Chapter 3 Flashcards
Electron microscope can magnify _______x
How does it work?
100,000
Uses a beam of electrons
Light microscope can magnify _____x
1,000
When viewed using a microscope, the object is magnified by a factor equal to the product of the magnifying powers of the ______ & the ______.
Objective lens & Ocular lens
The total magnification is the product of…?
The product of the magnifying power of the ocular lens and the objective lens.
Ex.
10x X 10x = 100x magnification
40x X 10x = 400x magnification
Define Resolution (Resolving Power)
The ability to distinguish two different things
Refractive index
Measures speed of light passing trough a medium
Contrast
Determines how easily cells can be seen
Why do we use immersion oil?
To displace air between lens and specimens which keeps the light focused on the specimens
What is involved in making a smear?
- air drying a liquid that has been placed in a glass slide
- spreading a thin film of specimens on a class slide
What type of dye has a positive charge?
Basic dyes- they are attracted to negatively charged cellular components
What type of dye has a negative charge?
Acidic dyes- cells repel so the background is colored.
What are the 3 categories of stains?
- Simple Stain
- Differential Stain
- Special Stain
What are the characteristics of a Simple Stain?
-one dye is used to stain the cells
What are the characteristics of a Differential Stain?
What are the 2 main types?
-2 separate dyes are used to distinguish one group of microorganisms from another.
- Gram Stain
- Acid-Fast Stain
What are the characteristics of a Special Stain?
What are the 3 main types?
-used to stain specific structures inside or outside of cells
- Capsule Stain
- Endoscope Stain
- Flagella Stain
Characteristics of a Gram Stain:
What are the 2 types?
-used to separate bacteria by the thickness of their cell wall
- Gram Positive Stain
- Gram Negative Stain
What are the 4 steps in creating a Gram Stain?
- Crystal Violet Stain
- all cells are purple in color
- Iodine (mordant)
- all cells remain purple
- Alcohol (decolorizer)
- gram+ purple / gram- colorless
- Safranin (counterstain)
- gram+ purple / gram- pink
7 Characteristics of Gram Positive Cells:
- thick cell wall
- Teichoic Acid present
- slightly negative charge
- no outer membrane
- no LPS (lipopolysaccharide)
- affected by antibiotics
- not affected by lysozyme
7 Characteristics of Gram Negative Cell:
- thin cell wall
- no Teichoic Acid
- outer membrane present
- slightly positive charge
- LPS (lipopolysaccharide) present
- not affected by antibiotics
- affected by Lysozyme
Characteristics of LPS (lipopolysaccharide) in Gram Negative Cell?
Where is it located within the cell?
- also called endotoxin
- signals immune system of invasion
- contains O antigen & Lipid A
-within the outer membrane
Why do antibiotics affect Gram Positive Cells more than Gram Negative Cells?
The outer membrane of Gram Neg Cells block passage of antibiotics.
Why do Lysozyme affect Gram Negative Cells more than Gram Positive Cells?
Lysozyme interferes with the cell wall synthesis, and because the Gram Neg has a thin cell wall it is easily penetrated.
What are the Characteristics of an Acid-Fast Stain?
- used to detect Myobacterium
- does not take stain well because of waxy fatty acid cell wall
- contains mycolic acid
What are the characteristics of a Capsule Stain?
- negative stain
- capsules do not take to certain stains so they stand out against stained background
What are the characteristics of an Endospore Stain?
- stains endospores
- heat is used to facilitate uptake of primary dye
- counter stain used to visualize other cells
Characteristics of a Flagella Stain:
-stain coats the flagella to make it thicker and easier to see
What is the difference between Bacillus & bacillus????
Bacillus- group
bacillus- rod-shaped
Can you tell if a cell is Gram Pos or Gram Neg by doing a special stain??
No.
Coccus
Spherical shape
Rod
Cylindrical shape
Coccobacilla
Oval shaped
Diplococci
2 spherical cells combined
Streptococci
Chain of spherical cells
Vibro
U shaped
Spirillium
Wavy shaped
Spirochete
Spiral shaped
Staphylococcus
Cluster of circular cells
How do most prokaryotes devide?
Binary fission
Internal structures of a Prokaryotic Cell?
