Exam 1 Flashcards
Germ theory of disease
some diseases are caused by microorganisms that have gained access to the human body
purpose of koch’s postulates
to identify germs with infectious diseases; they became standards for linking a specific organism to a specific disease
Koch’s first postulate
the suspected pathogen must be present in all cases of the disease and absent from healthy animals
Koch’s second postulate
the suspected pathogen must be grown in pure culture
Koch’s third postulate
cells from a pure culture of the suspected pathogen must cause disease in a healthy animal
Koch’s fourth postulate
the suspected pathogen must be reisolated and shown to be the same as the original
two themes of microbiology
- understanding the basic life processes
- applying that knowledge to the benefit of humans
What is microbiology?
microbiology is the study of microscopic life forms, called microorganisms
evolution
the process of change over time that results in new varieties and species of organisms
phylogeny
evolutionary relationships between organisms
Last universal common ancestor (LUCA)
common ancestral cell from which all cels descended
what are viruses composed of and what do they require?
They have a DNA or RNA core surrounded by a protein coat and sometimes a lipid membrane. They require a host to make copies of itself.
what are diversity and the abundances of microbes controlled by?
resources, example nutrients, and environmental conditions like temperature, pH, O2
microbial communities
microorganisms exist in nature in populations of interacting assemblages
nomenclature
gives scientific names to organisms
cytoplasmic (cell) membrane
barrier that separates the inside of the cell from the outside environment
cytoplasm
aqueous mixture of macromolecules, ions, and ribosome
ribosomes
protein-synthesizing structures
genome
an organism’s complete set of DNA, including all of its genes. Each genome contains all of the information needed to build and maintain that organism.
Differences between eukaryotes and prokaryotes
membranes- lipid contents and lipids in prokaryotes do not contain cholesterol unlike eukaryotes, and organelles exist in eukaryotes and. not prokaryotes. Also genomes; prokaryotes have circular chromosomes and eukaryotes do not.
8 True or false? All cells, prokaryote or eukaryote metabolize, grow, and evolve
true
true or false? some cells, prokaryote or eukaryote, are able to differentiate, communicate with other cells, exchange genetic information with other cells, and move
true
enzymes
protein catalysts of then cell that accelerate chemical reactions
DNA replication
DNA chromosome is replicated
transcription
DNA gene is read to produce RNA
Translation
RNA message is read to make protein
What results in growth?
growth is the result of the activities of metabolism; cells use metabolic processes to gain mass, replicate their DNA, and divide
resolution
the smallest distance by which two objects can be separated and still be distinguished
light microscopy
useful for examining cells while they are alive
phase contrast microscopy and differential interference contrast microscopy
exploits the phase of light passing through an object varying thickness and density to produce an image
dark field
illuminating rays are directed from the side, so only scattered light enters the microscope lens
true or false, staining almost always kills the cells
true
What are some uses for a fluorescent microscopy
view a specific cell in a mixture of different cells, and view specific cell components in a cell
morphology
cell shape
coccus (pl. cocci)
spherical or ovoid
rod
cylindrical shape
True or false, morphology typically does NOT predict physiology, ecology, phylogeny, etc.
true
what is the advantage for a cell being small
support greater nutrient exchange per unit cell volume, and tend to grow faster than larger cells
what is the cell wall composed of
peptidoglycan, polysaccharides chains wrapped in circles around cell, and sugar chains
Gram positive
-Capsules
-S-Layer (made of protein)
-Thick cell wall
-Lipoteichoic acids
Gram negative
-Capsule
-Outer Membrane
-Thin cell wall
-Periplasm
-Plasma membrane
Cytoplasmic membrane
surrounds the cell and separates cytoplasm from the environment
hopanoids
pentacyclic chemicals that act to stabilize the bacterial membrane
What is the membrane function
-Permeability barrier
-Protein anchor
-Energy conservation
Integral membrane proteins
firmly embedded in the membrane
Peripheral membrane proteins
one portion anchored in the membrane
Channel (proteins)
Transports solute across membrane. Passive. Often called porins
Carrier (proteins)
Transports solute across membrane. Active or Passive
Receptor (proteins)
Binds extracellular or periplasmic molecules, confirmation change relays information to cell
Enzyme
Facilitates chemical reaction
Nutrient Transport
-Carrier mediated transport systems
-Highly specific
-Three major classes of transport systems in prokaryotes
-All require energy in some form, usually proton motive force or ATP
True or false: carrier transport is faster than simple diffusion
true
Uniporters
transport in one direction across the membrane
Symporters
function as co-transporters
Antiporters
transport a molecule across the membrane while simultaneously transporting another molecule in the opposite direction
Simple transport
driven by the energy in the proton motive force
Group translocation
chemical modification of the transported substance driven by phosphoenolpyruvate
ABC transporter
periplasmic binding proteins are involved and energy comes from ATP
What two types of lipid is the outer membrane of gram negative bacteria made of?
