Exam 1 - Part 2 Flashcards
Chapters 3-5, 7 Bacterial, Archaeal, Eukaryotic structure, and Bacterial and Archaeal Growth
what makes an endospore so resistant?
- calcium complexed with dipicolinic acid
- small acid-soluble DNA-binding proteins
- dehydrated core
- spore coat
- DNA repair enzymes
hypertonic solution
solute concentration is higher outside of cell than inside, water moves out of cell
colony
visible growth or cluster of microorganisms
what environmental conditions are bacterial endospores resistant to?
- heat
- radiation
- chemicals
- desiccation
the charge gradient
when the cell membrane holds back protons it also holds back a charge thus generating proton motive force which creates dual energy
psychrotroph
prefer to grow in lower temps but can grow in higher temps than psychrophiles
- involved in food spoilage
what is the virulence facor?
a tool or mechanism that a bacteria has to cause disease
integral proteins
embedded within the membrane and not easily removed
facilitated diffusion
- solute combines with a transporter protein in the membrane
- transport ions ad larger molecules across a membrane with the concentration gradient
active transport
- uniport/symport/antiport
- energy dependent transport
- can work against the concentration gradient
- used to concentrate 1000X greater than outside
- uses proton motive force (PMF) as energy source
cilia
short projections, found in eukaryotes
electron microscopes
mechanism: uses electron beams in place of visible light to produce the magnified image
uses: can clearly see images 100,000x
capsule stain
because the viscous capsule does not readily take stains
differential stains
distinguished one group of microorganisms from another
do polar molecules move freely across the membrane? what can move across the membrane?
- no, with the exception of water
- fat soluble molecules
- hopanoids (steroids like cholesterol)
confocal microscopy
- cells are stained with fluorochrome dyes
- generate images of a simple plane of a specimen
- each plane in a specimen is illuminated and a three-dimensional image is constructed with a computer
- can examine layer of cells to a depth of 100 micrometer
- laser beam, very sharp images, can see different angles and 3D images
- explains phagocytosis
- fluorescent dyes to see antibodies
what is the mechanism of action of EMB agar?
two dyes, eosin Y and methylene blue, inhibit the growth of gram + bacteria. they also react with acidic products released by certain gram - bacteria when they use lactose or sucrose as carbon and energy source. colonies of gram - bacteria that produce large amounts of acidic products have green, metallic sheen
what is the functional type of MacConkey (MAC) agar?
selective and differential
confocal microscope
mechanism: mirrors scan a laser beam across successive regions and plans of a specimen. from that data, a computer constructs an image
uses: used to construct a three dimensional image structure, provides detailed sectional views of intact cells
flagella stain
the staining agent adheres to and coats the otherwise thin flagella, enabling them to be seen with the light microscope
psychrophile
prefers low temps
active transport
requires a transporter protein and ATP, goes against gradient
prokaryotic nucleoid
localization of genetic material (DNA)
what is the difference in eukaryotic chromosomes versus prokaryotic?
- multiple and are enclosed
- bacteria only have one set but has extra in plasmids
- euks have chloroplasts and mitochondria
transmission electron microscope (TEM)
mechanism: transmits a beam of electrons through a specimen
uses: elaborate specimen preparation, which may introduce artifacts, is required
- section specimen into thin sections - cross section, enables viewer to see the details inside
atomic force
mechanism: a tip bends in response to even the slightest force
uses: can operate in air and in liquids
faculative anaerobes
- both aerobic and anaerobic growth, greater growth in the presence of oxygen
- growth is best where most oxygen is present but occurs throughout the tube
- has SOD and catalase
flourscence
- mechanism: projects ultraviolet light, causing fluorescent molecules in e specimen to emit longer wavelength light
uses: used to observe cells that have been stained or tagged with florescent dye - used as a diagnostic tool
mechanism of flagellar movement
- flagellum rotates like a propeller
- counterclockwise rotation causes forward motion (run)
- clockwise rotation disrupts run, causing a tumble
what are capsules?
- usually composed of polysaccharides
- well organized and nor easily removed from cell
- helps prevent phagocytosis (immune system kills bacteria)
osmosis
- the movement of water across a selectively permeable membrane from an area of high water to an area of lower water concetration
- through lipid layer in aquaporins (water channels)
sex pili
- similar to fimbriae except longer, thicker, and less numerous
- required for mating
endospore stain
stains endospores, a type of dominant cell that does not readily take up stains, these are produced by the genera bacillus and clostridium
what is germination in endospores?
