Chapter 3 Flashcards by r l

Electron microscope can magnify _______x

How does it work?

100,000

Uses a beam of electrons

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Light microscope can magnify _____x

1,000

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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

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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

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Define Resolution (Resolving Power)

The ability to distinguish two different things

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Refractive index

Measures speed of light passing trough a medium

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Contrast

Determines how easily cells can be seen

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Why do we use immersion oil?

To displace air between lens and specimens which keeps the light focused on the specimens

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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

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What type of dye has a positive charge?

Basic dyes- they are attracted to negatively charged cellular components

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What type of dye has a negative charge?

Acidic dyes- cells repel so the background is colored.

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What are the 3 categories of stains?

Simple Stain
Differential Stain
Special Stain

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What are the characteristics of a Simple Stain?

-one dye is used to stain the cells

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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

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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

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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

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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

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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

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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

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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

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Why do antibiotics affect Gram Positive Cells more than Gram Negative Cells?

The outer membrane of Gram Neg Cells block passage of antibiotics.

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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.

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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

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What are the characteristics of a Capsule Stain?

negative stain

- capsules do not take to certain stains so they stand out against stained background

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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?

1. Copy DNA into one circular chromosome 2. Becomes enlarged 3. New cell wall begins to form 4. 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?

1. Bacillus 2. Staphylococcus 3. Streptococcus

What are the 3 representative genera of a Gram Negative Cell?

1. Escherichia 2. Neisseria 3. 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)??

1. Aquaporins (water channels) 2. Electron Transport System 3. Simple Diffusion 4. 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 1. Hypertonic 2. Hypotonic 3. 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

Chapter 3 Flashcards

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