Inner leaflet composed of phospholipid, outer leaflet composed of lipopolysaccharide (LPS)
Fimbriae
Short, helical filamentous protein structure
Capsules and slime layers function
-assist in attachment to surfaces
-protect against phagocytosis
-resist desiccation
Pili
Thin filamentous protein structure
Pili function
allow for bacterial attachment to surfaces, and sometimes allows movement via twitching motility, and often helping bacteria to evade components of the innate immune system.
True or false? Not all bacteria have pili
True
Monotrichuous
single polar flagellum
Amphitricuous
a flagellum at each pole
Lophoticuous
multiple flagella localized at the cell pole
Peritrichous
multiple flagella localized at the cell pole
Taxis
directed movement in response to chemical or physical gradients
chemotaxis
response to chemicals, the best studied movement system
phototaxis
response to light
aerotaxis
response to oxygen
osmotaxis
response to ionic strength
hydrotaxis
response to \water
Conjugation
DNA exchange between two bacteria
Flagella
long, helical protein filaments attached to a complex integral membrane protein “machine”
True or false: not all bacteria have flagella
True
Counterclockwise rotation (CCW)
Push cell forward; with peritrichous lophotrichous the flagella bundle together; some monotrichous cant rotate CCW
Clockwise rotation (CW)
Peritrichous or lophitrichous “tumble”= change of direction; bidirectional monotrichous change direction = backtrack; unidirectional monotrichous= move forward
Taxis
directed movement in response to chemical or physical gradients
chemotaxis
response to chemicals, the best studied movement system
phototaxis
response to light
aerotaxis
response to oxygen
osmotaxis
response to ionic strength
hydrotaxis
response to water
DNA is condensed by
supercoiling
endospore
dormant, non-reproductive structure, that allows bacterial survival in harsh environmental conditions
Metabolism
all the biochemical reactions taking place in an organism
Catabolism
energy-releasing processes
Anabolism
energy-using processes
chemorganotrophs
generate ATP using oxidation of organic compounds
chemolithotrophs
generate ATP using oxidation of inorganic compounds
phototrophs
ATP generated from harnessing light energy
heterotrophs
utilize carbon from organic compounds
autotrophs
utilize carbon from CO2
Free energy (G)
energy released that is available to do work
Exergonic
reactions with a negative delta G zero which release free energy
Endergonic
Reactions with a positive delta G zero require energy
Activation energy
energy required to bring all molecules in a chemical reaction into the reactive state
Catalyst
a chemical that increases the rate of a reaction without undergoing a physical change
Enzymes function to do what
they act as catalysts, lowering activation energy of a specific reaction. They catalyze all chemical reactions in cells.
true or false? Enzymes act through enzyme-substrate complexes
true
cofactors
small non-protein molecules that participate in catalysis but are not substrates
apoenzyme
if an enzyme requires a cofactor to catalyze a reaction and that cofactor is not bound to the enzyme
holoenzyme
an enzyme bound to its cofactor that is active is referred to as a holoenzyme
Feedback inhibition
hinders a metabolic pathway by having a product of the pathway inhibit an earlier reaction
What does an inhibitor do ?
inhibits an enzyme in the pathway so no product is available to feed the next reaction
Noncompetitive inhibition
changing the shape of an active site
Competitive inhibition
blocking an active site
True or false, feedback inhibition can also be competitive or non-competitive inhibitors
true
prosthetic groups
cofactors that are inorganic molecules
coenzymes
organic molecules which include the various NAD+, NADP+, FAD, coenzyme A
Essential nutrients
those that must be supplied from the environment
Macronutrients
major elements in cell macromolecules, and ions necessary for protein function
Micronutrients
trace elements necessary for enzyme function
What does liquid media allow for?
