IntroMicro Flashcards
Microbiology
Mycology
Protazoology
Parasitology
Bacteriology
Virology
Archea
Microbes are Everywhere
Microbiology-the study of ________, ___________________________.
Microbes are ____________
Microbes may be ____ or ____
Microbes exist _____, or _____
¡Microbiology-the study of microorganisms, single-celled microscopic organisms.
¡
¡Microbes are independent life-forms
¡
¡ Microbes may be prokaryotic, or eukaryotic
¡
¡Microbes exist free living in the environment, or colonize a host.
It’s a Microbial World
Microbes live in large numbers in ___ and ____
____ ____, and are important for ____ ____
Saprophytic bacteria
¡Microbes live in large numbers in soil and water
¡
¡Metabolically diverse, and are important for nutrient cycling
Break down dead material
The original life on Earth
¡Microbes are the __________________
¡Bacteria ________________.
¡Microbes are the oldest forms of life on Earth
¡Bacteria created an oxygenated atmosphere
The Microbes Within
¡Bacteria can act as____
_____
____
____
____
_____: ____
¡Bacteria can act as symbionts:
§Other microbes
§Plants
§Invertebrates
§Insects
§Animals
▪Ruminants
It’s the Microbiome! = _____= ______
¡Important for ____
¡Can cause____
_____
§Ex)
¡The Human Flora
¡The bacteria that live on us and in us
¡Important for health
¡Can cause disease
¡“Balance”
§Taking antibiotics for an infection
§Destroying the gut microbiome
Bacteriology
Procaryotes vs Eucaryotes
Size:
much smaller than eukaryotes, which are
No
Size: 0.1-3 microm
much smaller than eukaryotes, which are > 5 microm
No membrane-bound organelles
no nucleus, mito-chondria, endoplasmic reticulum, Golgi, etc., which are characteristic of eukaryotes
Bacterial genomes
- ____(most eukaryotes are ____)
- typically ___ chromosome of ____-stranded, ________, _____ DNA
- not contained by a ____ ____ as in eukaryotes
- DNA is___________ in an area called the ____
- organized in ____ coiled loops due to associated ___ and ____
- haploid (most eukaryotes are diploid)
- typically one chromosome of double-stranded, super-coiled, circular DNA
- not contained by a nuclear membrane as in eukaryotes
- DNA is free in cytoplasm in an area called the nucleoid
- organized in 40-50 coiled loops due to associated RNA and proteins
Bacteria may contain plasmids
____ ____ ___-_____ DNA
•may confer ____ ____
_____/____ genes
•–i.e. ___ ____
- small circular extra-chromosomal DNA
- may confer antibiotic resistance
- toxicity/virulence genes
- –i.e. anthrax toxins
Bacterial genes
•do not contain ____
_____: _________________and ______________
•_________: ________________
Bacterial genes
•do not contain introns
•
•operons: functionally related genes tandemly arrayed and co-transcribed to yield a polycistronic mRNA
•
•transcription-translation coupling: translation begins as mRNA being transcribed
•
•
Bacterial Cell Membrane
Cytoplasmic membrane
▪Lipid bilayer with_______________
▪Forms a ___ ___ between the____ and ____
▪____/____
▪____ of ____
- _____
- _______
- _______
▪Gram + bacteria have ___ membrane, Gram – bacteria have ___
§Cytoplasmic membrane
▪Lipid bilayer with embedded membrane proteins
▪Forms a selective barrier between the cytoplasm and environment
▪Diffusion/Transport
▪Generation of gradients
Proton motive force
Concentration of nutrients
Exclusion of wastes/toxins
▪Gram + bacteria have one membrane, Gram – bacteria have two
Cell Wall
Cell Wall
- Located just outside the __________
- Gives bacterium ___ and ___
- Composed of ____
- •Only found in ____
- Protects against ____ ____
- Different_____ in Gram – and Gram + bacteria
Cell Wall
- Located just outside the cytoplasmic membrane
- Gives bacterium rigidity and shape
- Composed of peptidoglycan
- Only found in prokaryotes
- Protects against osmotic lysis
- Different thickness in Gram – and Gram + bacteria
Cell Wall Peptidoglycan
•____ ____ chains ___-____ by ___ ____ ____
- Polysaccharide chain:
- repeating ____ of _______ and________
- cleaved by ___ ____yielding a ____ which____ unless _____ ___
- Cross-linking peptides
- _________
- always linked to ___ ___via ____
- ____ ___-____ _______ catalyze _____________
- •called _______________ because they are targets for___ and other ______
•
•Linear polysaccharide chains cross-linked by short peptide chains
•
•Polysaccharide chain:
•repeating disaccharide of N-acetylmuramic acid (M) and N-acetylglucosamine (G)
•cleaved by host lysozyme yielding a spheroplast which lyses unless osmotically stabilized
•
•Cross-linking peptides
•vary with species
•always linked to carbohydrate chains via muramic acid (M).