germination, takes it back to vegetative state
simple diffusion
- movement of a solute from an area of high concentration to an area of low concentration
- continues until molecules reach equilibrium
selective media
- a media that allows one group of microbes to grow and inhibits another
- add nutrients and chemicals that prevent the growth of one group over another
Biosafety Level 2
lab coat, gloves, eye protection
prokaryotic cell wall
gives prokaryotes shape and protection from osmotic stress
effects of NaCl on growth
- halophiles: grow optimally at >.2 M
- extreme halophiles: require > 2 M
group translocation
- the phosphotransferase system (PTS)
- the nutrient is chemically altered
prokaryotic endospore
survival under harsh environmental conditions
prokaryotic cell wall
- rigid structure outside the plasma membrane
- protects the cell from osmotic lysis
- very few prokaryotes lack cell walls
- composed of mesh-like polymer composed of N-acetylglucosamine and N-acetylmuramic acid
- peptidoglycan subunits are cross-linked by peptides
- gram + has 25 layers, gram - has 5 layers
- penicillin inhibits peptidoglycan synthesis
- cell wall usually consists of complex polysaccharides
- some archaea have walls made of pseudomurein
what makes plasmids so special?
- small piece of DNA - extra chromosomes
- carry genes for antibiotic resistance and disease causing genes
- these genes can be shared through pili and given to other bacteria through conjugation
defined/synthetic media:
- everything is known in terms of grams (like carbon or nitrogen)
- measure everything specifically
- pH is not controlled
uniporter
- active transport
- one substance is transported
Biosafety Level 4
sealed, negative pressure
-exhaust air is filtered twice through HEPA filters
how is fluorescent microscopy used as a diagnostic tool?
- antibody is used to find the bacteria
- fluorescent dye is added to the end of an antibody tail, which transfers to the bacteria and is able to track it
thermophiles
can grow in boiling temps
what is the universal principle life is based on?
the specific interaction of molecules with each other. interacting molecules interact as pairs called ligand and receptor
pure culture
population of cells arising from a single cell
what outer structure does eukaryotes have but prokaryotes do not?
- cilia
- bacteria have pili and fimbriae
what are most human pathogens?
mesophiles
antiporter
active transport
-one substance is transported in as a different one exists
prokaryotic gas vacuole
buoyancy for floating in aquatic environments
what are slime layers?
similar to capsules except it diffuses, it is unorganized and easily removed
prokaryotic capsules and slime layers
resistance to phagocytosis, adherence to surfaces
- made of proteins or polysaccharides
prokaryotic fimbriae and pili
attachment to surfaces, bacterial mating
what are the systems used to move nutrients and water products across the membrane?
- facilitated diffusion
- active transport
- group translocation
phase-contrast
mechanism: amplifies differences in refractive index to create contrast
uses: makes unstained cells more readily visible
- based off of the density of different cellular components. can use dyes to see the densities in different colors
differential media
- media that differentiates one growth from another
- if there are two organisms growing, they will be two different colors
- this is based off pH bc it is a pH indicator
integral proteins
embedded within the membrane and not easily removed
what is the functional type of mannitol salt agar?
selective and differential
bright-field
mechanism: illuminates the field of view evenly
uses: most common type of microscope
what are the by products of oxygen? what can help prevent this?
- peroxide, superoxide, and free radicals
- catalyse and SOD (superoxide dismutase)
What are the types of bacteria that produce endospores? what diseases do they cause?
- Clostridium, *gangrene, *botulism, tetanus, CDAD
- Bacillus - anthrax, food poisoning
interferences
mechanism: two light beams pass through the specimen and then recombine
uses: causes the specimen to appear as a three-dimensional image
the growth curve
-observed when microorganisms are cultivated in batch culture
(batch = culture incubated in a closed vessel with a single batch of medium )
-usually plotted as logarithm of cell number versus time
measurement of cell numbers: viable cell counts
- plating methods
- membrane filtration methods
special stains
stains specific structures inside or outside of cell
AHL
acylhomerine lactone. an auto-inducer molecule produced by many gram negative organisms
- concentration present allows cells to access population density
- apart of quorum sensing
hypotonic solution
solute concentration is lower outside than inside the cell, water moves into cell
simple stains
employs a basic dye to impart a color to a cell, easy way to increase the contrast between otherwise colorless cells and a transparent background
common macroelements of culture media
C, O, H, N, S, P, K, Ca, MG, Fe
common micronutrients of culture media
Mn, Zn, Co, Mo, Ni, and Cu
what color does acid-fast stain?