Allows for easily scalable growth, easy to manipulate growth conditions, and allows for continuous culture
What does solid media allow for?
Allows for differentiation by morphology and separation of microbes for further pure culture.
Pure culture
culture containing only a single kind of microbe
Colony morphology
the physical appearance of bacteria grown on a solid media
Selective medium
contains ingredients to inhibit growth of certain species and allow the growth of others
Differential medium
contains specific chemicals to indicate species that possess or lack a biochemical process
Bacterial colony
a visible cluster of bacteria growing on the surface of or within a solid medium, presumably cultured from a single cell
B period
Cell increases in mass and size
C period
The chromosome replicates and the two strands are segregated (separated)
D period
synthesis of a septum forms two identical cells
MreB
major shape-determining factor in prokaryotes
Autolysins
sever pre-existing peptidogylcan creating breaks in the sugar backbone and peptide crosslinks
Transglycolases
enzymes that interact with bactoprenol
Transpeptidases
enzyme that forms the peptide cross links between adjacent glycan chains
Binary fission
cell division following enlargement of a cell to twice its minimum size and the completion of one chromosome replication event!
Fts
essential for cell division in all prokaryotes, and interact to form the divisome
Ftz
forms ring around center of cell
ZipA
anchor that connects FtsZ ring to cytoplasmic membrane
FtsA
helps connect FtsZ ring to membrane and also recruits other divisome proteins
Batch culture
a closed-system microbial culture of iced volume
Lag phase
interval between inoculation of a culture and beginning of growth, No cell division occurs while bacteria adapt to their environment
Logarithmic
when exponential growth of the population occurs. Cells are healthiest in this state. In cases of human disease symptoms usually develop during log phase.
Stationary phase
population growth is limited by one of three factors: 1. exhaustion of available nutrients; 2. accumulation of inhibitory metabolites or end products; 3. exhaustion of space, in this case called a lack of biological space.
Decline/Death phase
the accumulation of waste products and scarcity of resources causes the population to decline in number; Cells die, but this does not mean all of the cells in the culture lose the ability to divide
What does continuous culture allow?
continuous culture allows for a scientist to keep a culture in exponential phase for longer periods than a batch culture
what does optical density of a culture calculate?
the approximate number of bacteria in a sample
Optimal prokaryotic growth is dependent on several physical factor in addition to nutrient levels in the environment
temperature, oxygen concentration, pH, hydrostatic pressure, osmotic pressure
what temperature do psychrophiles grow?
below 15 degrees celsius and make up the largest portion of all prokaryotes on Earth
what temperature do mesophiles live at?
live at the medium temperature range of 10 to 45 degrees celsius including pathogens in the human body
What temperature do thermophiles live best at?
60 degrees celcius in compost heaps and hot springs
Hyperthermophiles are?
archaea that grow optimally above 80 degrees celcius found in seafloor hot-water bents
Homeostasis
the tendency of a biological system to maintain internal stability, owing to the coordinated response of its parts to any situation or stimulus that would tend to disturb its normal condition or function
Obligate aerobes
require oxygen to grow
Microaerophiles
grow in low oxygen environments generally rich in carbon dioxide
anaerobes
Do not or cannot use oxygen during growth
Aerotolerant anaerobes
insensitive to oxygen
Obligate anaerobes
inhibited or killed by oxygen
facultative anaerobes
grow both with oxygen and without oxygen
Capnophilic bacteria (microaerophiles)
require an atmosphere low in oxygen and rich in carbon dioxide
Thioglycollate broth
can be used to test an organism’s oxygen sensitivity
Neutralophiles
grow at pH 5-8, and include most human pathogens
Acidophiles
grow at pH 0-5
Alkaliphiles
grow at pH 9-11
Osmosis
the diffusion of fluid, through a partially permeable membrane, from an area of low solute concentration to an area of high solute concentration
