Phosphate Pathway Entner-Doudoroff |
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What is the Embden-Meyerhof Parnas Pathway (EMP)? |
one 6-carbon glucose converted to two 3-C molecules of pyruvic acid |
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What is the pentose phosphate pathway? |
generates 5C sugars (pentoses) for nucleotide synthesis |
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What is the Entner-Doudoroff pathway? |
converts G-6-P to pyruvic acid to generate NADPH |
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What does pyretic acid undergo? |
respiration or fermentation |
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What does respiration do? |
Provides most energy for the cell
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what happens to the pyruvic acid during respiration?
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it is oxidized into CO2 and H2O |
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How is most ATP generated?
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through aerobic respiration |
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What is fermentation? |
an anaerobic process that is less efficient than aerobic respiration |
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What are the end products of fermentation? |
alcohol, acids and gases |
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What is a pathogen? |
any micro-organism capable of causing disease |
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What is an opportunist? |
micro-organisms that cause disease when host resistance is lowered |
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what is pathogenicity? |
the ability to cause disease
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What is virulence? |
quantitative measure of pathogenicity |
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What is infection? |
invasion of the body with organisms capable of causing disease |
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what is communicable disease? |
infection which is spread from person to person |
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what is contagious disease? |
highly communicable disease |
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what is incidence? |
the number of new events, during a specified period, affecting a specified population |
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what is prevalence? |
the number of cases of a disease present in a specified population at a given time |
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what is endemic? |
infection continuously present in community or group of people (ex. Malaria in Africa) |
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What is epidemic? |
Occurrence of infection in excess of normal expectations (ex. epidemic of flu in winter) |
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What is pandemic? |
infection of extensive distribution (ex. HIV worldwide) |
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What is latent? |
Recurrence of disease/ reactivation of organism |
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what is chronic? |
incomplete elimination of organism |
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What are the stages of disease? |
Incubation period, prodromal period, acute illness, recovery period |
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what is the incubation period? |
the time between invasion of the hows by the infectious agent and appearance of symptoms |
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What is prodromal period? |
early, nonspecific symptoms of a disease
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What is recovery period? |
subsidence of symptoms and return to health |
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What are the different manifestations of infection? |
subclinical (or inapparent) chronic latent |
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what is subclinical manifestation? |
infected with organism but asymptomatic |
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what is chronic manifestation? |
recovery from primary infection but incomplete elimination of pathogen |
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what is latent manifestation? |
reactivation and growth of organism at a later stage with recurrence of disease |
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in what manifestations can disease be spread? |
all of them |
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what are the major steps by which bacteria can cause disease? |
transmission adherence to host surfaces invasiveness toxigenicity |
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what is endogenous transmission? |
caused by normal flora that become opportunistic pathogens
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what is exogenous transmission? |
infections that are acquired from external sources. |
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what is more common? exogenous or endogenous transmission? |
exogenous |
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what are the routes of transmission? |
inhalation ingestion inoculation |
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what is inhalation? |
the airborne route (TB, Influenza) |
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What is ingestion? |
fecal contamination of food. |
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what is inoculation? |
sexual contact, contaminated needles, blood transfusions, biting insects... |
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What are the portals of entry for pathogens? |
skin, respiratory tract, gastrointestinal tract, genitourinary tract |
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what is the first step in the infection? |
adherence |
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what enhances the ability to adhere? |
specialized structures |
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what are the specialized structure that help adherence? |
capsules, pili, fimbrae |
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What are biofilms? |
aggregates of interactive bacteria attached to solid surfaces or to each other in a polysaccharide matrix (Dental plaque) |
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What is invasiveness dependent on?