- ribosomes
- endospores
- plasmids
- storage granules
- chromosomes
External structures of Prokaryotic Cells?
- flagella
- pili
- capsule
- slime layer
- cell wall
- gram positive
- gram negative
Steps of Binary Fission?
- Copy DNA into one circular chromosome
- Becomes enlarged
- New cell wall begins to form
- Asexual (no new production)
Function of Ribosomes?
Synthesize proteins
Plasmids function/characteristics:
- carries non-essential genes
- extra chromosomal DNA molecule
Pili function:
-allow cells to adhere to surfaces and potentially cause diseases
Capsule function/characteristics:
- allows bacteria to adhere to surfaces and potentially cause diseases
- protects cell
- distinct edges
- gelatinous (fairly solid)
What are capsules and slime layers typically made of?
Give an example:
Glycocalyx- an extra cellular polysaccharide coating
Ex. Dental plaque
Chromosome function:
Carries genetic information of a cell
Where is the periplasmic space located?
What does it consist of?
Between the cytoplasmic membrane and the outer membrane.
Filled with gel-like periplasm rich in proteins
What structures of a cell have Virulence? And what does it mean?
Pili & capsule
It is a trait that leads to pathogenicity
Cell Wall functions:
- prevents cell lysis
- prevents destruction w/ changes in osmotic pressure
- prevents cell from bursting
What makes up a cell wall?
Peptidoglycan
Why is peptidoglycan sensitive to penicillin?
Penicillin interfered with peptidoglycan synthesis
What is peptidoglycan made up of?
amino acids, polysaccharides, and polypeptides.
What is lysis?
When lysozyme breaks the bonds that link subunits of peptidoglycan apart.
What are the 3 representative genera of a Gram Positive Cell?
- Bacillus
- Staphylococcus
- Streptococcus
What are the 3 representative genera of a Gram Negative Cell?
- Escherichia
- Neisseria
- Pseudomonas
Cytoplasmic Membrane functions:
- serves as a semipermeable membrane
- barrier between interior and exterior of cell
What is the cytoplasmic membrane made up of?
Phospholipid bilayer
What can pass FREELY through the cytoplasmic membrane?
- hydrophobic molecules
- non polar molecules
- water
What are 4 other ways molecules can pass through the cytoplasmic membrane (lipid bilayer)??
- Aquaporins (water channels)
- Electron Transport System
- Simple Diffusion
- Osmosis
Electron Transport Chain funtions:
- allows nutrients to enter and leave the cell
- converts energy into ATP
- creates electrochemical gradient across the membrane
What is Active Transport?
Give 2 examples
- cell is using energy to transport molecules in/out
- movement against the gradient
Ex. The use of ATP & proton motive force
What is Passive transport?
Give an example:
- cell is not using energy to pass in/out
- going with the grain
Ex. Facilitated diffusion
Simple Diffusion
Movement from high to low concentration
Osmosis
Name 3 types
Diffusion of water across a selectively permeable membrane due to unequal solute concentrations
- Hypertonic
- Hypotonic
- Isotonic
Hypertonic
- higher concentration of dilutes outside the cell
- net movement of water OUT of the cell
- shrivels up
Hypotonic
- higher concentration of solutes inside the cell
- net movement of water INTO the cell
- cell expands
Where is a Lysozyme found?
Tears, saliva, & other bodily fluids
What part of the cell is stained with crystal violet?
Inside of cell
The gram+ cell wall prevents crystal violet-iodine complex from being washed out
What type of bacteria lack a cell wall?
Where does it get its strength from?
Mycoplasma species
Shape varies and uses sterol to increase strength
What is another example of a cell appendage other than flagella?
Chemotaxis- bacteria sense chemicals and move accordingly in a series of runs and tumbles
What cell is larger, Eukaryotic or prokaryotic?
Eukaryotic cells
Isotonic
- equal concentration of solutes in/out of cell
- net movement of water is stationary
What happens to a cell when it is exposed to a hypotonic solution?
The cell may lyse (destruction of cell)
Flagella function/characteristics:
-involved in motility of prokaryotic cells
Ex. Peritrichous- covered entirely in flagella
Endospore characteristics:
- member of Bacillus & Clostridium groups
- dormant cell
- resistant to heat, chemicals, boo lining water, disinfectant, ultraviolet light ect
