Microbiology Exam 1 Flashcards
(93 cards)
1
Q
Different types of microorganisms
A
Prokaryotes: Bacteria and Archea
Eukaryotes: Algae, fungi, and protozoa
2
Q
What are some examples for prokaryotes?
A
Halophiles (Archaea) and E. coli (bacteria)
3
Q
What are some examples for eukaryotes?
A
Stentor
4
Q
Positive impacts of microbes during human history
A
yeast fermented food and beverages
“rock eating” bacteria helped with mining
5
Q
Negative impacts of microbes during human history
A
bubonic plauge causes by Yersinia pestis
Tuberculosis caused by mycobacterium tuberculosis
6
Q
Robert Hooke
A
developed the light microscope
7
Q
Antonie van Leeuwenhoek
A
First to see microbes under the microscope
8
Q
Francesco Redi
A
believed that maggots in decaying meat were offspring of files
9
Q
Lazzaro Spallanzani
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disproved spontaneous generation
10
Q
Louis Pasteur
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Performed the swan-necked flask experiment which showed that microbes would become trapped in the curve of the flask
11
Q
John Tyndall
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tipped the flask to allow the broth to reach the microbes which made the microbes multiplied quickly
12
Q
How did life orginated?
A
from chemicals
13
Q
Robert Koch
A
discovered M. Tuberculosis, growth of microbe in pure culture
14
Q
Koch’s Postulates
A
- the microbe is found in all cases of the disease
- The microbe is isolated from the diseased host and grown in pure culture
- When the microbe is introduced into a healthy, susceptible host, the same disease occurs.
- The same strain of microbe is obtained from the new diseased host
15
Q
What were some limitations from kochs postulates?
A
- difficulty in detecting the causative agents in some disease initially
- Absence of an animal host
- Difficulty to culture in laboratory conditions
16
Q
Lady Mary Wortley Montagu
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Discovered small pox in europe
17
Q
Dr. Edward Jenner
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invented vaccines for the small pox
18
Q
Ignaz Semmelweis
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Believed that hand washing with chlorine before surgery was a good antiseptic. lead to women dying when giving birth
19
Q
Joseph Lister
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Use of carbolic acid
20
Q
Alexander fleming
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Accidental discovery of penicillin
21
Q
Howard Florey and Ernst Chain
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1942 purified penicillin
22
Q
Dimitri Ivanosky and Martinus Beijerinck
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Tobacco Mosaic virus caused by “filterable agent”
23
Q
Magnification
A
Increase in the apparent size of an image
24
Q
Resolution
A
The smallest distance that two objects are separated, distinguished as separate objects
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Detection
Ability to determine the presence of the objects
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Coccus
Single coccus
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Diplococcus
Pair of two cocci
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Tetrad
Grouping of four cells arranged in a square
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Streptococcus
Chain of cocci
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Streptococcus
Chain of cocci
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Staphylococcus
Cluster of cocci
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Bacillus
Single rod
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Diplobacillus
Pair of rods
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Streptobacillus
Chain of rods
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Palisade
V or L shaped formation of rods
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Absorption
The object blocks part of the light
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Reflection
The wavefront of the light bounces off the surface
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Refraction
The light bends when it enters a substance that changes its speed
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Scattering
A small fraction of the incident light is scattered in all directions. Object size is near incident wavelength
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Interference
The interaction of two wavefronts (additive or subtractive)
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Parabolic lens
bends light rays to intersect at a focal point, light rays bend and spread
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For proper resolution
- the contrast between the object and its surrounding
- wavelength smaller than the object
- magnififcation
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Bright field microscopy
- Wavelength and resolution
-light and contrast
- lens quality
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Oil immersion
More light is collected and the resolution improves
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Phase contrast microscopy
-use refraction and interference caused by structures in a specimen to create high-contrast, high-resolution images without staining.
-Exploits difference in refractive index between cytoplasm, surrounding medium, different organelles
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Phase contract microscopy application
object or specimen refracts or reflects light, light that travels from the condenser lens and the light travel through the species are out of phase when passing through the objective and phase length.
-Wavelengths in phase or out of phase either add together or
cancel out each other.
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Simple staining
One type of stain
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Basic stains
-uses methylene blue, crystal violet, and safranin
- Stains negatively charged molecules and structures
- comes out as positive
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Acidic Stains
-Uses Esoin, acid fuchsin, and congo red
- Stains positively charged molecules and structures such as proteins
- Can either be positive or negative
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Negative strains
- Uses india ink and nigrosin
- Stains the background, not the specimen
- It shows a dark background but with a light specimen
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Differential stain
Two types of stains; gram stains
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Gram Stain
- Uses crystal violet, grams iodine, ethanol, and safranin
- Used to distinguish cells by the cell wall type
- can either be gram positive (purple) or gram-negative (pink)
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Acid-fast stain
- After staining with basic fuchsin, acid-fast bacteria resist decolorization by acid alcohol.
- Used to distinguish acid-fast bacteria
- Acid fast is red and non acid fast is blue
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Endospore stain
-Uses heat to stain endospores with malachite green then the cell is washed and counterstained with safranin
- Used to distinguish organisms with endospores from those without
- Endospores come out bluish-green and others come out pink or red
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Flagella stain
Flagella are coated with a tannic acid or potassium alum mordant and then stained using either para rosaline or basic fusion
- used to view and study flagella
- flagella are visible if present
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Capsule stain
Negative staining with india ink or nigrosin is used to stain background
- Used to distinguish cells with capsukes
- Capsules appear clear or as halos if present
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the purpose of gram stain
to determine is a bacteria is gram-positive or gram-negative based off their cell wall
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The steps of gram staining
1. Add methanol to fixed cells, and allow to air dry
2. Add C. Violet for one minute
3. Add iodine, this binds the stain to the gram-positive cells
4. wash with ethanol for ten seconds
5 add safranin for 1 minue
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Fluorescence microscopy
uses fluorescent chromophores called fluorochromes, which are capable of absorbing energy from a light source and then emitting this energy as visible light.