•Cytoplasmic membrane-bound transpeptidases catalyze the cross-linking reactions
•called penicillin-binding proteins (PBPs) because they are targets for penicillin and other b-lactam antibiotics.
•
Gram Positive Bacteria
- ____ _____ wall (__-__Å)
- consists mainly of ________
- also contains _____ and _____
- •polymers of ____ (or ____) and ____
- •teichoic acid is _____________
- •lipoteichoic acid is _________________ by _________________
•thick multilayer wall (150-500 Å)
•consists mainly of peptidoglycan
•also contains teichoic and lipoteichoic acids
•polymers of glycerol (or ribitol) and phosphate
•teichoic acid is cross-linked to peptidoglycan
•lipoteichoic acid is anchored to the cytoplasmic membrane by covalently attached fatty acid
¡
Gram Negative Bacteria
¡Peptidoglycan layer
____;
lies________
¡Outer membrane
•lies ____________
•contains ___ ____ ____ ____, which allow ________________
•_________ constitutes the ___ ___
•
¡Periplasmic space
•bounded by _____ and ____
•contains a variety of ____ ____s including ____ _____ (e.g., ______)
•
¡
¡Peptidoglycan layer
•thin; lies outside the cytoplasmic membrane
•
¡Outer membrane
•lies outside the peptidoglycan layer
•contains pore-forming porin proteins, which allow entry of small hydrophilic molecules
•lipopolysaccharide (LPS) constitutes its outer leaflet
•
¡Periplasmic space
•bounded by cytoplasmic and outer membranes
•contains a variety of hydrolytic enzymes including virulence factors (e.g., collagenase)
•
¡
Lipopolysaccharide (LPS)
- occurs in the ___ ____ of the___ ____of Gram ___ bacteria.
- also known as ____
- a powerful ____ of the ____ ____
- endotoxin activity due to ___ ___
- O-antigens
- •___ ____
- •useful for _______ _____
- occurs in the outer leaflet of the outer membrane of Gram(-) bacteria.
- also known as endotoxin.
- a powerful stimulator of the immune response
- endotoxin activity due to lipid A
- O-antigens
- strain-specific
- useful for serologic identification
Cell Wall: Peptidoglycan & the Gram Stain
•Gram(+) bacteria have a ____peptidoglycan cell wall, which ___________ (a __________complex)
•
•Gram(–) bacteria have a ____ peptidoglycan layer, which allows the stain to be ____ ____away
•
•
•Gram(+) bacteria have a thick peptidoglycan cell wall, which traps the Gram stain (a crystal violet-iodine complex)
•
•Gram(–) bacteria have a thin peptidoglycan layer, which allows the stain to be readily washed away
•
•
External Appendages
___
____
_____
____
¡
§ Flagella
§ Pili
§Fimbriae
§Capsule
§
¡
¡
Cell Wall Morphology
___
____
____
____
____ and ___
____
Bacterial Reproduction and Growth
____ reprod via ____ ____
____ offspring
Cell division
- asexual reproduction via binary fission
- Clonal offspring
Genetic Transfer
¡Transfer of DNA between bacteria occurs ____________
Types:
¡Bacteria can share _____________by genetic transfer (___ ___)
¡Transfer of DNA between bacteria occurs separately from cell division
§Transformation
§Transduction
§Conjugation
¡Bacteria can share favorable new genes by genetic transfer (antibiotic resistance)
Growth Phases
- Lag phase:
- period of ____ to ____ ____
•Log or exponential phase:
____ ___
___ ____ is characteristic of the ___
- Stationary phase:
- ___ or____become ____ or ____ metabollic products _____
- cell division rate __ cell death rate
- Death phase:
- cell death rate_ cell division rate
¡
•Lag phase:
•period of adaptation to new condition
•
•Log or exponential phase:
•optimal growth
•doubling time is characteristic of the strain
•
•Stationary phase:
•nutrients or oxygen become limiting or toxic metabolic products accumulate
•cell division rate = cell death rate
•
•Death phase:
•cell death rate > cell division rate
•
¡
Growth Rate is Dependent on Environmental Conditions
¡Bacteria occupy diverse habitats, and have ____ ____ of ___ and ____ for ____
Resources: __ ___ ____ _____ _____ ____. macro, micro, donor, acceptor, C N
Conditions: ___ ___ ___ ___ ___ ____ light T pH osmolarity O2water
¡Bacteria occupy diverse habitats, and have favored sources of energy and conditions for growth
Resources: C, N, macronutrients, micronutrients, O2 (e acceptor), inorganic e donor
Conditions: T, pH, water, O2, Light, Osmotic conditions
