Microbio Week 1 (Exam 1) Flashcards
T/F: Very few microbes are always pathogenic
True
Most microbes are _____________ pathogenic; but many are potentially pathogenic if they get in the wrong place
never
Name the method of staining used to differentiate bacterial species into two groups
What are the two groups?
Gram staining
Gram + and Gram -
Gram stain differentiates bacteria by their chemical and physical properties of their cell walls by detecting?
Peptidoglycan
Study of living things too small to see (and viruses)
Microbiology
Dr Graham said “things will stay sterile as long as ______ can’t settle on them”
dust
Difference between bacteria (prokaryotes) and eukaryotes
Bacteria lack organelles
What is a “strain”?
Any isolated colony
What does identification and characterization of bacteria typically first involve?
Growth of laboratory “pure cultures”
_________ examination of specimens is faster, and sometimes available
Direct
T/F A strain of bacteria has a different name than the species it comes from
True!
2 cocci
Diplococci
Cluster of cocci
Staphylococci
Chains of cocci
Streptococci
Curved rod
Vibrio
Spheres
Cocci
Rods
Bacili
What is the primary characteristic for classification of bacteria, and is observed at the same time as the shape and arrangement by light microscopy?
Gram stain
What color is gram + bacteria?
Purple
What color is gram - bacteria?
Pink
Presence of both an inner and outer membrane is characteristic of which bacteria?
Gram -
What oral pathology and lesions can be caused by pathogenic bacteria?
Actinomysis
Diptheria
Scarlet fever
Syphilis
Gonorrhea
Father of Microbiology
Anton van Leeuwenhoek
Name the order of increasing complexity of microbes
Virus
Bacteria
Fungi
Parasite
Two categories of parasites
Protozoa and worms
3 types of fungi
Yeast, mold, dimorphic
Uses an emulsion to trap single nucleic acid templates in wells, PCR amplify them, and then light monitor
Pyrosequencing
Bacteria are best defined as what?
a different type of cell
Who discovered the concept of sterility/germ theory?
Louis Pasteur
What has to be done FIRST in order to identify and characterize bacteria?
Grow a pure culture
Steps of Gram stain
- Prepare heat-fixed film of bacteria on slide
- Stain w/ crystal violet (1 min) and rinse w/ water
- Treat w/ iodine (1 min) and rinse w/ water
- Decolorize with acetone/ethanol (few seconds) and rinse w/ water
- Counterstain with basic fuchsin or safranin (1 min) and rinse w/ water
- Blot dry and view under oil immersion
What would happen if we didn’t decolorize with ethanol?
Everything looks purple
What would happen if we didn’t use safranin?
Gram - would be clear
Overview/steps of bacterial ID
Specimen
Direct exam
Culture
Pure culture and ID to species
Species name established
Typing/fingerprinting for taxonomic or epidemiological purposes
3 characteristics used to ID bacteria
Do they grow w/o oxygen?
Are spores formed?
Are they motile?
Growth requires oxygen as final e- acceptor
Aerobic
Growth uses inorganic molecules or CO2
Anaerobic
Energy generating metabolism which involves the Krebs cycle and oxidative phosphorylation by ETCs
Respiration
Conversion of products of glycolysis to other forms w/o additional ATP gains
Fermentation
Which bacteria are able to form metabolically inert forms that are stable for long periods of time in the environment?
Gram +
(ex: Clostridium and Bacillus)
Example of spore-forming bacteria
Terminal (endo) spore of Clostridium tetani
Example of tetanus agent
Clostridium tetani
What method remains the technology of the future?
Sequencing
What is the best way to compare bacteria? (ON EXAM)
16S rRNA gene sequence alignment (we use genus AND species)
What can you use to obtain lots of DNA for sequencing part of the chromosome that codes for the ribosome’s rRNA?
PCR
T/F: RNA sequencing is the final step in identifying bacteria.
False! It’s DNA sequencing
What is the purpose of PCR?
to amplify a specific desired fragment of DNA
When using a phylogenetic tree, you can get ____ clusters that correspond to _____ domains of life
3; 3
The small ribosome subunit ______ rRNA sequence is widely used, with ____% identify threshold used to define a group as a ______ or ______
16S; 97%; type; species
How many types of bacteria are in the human oral cavity?
700
Do entire genome sequences confirm 16S rRNA phylogeny?
YES
What do microbiologists really only use to classify/name bacteria?
Genus and species
T/F The genus and species must be bolded
FALSE; they must be italicized!
What abbreviation is used to represent multiple species within a genus?
“ssp”
Subtyping test based on differences in microbial surfaces aka antigens
Serotyping
Types of bacteria were first recognized by _______, and ________ _________ like cell shape, surface structures, and ability to grow on different media
staining; visible features
__________ (surface antigens) and identification of secreted and other _________ ___________ then allowed further distinctions of bacteria
Serotyping; enzyme activities
We now have nucleic acid (sequence) analyses, particularly _________ comparisons that indentified relationships between __________
rRNA; species
Bacteria divide by asexual ____________ fission
binary
Bacteria are given nutrients as a source of energy and can grow _____________
exponentially
Bacteria grow and assemble substrates into _______________. Name some examples
macromolecules
examples: polymers, proteins, and nucleic acids
How is the energy for biosynthetic pathways obtained?
respiration or fermentation
How are nutrients obtained?