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Fluorophores
- chemical affinity: binds to certain molecules
- labeled antibodies
- DNA hybridization: Tags DNA, binds w complementary strand
- gene fusion reporter: targets certain genes, if the gene transcribe it will be red, the others will be red
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excitation and emission
1. energy of UV proton is absorbed by electron
2. Electron is raised to orbital of higher energy
3. Electron loses some energy and drops to slightly lower orbital
4. fluorescence is emitted at longer wavelength
5. electron returns to orginal level
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Confocal laser scanning microscopy
uses a laser to scan multiple z planes
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Fluorescence in Situ Hybridization (FISH)
1. Cells are fixed to a slide and are permeabilized
2. fluorophore-labeled DNA probed hybridized to rRNA
3. Unbound probe molecules are washed away
4. Cells containing hybridized probes are identified and enumerated by fluorescence microscope
- Localizes where the microorganism is at on slide
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Transmission electron microscope
it uses an electron beam from above the specimen that is focused using a magnetic lens (rather than a glass lens) and projected through the specimen onto a detector. Electrons pass through the specimen, and then the detector captures the image
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Scanning electron microscope
form images of surfaces of specimens, usually from electrons that are knocked off of specimens by a beam of electrons. This can create highly detailed images with a three-dimensional appearance that are displayed on a monitor
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similarities and difference of prokaryotic and eukaryotic cells
Similarities: Lipid bilayer, DNA, cytoplasm, and ribosomes
Differences: cell size, Eukaryotes have nucleus and prokaryotes dont, Eukaryotic dna is linear, prokaryotes dna is circular
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Difference in cell membrane structure between bacteria and archea
Bacteria: Lipid bilayer
Archea: lipid bilayer or monolayer
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The difference in cell wall structure between gram-positive and gram-negative bacteria
- Gram-positive cell walls are structurally simple, containing a thick layer of peptidoglycan with embedded teichoic acid external to the plasma membrane.
- Gram-negative cell walls are structurally more complex, containing a thin layer of peptidoglycan and an outer membrane containing lipopolysaccharide.
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Mycobacterial cell wall structure
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function of S layer
- found in gram negative and postive bacteria
- Helps in defense against phages and predators
- protein subunits fits like tiles
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Capsule
- found in gram negative and positive bacteria
- defense against phagocytosis
-polysaccharide
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Components of gram- negative outer membrane and their functions
lipoprotein. The outer leaflet of the outer membrane contains the molecule lipopolysaccharide (LPS), which functions as an endotoxin in infections involving
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Common cytoskeleton in bacteria
-FtsZ: cell diameter maintenance and formation of Z-ring
-MreB: required of elongation
-Crescentin
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How does the DNA replication process regulates bacterial cell division?
- Dna origin replicates and migrates
- Dna replication continues bidirectionally
- Dna starts next round
- Septum forms ( completion of replication triggers Z- ring formation)
- Division into two cells
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Cell asymmetry in bacteria and their role in bacterial survival
enables endospore formation and allows survival in hard conditions
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What are the roles of the membrane extension in bacteria?
Cell extension expands the cells reach of scarce nutrients but the function os the extensions is unclear
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What is the role of nanotubes in bacteria?
enables bacteria to share proteins and mRNA that encode product useful under hostile conditions
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Thylakoids: cyanobacteria (phototrops)
Extensively folded intracellular membrane
- maximize the collecting area of their photosynthetic membranes
- conduct light reactions
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Carboxysomes
Protein covered bodies packed with enzyme rubisco of CO2 fixation
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Gas vesicles
Increases buoyancy and keeps cell afloat
- enables the phtotrophs to remain at the surface of the water, exposed to light
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Storage granules
energy rich materials ; utilized during scarcity of light
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Sulfur granules
produced through photolysis of hydrogen sulfide
- used as an oxidant when reduced substrates are avaliable
- presence of toxic sulfur granules help cells avoid predation
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Pili
common adherence structure, made of pilin
- short attachment pili are called fimbriae
- helps to attach to host cells and provide twitching motility to bacteria
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Sex pili
for conjugation between bacteria ( DNA transfer)
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Stalk
Secerts adhesion factors that for a "hold fast"
- firmly attaches the bacterium in favorable environment
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Rotary flagella
motility
- monotrichous: one tail
- amphitrichous: two tails
- lophotrichous: four tails
- peritrichous: multiple tails
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Filament of Rotary flagella
Helical screw, made of flagellin
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Hook of Rotary flagella
universal joint; connects filament and body
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Basal body of Rotary flagella
reversible rotary motor
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Flagellar rotation of Rotary flagella
driven by the cells transmembrane proton current
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Bacterial movement in response to chemical stimuli
-Without chemical stimuli, the flagellar rotates between counter-clockwise (run) and clockwise (tumble) with no overall directional movement.
- with chemical stimuli, the length of runs is extended, while the length of tumbles is decreased. this leads to chemotaxis, the overall directional movement toward the higher concentration of the attractant
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How do bacterial cells decide to swim?
chemotaxis: the ability of organisms to move toward or away from specific chemicals
93
What drives rotation of the flagellar motor?
H+ flows through MotA-MotB complex (basal body)
