an infective agent that typically consists of a nucleic acid molecule in a protein coat, is too small to be seen by light microscopy, and is able to multiply only within the living cells of a host : [as adj. ] a virus infection.
a member of a large group of unicellular microorganisms that have cell walls but lack organelles and an organized nucleus, including some that can cause disease.
any of a group of unicellular, multicellular, or syncytial spore-producing organisms feeding on organic matter, including molds, yeast, mushrooms, and toadstools.
an organism that lives in or on another organism (its host) and benefits by deriving nutrients at the host's expense.
strain vs. species
strain: a breed, stock, or variety of an animal or plant developed by breeding.• a natural or cultured variety of a microorganism with a distinct form, biochemistry, or virulence.
species: 1 (abbr.: sp., spp.) Biology a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. The species is the principal natural taxonomic unit, ranking below a genus and denoted by a Latin binomial, e.g., Homo sapiens.
Review growth characteristics of bacteria
on enriched, selective and differential media. Understand terms used to
describe colony morphology, fermentation, and hemolysis of red blood cells.
Enriched- grows many
Selective- some grow
grows BUT they look different
colonies have green halos
complete with clearings
Gama hemolysis- NO
hemolysis, colonies look normal
Microscopic appearnace of indiv. bacterial cells in terms of shapes and arrangement.
spirachete - special spirillum - very axial filament
trepto - chains
diplo - pairs
staphylo - clumps
A common first step in bacterial
identification is the Gram stain. What structure are you staining? How does a
Gram positive cell stain? Gram negative?
Stain cell wall
Gram positive =thick cell wall stain with crystal violet, iodine is mordant crystallizes, alcohol
blows away lipid bilayer (decolorize), counter stain with saphrin
Gram negative = pink, thin layer.
endotoxin is what reacts in body- gives you fever. LPS- lipopysacharide
Describe the role of bacterial glycocalyx.
made up of capsule and slime alyer. both increase virulence.
what are fimbriae and pili?
fimbriae: bristles for sticking
Pili: genetic transfer - bacteria that can make pili have F plasmid "fertility"
are spores produced by Gram + or Gram - bacteria? What is the purpose of a spore? What is inside a spore?
for survival only
bacillus and clostridium cuz they are super hardy so you can't get rid of them
Define obligate aerobe, obligate anaerobe, and facultative anaerobes in terms of oxygen use and enzymes present.
Some organisms are aerobes - can use oxygen
oblicgate aerobes - ust have oxygen in order to make ATP
facultative anaerobes - ferment or use oxygen which is aerobic
Review the three pathways bacteria use to
break down glucose. State which are aerobic, which are anaerobic. Understand
the net energy yield of each.
What is the purpose of an operon? What is
the difference between inducible and repressible operons? Using the lac operon
as an example, state the function of the promoter, sigma factor, operator,
inducible - OFF but can be turned on
Repressible - ON but can be turned off
Lac Operon is inducible - OFF
1. if Lactose is present the repressor is OFF and the operator can transcribe genes.
2. cAMP increases if no glucose is presnt. camp binds CAp and increases prommotor binding = transcription and translation
3. signma factors allow and are needed for RNA polymerase binding
Describe each of these 3 mechanisms of gene transfer: conjugation, transformation and transduction.
a. transformation - bacteria can take up DNA and incorporate it. THey can get a capsule to increase virulence. Can take it from anywhere.
b. Conjugation - swapping genes. Pili- plasmids for antibiotic resistance
c. transposons - jumping genes. have been known to have negative effects and turn off genes.
d. viral transduction - carrying of genes (bacteria can be affected by viruses.
bacterial virus - viral phages
restriction enzymes - cut up foreign DNA
A particular strain of bacteria can be distinguished using antibodies to detect characteristic antigens on the bacteria.
used to identify organisms that are difficult or too dangerous to grow in lab
Describe primary, secondary and tertiary prevention.
Primary: strategies intend to avoid development of disease
Secondary: attempt to diagnose and treate an existing disease in early stage before results in significance morbidity
tertiary: reduce the negative impact of estbalished disease by restoring function and reducing disease-related complications
contrast the size of bacterial cell with eukaryotic cells. State size of an average bacterial cell.
average bacterial cell = 0.2 micron vs. animal cell between 10-100 micro meter
Review cell wall of Gram + and gram - bacteria.
gram + = stain blue, high amount of peptidoglycan in cell wall. lack the outer membrane. cytoplasmic lipid membrane, thick peptidoglycan layer with teichoic acids and lipoids, capsule polsacchardies, flagellum in some
teichoic acids - bacterial polysaccharides. found w/in cell wall of gram + bacteria