Uptake
T/F: Bacteria can’t tolerate extreme and variable conditions like nutrients, temp, pH, atmosphere.
False! They CAN tolerate
What does glucose become in glycolysis?
2 pyruvate
How is NAD regenerated after glycolysis?
NADH -> NAD via fermentation (pyruvate becomes lactic acid)
Why is respiration favored over fermentation?
With O2, we can generate much more ATP
Pyruvate is completely oxidized to CO2 via?
Krebs cycle
With oxygen, many bacteria can use the Krebs cycle to then generate much more energy through the?
Electron transport chain (ETC)
In the ETC, ATP is generated by what process?
Oxidative phosphorylation
Carbohydrates or other macromolecules are incompletely oxidized, with pyruvate being converted into organic acids or into ethanol and CO2
Fermentation
What is fermentation useful for?
Identifying bacteria biochemically
Name some other electron acceptors that bacteria can use in anaerobic respiration
Nitrate
Sulfate
Carbonate
Other ions
The use of oxygen or other e- acceptors allows _______ _________ ________ and advantages in different environments
more efficient growth
Anaerobic respiration can produce less/more ATP than aerobic respiration
Less
How many moles of ATP are produced from aerobic respiration?
38
What type of phosphorylation does fermentation use?
substrate-level
Most bacteria we discuss are what type?
Facultative anaerobes
Bacteria that can grow in presence or absence of oxygen
Facultative anaerobes
What is the final electron acceptor in fermentation?
An organic molecule
Which bacteria CANNOT tolerate oxygen?
Obligate anaerobes
Which bacteria can only grow in the presence of oxygen?
Aerobes
Why do bacteria need so much metabolism and energy?
To polymerize biological macromolecules from precursors
Some bacteria have very high nutrient requirements, so they can only live where?
Inside cells
(these are call host dependent intracellular bacteria)
Name 2 common human pathogenic bacteria w/ high nutrient requirements
Genus Mycoplasma
Genus Chlamydiae
Lacks peptidoglycan, small size and genome, cause pneumonia, contributes to pelvic inflammatory disease
Mycoplasma
Two cell forms, requires ATP, causes eye infections, genital infections or pneumonia
Chlamydiae
Which bacteria divide in a coordinated fashion and have a polar septum?
Streptococci
Which bacteria divide in a random fashion and have a random septum?
Staphylococci
There are 4 bacteria at noon and they doubled every 30 mins, how many bacteria would there be at 2pm?
64
Name the phases of the bacterial growth curve
Lag phase
Exponential/log phase
Stationary phase
Decline phase
When is growth initiated?
When diluted bacteria is added to a new liquid culture medium
When is growth terminated?
With depletion of nutrients
T/F All cells in a bacterial population are growing
FALSE
Name of non-growing (phenotypically resting) bacteria on complex biofilm populations that can resist the immune system antibiotics; they can also regrow on removal of treatment
Persisters
What’s an alternative to binary fission? When will it occur?
Sporulation
Occurs when nutrients become limited or the environmental conditions become stressful
Term for not metabolically active
Inert
T/F: All bacteria will form spores.
FALSE; only some bacteria produce spores
Asymmetric cell division to produce a tough survival form called a spore
Sporulation
What are the two most common Gram + bacteria that produce spores?
Bacillus (aerobe)
Clostridium (anaerobe)
What are some characteristics of spore forming bacteria?
-asymmetric division
-metabolically inert
-resistant to solar radiation and drying
-contain all components necessary for regeneration and vegetative growth (like a plant seed or fungal cyst)
What is the only way to kill bacterial spores?
Autoclave or bleach
T/F Bacterial spores can die by a 100 degree boil
FALSE
A structured community of micro organisms that is adhered to a surface and enclosed in carbohydrates and proteins
Biofilm
What diseases are caused by dental biofilm?
Dental caries
Periodontitis
Otitis media
Endocarditis
Name the common biofilm bacteria that causes these diseases
1. caries
2. periodontitis
3. otitis media
4. endocarditis
- strep mutans
- anaerobic Gram (-) bacteria
- Moraxella
- viridans streptococci
Which phase of bacterial growth are endospores MOST likely to form?
Stationary
Which Gram (-) bacteria LACKS peptidoglycan? this is an exception
Mycoplasma
Bacterial cells have a rigid cell ______ surrounding the _________ _________
wall; cytoplasmic membrane
What is the only aspect of bacterial cells more complex than in eukaryotic cells?
Envelope (wall/membrane)
Cell walls maintain ________ and __________ and provide strength to bacteria. This is important in resisting changes in osmolarity of the external environment
size; shape
What does the cytoplasmic membrane of bacteria act as?
Selective permeability barrier
The lipid bilayer also contains ________ machinery, __________ apparatus, and environmental sensors
transport; secretion
____________ ___________ machinery is associated w/ inner or cytoplasmic face for oxidative phosphorylation
Electron transport
Flagella are for ___________ while pili are for _____________
motility; attachment
Physical characteristics specific for Gram + bacteria
Wall
Teichoic acids
Thick peptidoglycan layer
Polysaccharide capsule at outermost surface