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secreted bacterial enzymes |
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What plays a critical role in pathogenesis? |
invasiveness |
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What are the two categories of inflammation? |
pyogenic and granulomatous |
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what is pyogenic inflammation? |
pus producing |
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what are the predominant cells in pyogenic inflammation? |
neutrophils |
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What is granulomatous inflammation? |
granuloma forming |
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what are the predominant cells in granulomatous inflammation? |
macrophages and t cells |
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what is a major mediator of bacterial disease? |
toxigenicity |
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what are the two categories to toxins? |
endotoxins and exotoxins |
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where are endotoxins found? |
the LPS of the cell wall that are not actively released - gram negative (bacilli and cocci) |
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what do endotoxins cause? |
fever, shock and hypotension |
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what are the effects of endotoxins due to? |
production of host defense factors in response to bacterial presence |
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what kind of bacteria do not have endotoxins? |
gram positive bacteria |
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what are exotoxins? |
they are secreted by gram- and + bacteria to diffuse into medium |
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how are exotoxins carried? |
by the systemic route |
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what are exotoxins categorized as? |
neurotoxins and enterotoxins |
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where can exotoxins cause symptoms? |
in distant parts of the body |
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what is viral pathogenesis? |
methods by which viruses produce disease in the host |
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What are the factors of viral pathogenesis? |
genetic, immune status, age, nutrition, hormone production, personal habits |
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What are the transmission routes of viral pathogenesis? |
inoculation, inhalation, and ingestion |
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Where are the portals of entry for viruses? |
skin and mucosa oropharynx respiratory tract genitourinary tract |
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When is skin integrity breached? |
abrasions, needle sticks, bites, and punctures |
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What do the natural host defenses of the oropharynx and intestinal tract include? |
desquamation non-specific inhibitory substances (Saliva, acid, bile) and probiotic enzymes mechanical movement of tongue, cheek, peristalsis Immune mechanisms |
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What do the natural hosts defenses of the respiratory tract include? |
mucus secretion ciliary action IgA in secretions Alveolar macrophages |
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What in the genitourinary tract allows final agents to enter? |
abrasions in the GU epithelial tissues |
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What are the natural host defenses of the genitourinary tract? |
mucosal desquamation vaginal and cervical secretions intermitten flushing action of urine |
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What er the mechanisms of viral spread in the body? |
Direct local spread lymphatic spread viremic spread central nervous system and peripheral nerve spread |
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where is direct local spread? |
on epithelial and sub-epithelial surfaces
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where is lymphatic spread? |
filtered through nodes and some escape into blood stream |
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what is viraemic spread? |
entry of virus into blood and its subsequent spread to organs |
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Where does the CNS spread? |
invades blood vessels of meninges and choroid plexus, then goes via CSF to spinal cord and brain |
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What is peripheral nerve spread? |
virus transmitted along nerves (rabies, polio, shingles) |
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What are the 2 main types of viral/host interactions? |
permissive infection non-permissive infection |
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what is permissive infection? |
infection where the is synthesis, assembly and release of viral components in the host cell |
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What is a cytocidal infection? |
the host cell usually dies (during permissive infection) |
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What does permissive infection usually produce? |
an acute illness |
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What is a non-permissive infection? |
a persistent infection where viral replications occur but host cell remains alive |
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What are the 4 categories of non-permissive infection? |
Latent-undetectable chronic-detectible oncogenic slow |
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What is a latent non-permissive infection? |
viral nucleic acids persist in host cell and integrate into host DNA |
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What is chronic non-permissive infection? |
Virus persists in asymptomatic host |
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What is oncogenic non-permissive infection? |
persistent viral infections that trigger cancer |
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what are slow non-permissive infections? |
incubation period can be months to years leading to debilitating disease and death |
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which category of non-permissive infection is rare? |
slow |
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What are electron microscopes? |
they use an electron beam |
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What can be viewed with electron microscopes? |
the internal structures and organisms too small to see with a light microscope |
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what is bacteriology the study of? |
bacteria |
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What is mycology the study of? |
fungi |
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what is parasitology the study of? |
parasites |
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what is virology the study of? |
viruses |
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What atmospheric quality isnt a requirement for most microbes? |
oxygen |
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What are extrachromosomal DNA? |
plasmids |
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How do extrachromosomal DNA replicate? |
independently of chromosomal DNA |
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What do plasmids carry the genes for? |
cell survival |
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what do the cell survival genes do? |
antibiotic resistance exotoxin production heavy metal resistance pili formation |
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What are the general characteristics of culture media? |
solid or liquid forms supports growth sterile |
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What is Nutrient media? |
Complex with meat or soy extracts
supports growth of most bacteria |
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What ar the forms of nutrient media? |
nutrient agar/broth triplicase soy agar/broth |
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What is enriched media? |
has additional growth factors (blood, vitamins, yeast) |
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What are the types of enriched media? |
blood or chocolate agar |
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What is selective media? |
inhibits/helps growth of of bacteria |
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What types of selective media? |
MacConkey, CNA, PEA |
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What is differential media? |
distinguishes based on metabolic differences |
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what are the types of differential media? |
MSA, MacConkeys, Blood |
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What is transport medium? |
a way to preserve viability while inhibiting replication |
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What are prokaryotes? |
bacteria |
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What are eukaryotes? |
parasites |
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what are the differences between prokaryotes and eukaryotes? |
eukaryotes are complex, larger organelles prokaryotes are smaller less complex |