red cells are acid fast, blue cells are non-acid fast
the plasma membrane
- phospholipid bilayer that encloses the cytoplasm
- peripheral proteins on the membrane surface
- integral and transmembrane proteins penetrate the membrane
measurement of cell numbers: direct cell counts
- counting chambers
- electronic counters
- on membrane filters
prokaryotic flagella
movement
gram positive cell walls
- thick peptidoglycan
- teichoic acids link cell wall to plasma membrane
- 25 layers
Biosafety Level 3
biosafety cabinets to prevent airborne transmission
differences between prokaryotic and eukaryotic cells
- prokaryotic cells lack membrane-enclosed organelles (including a nucleus)
- peptidoglycan is found only in prokaryotes
- endospores only found in prokaryotes
symporter
active transport
-two different substances are transported at the same time and in the same direction
prokaryotes cell overview
- one circular chromosome, not in a membrane
- no histones
- no organelles
- divides by binary fission
isotonic solution
solute concentrations equal inside and outside of cell, water is at equilibrium
gram stain
used to separate bacteria into two major groups, gram-positive and gram-negative. The staining characteristics of these groups reflect a fundamental difference in the chemical structure of their cell walls, this is by far the most widely used staining procedure
facilitated diffusion
- interaction between diffusion facilitator protein and nutrient molecules
- specific binding of nutrient to facilitator protein
- conformational change in facilitator protein
- release of nutrients into the cytoplasm of the cell until equilibrium is met
mycobacteria
- waxy thick shell wall, made of lipids, can’t pick up the gram stain, have to use acid fast
- TB and leprosy
what color does gram stain?
purple cells are gram positive and red cells are gram negative
what are fimbriae?
- short, thin, hairlike proteinaceous appendages
- mediate attachment to surfaces
- some (type IV fimbriae) are required for twitching motility or gliding motility that occurs in some bacteria
transmembrane protein
- spans across the cell membrane and shows up on either end of the cell wall
- functions as a carrier, receptor, and signal transduction (start/stop chemical reactions)
biofilms
- ubiquitous in nature
- complex, slime enclosed colonies attached to surfaces
- form on medical devices such as implants often leading to illness
- microbes reversibly attach to conditioned surface and release polysaccharides, proteins, and DNA bio-film
- interactions occur among the attached organisms
- extracellular matric and change in attached organisms protects them from UV light and antibiotics
- sloughing off of organisms results in contamination of surroundings
- bacteria sticks to the surface and on top of one another and communicate with one another to release proteins and polysaccharides
what is the functional type of eosin methylene blue (EMB) agar?
selective and differential
transmission
higher the number of bacteria, lower the transmission
prokaryotic plasma membrane
selectively permeable barrier, mechanical boundary of cell, nutrient and waste transport, location of many metabolic processes, detection of environmental cues for chemotaxis
auto-inducer
- produces chemicals that penetrate into other cells around them
- triggers gene expression for a specific molecules
light microscope
mechanism: visible light passes through a series of lenses to produce a magnified image
uses: relativly easy to use, considerably less expensive than confocal and electron microscope
what are the cell walls made of in bacteria? archaea?
- peptidoglycan
- pseudomurein
Biosafety Level 1
no special precautions, basic teaching labs
obligate anaerobes
- only aerobic growth, growth ceases in presence of oxygen
- has SOD, may or may not have catalase
chemotaxis
- repelling or moving away from a toxic molecule
- go through tumble and run to move away or towards things in the environment
what cannot penetrate biofilms?
antibodies and antibiotics
what is the functional type of a blood agar medium
enriched and differential
peripheral proteins
loosely associated with the membrane and easily removed
what are the uses of materials that lie outside the cell wall? (external cell wall)
- protect against host immune system
- protects against harsh environment
- facilitates attachment to surfaces
- facilitates motility of gliding bacteria
what is the glycocalyx?
