Prokaryote Structure & Gram Stain Flashcards
Prokaryotes differ from eukaryotes in that they do not contain any organelles with _
Prokaryotes differ from eukaryotes in that they do not contain any organelles with membranes
* They lack a nucleus, ER, mitochondria, golgi, lysosomes, peroxisomes
* Bacteria also don’t have any introns
Bacterial DNA is housed in the _ and has _ shape
Bacterial DNA is housed in the cytoplasm and has circular shape
_ are elongated protein filament cylinders that are anchored inside the cell wall and plasma membrane (mostly of gram-negative bacteria)
Flagella are elongated protein filament cylinders that are anchored inside the cell wall and plasma membrane (mostly of gram-negative bacteria)
Flagella at one or both ends is called _
Flagella at one or both ends is called polar flagella
* Ex: psudomonas aeruginosa
Flagella that is all the way around is called _
Flagella that is all the way around is called peritrichous
* Ex: salmonella
Flagella help propel bacterium but they also can help in a regulator response called _
Flagella help propel bacterium but they also can help in a regulator response called chemotaxis
* Chemotaxis is movement towards or away from certain chemicals in the environment
_ appear as tiny hairs around a bacterium and they are more common in gram-negative species
Pili appear as tiny hairs around a bacterium and they are more common in gram-negative species
Two special functions of pili are _ and _
Two special functions of pili are adhesion and resistance
* Adhesions on the tips of pili allow bacterium to attach to surfaces in the environment
* R-pili are involved in drug resistance transfer via bacterial conjugation
The _ provides a barrier from the external environment, prevents osmolysis, and determines whether the bacteria will stain gram positive or negative
The cell envelope provides a barrier from the external environment, prevents osmolysis, and determines whether the bacteria will stain gram positive or negative
The capsule is a component of both gram-positive and negative bacteria and it is composed of _ and _
The capsule is a component of both gram-positive and negative bacteria and it is composed of glycoproteins and glycolipids
* Its main function is to defend against host immune responses
The outer (lipid) membrane is found in _ bacteria and is formed by a glycolipid layer which primarily contains _
The outer (lipid) membrane is found in gram-negative bacteria and is formed by a glycolipid layer which primarily contains lipopolysaccharide (LPS)
LPS is a _ disaccharide that forms a barrier to hydrophobic molecules
LPS is a glucosamine disaccharide that forms a barrier to hydrophobic molecules
* Contributes to the outer membrane’s selective permeability
The _ is a rigid structure made up of peptidoglycan; it forms a strong exoskeleton that helps to prevent lysis in hypotonic/isotonic solutions
The cell wall is a rigid structure made up of peptidoglycan; it forms a strong exoskeleton that helps to prevent lysis in hypotonic/isotonic solutions
* Both gram-positive and gram-negative have a cell wall
* If the peptidoglycan is damaged, the bacterium will lyse from the pressure of the internal cytoplasm
The cytoplasmic lipid membrane is similar to the cell membrane of eukaryotic cells, however, it does not contain _ (with the exception of mycoplasma)
The cytoplasmic lipid membrane is similar to the cell membrane of eukaryotic cells, however, it does not contain sterols (with the exception of mycoplasma)
* Both gram-positive and gram-negative have this
The outer membrane is only found in _ bacteria
The outer membrane is only found in gram-negative bacteria
Because _ bacteria don’t have an outer membrane, their cell walls are much thicker
Because gram-positive bacteria don’t have an outer membrane, their cell walls are much thicker
The thick gram-positive cell walls contain anionic polymers, _ and _ to provide reinforcement and structural integrity to the cell walls
The thick gram-positive cell walls contain anionic polymers, teichoic acids and lipoteichoic acids to provide reinforcement and structural integrity to the cell walls
In prokaryotes, the _ is simply all of the space within the cytoplasmic lipid membrane
In prokaryotes, the cytoplasm is simply all of the space within the cytoplasmic lipid membrane
The only structure found in prokaryote’s cytoplasm is _ ; and it is the area that contains the circular bacterial chromosome
The only structure found in prokaryote’s cytoplasm is nucleoid ; and it is the area that contains the circular bacterial chromosome
“Competent” bacteria have the ability to absorb naked DNA from the environment and integrate it into the bacterial chromosome via _
“Competent” bacteria have the ability to absorb naked DNA from the environment and integrate it into the bacterial chromosome via homologous recombination
Bacteria that must have oxygen to grow are called _
Bacteria that must have oxygen to grow are called obligate aerobes
Bacteria that cannot grow in the presence of oxygen are _
Bacteria that cannot grow in the presence of oxygen are obligate anaerobes
Bacteria that can grow with or without oxygen are called _
Bacteria that can grow with or without oxygen are called facultative anaerobes
* They can switch between states
Obligate anaerobes lack _ and _ which protect bacteria from oxygen free radicals
Obligate anaerobes lack superoxide dismutase and catalase which protect bacteria from oxygen free radicals
* Some antibiotics take advantage of this
Bacteria that only grow when specific nutrients are present (such as iron, CO2) are called _
Bacteria that only grow when specific nutrients are present (such as iron, CO2) are called fastidious bacteria
Pathogenic bacteria that require free iron for survival are capable of excreting _ compounds to bind iron and steal it from the blood and tissue proteins
Pathogenic bacteria that require free iron for survival are capable of excreting chelating compounds to bind iron and steal it from the blood and tissue proteins
* Chelating compounds are known as siderophores
Bacteria that cause human infections only replicate through _
Bacteria that cause human infections only replicate through binary fission
* The chromosome of a single bacterium is replicated –> division of the cytoplasm into two equal daughter cells
Some bacteria can transform into _ when they are in adverse conditions without nutrients; they become dormant, withstand harsh conditions, and become reactivated when the environment is more favorable
Some bacteria can transform into spores when they are in adverse conditions without nutrients; they become dormant, withstand harsh conditions, and become reactivated when the environment is more favorable –> called sporulation
* Example: bacillus, clostridium
Infants cannot have honey because they have immature digestive systems that can’t clear out the spores of _ that can contaminate honey
Infants cannot have honey because they have immature digestive systems that can’t clear out the spores of clostridium botulinum that can contaminate honey
* Spores can germinate and grow toxin-forming bacteria
* This is called infant botulism
* The first sign is usually constipation, then respiratory distress, lack of facial expression, drooling, muscle weakness can follow
In _ phase, bacteria mature and adapt to the growth environment; reproduction is slow
In lag phase, bacteria mature and adapt to the growth environment; reproduction is slow
_ is the period of rapid bacterial growth; the new cells created is proportional to the number of bacteria –> this phase continues until bacteria run out of resources
Exponential growth phase is the period of rapid bacterial growth; the new cells created is proportional to the number of bacteria –> this phase continues until bacteria run out of resources
When the bacteria runs out of nutrients, accumulates toxic waste, or runs out of space, it enters the _ phase
When the bacteria runs out of nutrients, accumulates toxic waste, or runs out of space, it enters the stationary phase
During the _ stage, the number of new bacteria appearing and dying is roughly the same
During the stationary stage, the number of new bacteria appearing and dying is roughly the same
The _ phase is when the bacterial population diminishes and eventually dies
The death phase is when the bacterial population diminishes and eventually dies
Bacterial infections in humans are measured in [unit]
Bacterial infections in humans are measured in colony forming units (CFUs)
acute infection
When stained, _ bacteria will appear purple/blue
When stained, gram-positive bacteria will appear purple/blue
* Their thick peptidoglycan cell walls retain the crystal violet die-iodine complex after the decolorizing step
* Ex: Staphylococcus
When stained, _ bacteria will appear pink
When stained, gram-negative bacteria will appear pink
* They only retain the safranin stain so they appear pink
* Ex: E.coli
Atypical bacteria are gram nonreactive and don’t retain any dye from the staining process; instead we must use _ staining
Atypical bacteria are gram nonreactive and don’t retain any dye from the staining process; instead we must use acid-fast staining
* Ex: Chlamydiaceae, Legionella, Mycobacteria, Nocardia
Acid-fast bacteria have large amounts of _ in their cell walls
Acid-fast bacteria have large amounts of mycolic acid in their cell walls
* Carbol fuchsin dye is used –> it dyes all cells, but once the cells are washed with acid alcohol, only acid-fast bacteria will be bright red
The most common method for endospore staining is _
The most common method for endospore staining is Schaeffer-Fulton method
* Bacteria is stained with malachite green (binds spores) then counterstained with safranin
* Spores will be green and bacteria pink
* Ex: Clostridium, bacillus (including B anthracis)
How do we visualize capsules?
Capsules do not bind to most dyes; we can stain the background with India ink or nigrosine –> then the bacteria can be counterstained
How does LPS activate systemic immune reactions?
LPS interacts with immune cell receptors –> leads to release of cytokines and inflammatory factors –> blood vessel dilation, increased permeability
_ are a more elongated coccobacillus, rod-shaped, like a hot dog
Bacillus are a more elongated coccobacillus, rod-shaped, like a hot dog
_ are spherical bacteria
Coccus are spherical bacteria
_ are an intermediate between cocci and bacilli that look like short rods/ ovals
Coccobacillus are an intermediate between cocci and bacilli that look like short rods/ ovals
_ are curved/ comma shaped
Vibrio are curved/ comma shaped
_ are wavy shaped bacteria
Spirillum are wavy shaped bacteria
_ are a twisted shape like the threads on a screw
Spirochete are a twisted shape like the threads on a screw
_ are bacteria that form pairs
Diploids are bacteria that form pairs
* ex: Neisseria
_ are bacteria that form short, single-file lines
Chains are bacteria that form short, single-file lines
* Streptococcus
_ are bacteria that bunch together like grapes
Clusters are bacteria that bunch together like grapes
* ex: Staphylococcus
_ are bacteria that form long thread-like filaments
Hyphae are bacteria that form long thread-like filaments
* ex: Nocardia