- network of polysaccharides extending from the surface of the cell
- a capsule or slime layer composed of polysaccharides can also be referred to as a glycocalyx
the membrane
the key barrier between the cell and the outside world. mainly composed of lipids and proteins
compare the sizes of microbes
- viruses: nm
- bacteria: mm
- animal cell: tens of mm
flourescence microscopy
- uses UV light
- fluorescent substances absorb UV light and emit visible light
- cells may be stained with fluorescent dyes (fluorochromes)
- diagnostic microscopy
culture media
- most contain all the nutrients required by the organism for growth
- defined or synthetic
- complex
- selective
- differential
prokaryotic cell membranes
- absolute requirement for all living organisms
- encompasses the cytoplasm
- some prokaryotes have internal membrane system
- separates cell from its environment
- selectively permeable barrier
- transport systems aid in movement of molecules
- location of crucial metabolic processes
- detection of and response to chemicals in surroundings with the aid f special receptor molecules in the membrane
- crucial metabolic processes like ETC
complex media
- plant, animal, or bacteria extracts that are dehydrated ground up as foods for microbes to grow
- don’t have to measure the extracts
- pH is controlled
obligate aerobes
- only aerobic growth, oxygen required
- growth occurs only where high concentrations of oxygen have diffused into the medium
- has SOD and catalase
scanning electron microscope (SEM)
mechanism: a beam of electrons scans back and forth over the surface of the specimen
uses: used for observing surface details, produces a three-dimensional effect
- specimen stay intact, see outer structure, but no inside details
similarities between prokaryotic and eukaryotic cells
- similar polymers
- carry similar chemical reactions
- both have ribosomes
- both may or may not have a cell wall
- similar cell membranes
absorption
higher number of bacteria, higher the absorption
- also depends on OD, the higher the OD, the higher the number of absorption and cells
bacterial endospores
- formed by some bacteria
- dormant
group translocation
requires a transporter protein and phosphoenolpyruvic acid (PEP), substance is altered as it crosses the membrane
dark-field
mechanism: light is directed toward the specimen at an angle
uses: makes unstained cells more readily visible, organisms stand our as bright objects against a dark background
flagella
long projections found in both eukaryotes and eukaryotes
effects of pH on growth
-acidophiles’ alkalophiles withstand high/low pH
-most maintain an internal pH near neutrality
-the plasma membrane is
impermeable to protons
-some synthesize
protective proteins
-many change pH of their habitat by producing acidic/basic products
aerotolerant anaerobes
- only anaerobic growth, but growth continues in presence of oxygen
- growth occurs evenly, oxygen has no effect
endosymbiotic theory
- larger bacterial cells engulfed smaller bacterial cells, developing the first eukaryotes
- ingested photosynthetic bacteria became chloroplasts
- ingested aerobic bacteria became mitochondria
what are some examples of an external cell wall?
- glycocalyx
- capsules
- slime layers
- S-layers
eukaryote cell overview
- paired chromosomes
- histones
- organelles
- divides by mitosis
pili and fimbriae
short projections, found in prokaryotes
what is the mechanism of action of mannitol salt agar?
a concentration of 7.5% NaCl selects for the growth of staphylococci. pathogenic staphylococci can be differentiated based on the release of acidic products when they use mannitol as a carbon and energy source. the acidic products caused a pH indicator (phenol red) in the medium to turn yellow
acid-fast stain
used to detect members of the genus mycobacterium in a specimen. due to the lipid composition of their cell walls these organisms do not readily take up stains
- detects mycobacteria to see TB and leprosy
what are S-layers?
- regularly structured layers of protein or glycoprotein
- more common among archaea (protects against osmotic stress
how are acidophiles able to survive such high pH levels?
because they can remain neutral by not allowing protons to enter through the plasma membrane.
- no matter what the environment is, the inside of the bacterial cell is neutral
what is the mechanism of action of a blood agar medium?
supports the growth of many fastidious bacteria. these can be differentiated based on their ability to produce hemolysis - protein that lyse red blood cells. hemolysis appears as a clear zone or greenish halo around the colony
compare gram positive and negative on the following:
- outermembrane
- LPS
- teichoic acid
- lysozyme
- penicillin G
- sensitivity to complement
- outermembrane: absent in G+, present in G-
- LPS: absent in G+, present in G-
- teichoic acid: present in G+, absent in G-
- lysozyme: high in G+, low in G-
- penicillin: easy in G+, difficult in G-
- complement: low in G+, high in G-
what is quorum sensing?
- AHL or other signal molecule diffuses across plasma membrane
- at high concentrations it enters the cell
- once inside the cell, it induces expression of target genes that regulate a variety of functions
prokaryotic periplasmic space
contains hydrolytic enzymes and binding proteins for nutrient processing and uptake
how resistant are biofilms to microbicides? what percentage is biofilms involved in infection? what kinds of infections?
- 1000X
- 70%
- catheters, heart valves, contact lenses, and dental carries
what is the mechanism of action of MAC agar?
the selective components of MAC are bile salts and crystal violet, which inhibit the growth of gram + bacteria. the presence of lactose and neutral red, a pH indicator, allows the differentiation of gram - bacteria based on the products released when they used lactose as a carbon energy sources. the colonies of those that releases acidic products are red
what are the cardinal growth factors?
minimum, optimal, and maximum
what are the four distinct phases of the growth curve?
- lag phase
- log phase
- stationary phase
- death phase
when did life arise as simple organisms?
3.5-4 billion years ago
where does the energy for PTS come from?
- PEP from glycolysis, from group translocation
- glucose becomes glucose - 6 - phosphate
when did the first eukaryote evolve?
2.5 billion years ago
gram negative cell walls
- thin peptidoglycan
- outer membrane
- periplasmic space
- 5 layers
prokaryotic inclusion bodies
storage of carbon, phosphate, and other substances
