Micro Bio > Structures, Staining, and Taxonomy > Flashcards

Structures, Staining, and Taxonomy Flashcards

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1
Q

Describe the Structure of Bacteria from outside In

A

Appendages –> Surface and cell wall –> Cytoplasm –> Other structures

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2
Q

What does the Appendages consist of

A

– flagella
– fimbriae
– pili

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3
Q

What does the Surface and cell wall consist of

A

– capsule
– cell wall
– cell membrane

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4
Q

What does the Cytoplasm consist of

A

– chromosome
– plasmids
– ribosomes
– inclusions

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5
Q

What does the Other structures consist of

A

– endospores

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6
Q

What are appendages

A

projections from the cell

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7
Q

What is Flagella

A

– Long slender, whip like, structured made of protein

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8
Q

What does flagella do

A

– Enables the bacteria to move by rotating like a
propeller

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9
Q

How are flagella seen

A

Can only be seen using special stains or electron
microscopy

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10
Q

Describe monotrichous

A

a single flagella

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11
Q

Describe peritrichous

A

multiple flagella or located in tuffs or all around the cell

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12
Q

What are Fimbraie

A

Shorter, thinner filaments made of protein

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13
Q

What does Fimbraie enable

A

Enable bacteria to attach to substances

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14
Q

what are Pili

A

Similar to fimbriae in structure

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15
Q

What does Pili allow

A

Involved in transfer of DNA between bacteria

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16
Q

What is the capsule

A

A shell made from materials secreted by bacteria that cover the exterior of the cell

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17
Q

Describe the 2 characteristics of the capsule

A

– Often polysaccharide (sugary substance that prevents phagocytosis)
– May be a thick layer; slime coating

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18
Q

What is the function of the cell wall in bacteria

A

– Maintains cell shape and integrity

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19
Q

What is the Cell wall of bacteria made of

A

– A strong layer made of peptidoglycan

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20
Q

Why is the cell wall important when it comes to antibiotics

A

A principle target for antibiotic action. If you destroy cell wall bacteria will loose shape etc.

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21
Q

What does the cell wall stain with

A

– Stains using the Gram stain
– Differs for Gram positive vs Gram negative organisms

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22
Q

What is a peptidoglycan layer

A
  • a vital, lattice forming the bacterial cell wall, providing structural strength, maintaining cell shape
  • helps to identify Gram Pos from Gram Neg organisms
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23
Q

Describe what the peptidoglycan layer is made out of

A
  • NAG and NAM, chemical components that polymerize to form peptidoglycan
  • The cross link both vertically and horizontally
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24
Q

Describe the characteristics of Gram Pos organisms

A

– Thick peptidoglycan
layer
– No outer membrane

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25
Describe the Characteristics of Gram Neg Organisms
– Outer membrane – Thin peptidoglycan layer – Space between membranes is periplasmic space
26
What is the purpose of stains?
Stains are needed to allow us to see the organisms best using light microscopy
27
how are unstained organisms seen
can be seen using a “wet prep”- a suspension under a cover slip
28
Are organisms alive during the staining process
no, organisms are killed in the process
29
Describe a simple stain
-stain is applied and colours the organism e.x. methylene blue
30
What are complex stains and provide an example
A combination of stains applied in a sequence to stain different structures different colours
31
When was the gram stain developed and by who
Developed by Christian Gram in the 19th Century
32
What did Christian Gram discover
He found that a stain could be washed out of some organisms much more easily than others allowing differentiation of bacteria (Gram Pos and Gram Neg)
33
Describe the Method for Gram Stain
1. Before staining Gram Pos and Gram Neg are colourless 2. After Crystal violet stain (primary stain) both Gram Pos and Gram Neg are stained purple 3. Addition of Iodine: Iodine binds to the crystal violet and fixes it = acts as a mordant 4. Addition of Alcohol/Acetone: washes out the stain from gram negative bacteria only 5. Addition Safranin (counter-stain): stains the Gram Neg bacteria pink.
34
Why do some organisms not stain with the gram stain and what is the solution
Because of lipids in the cell walls giving it a waxy outer layer. In order to stain they must be stained by an acid fast method
35
What does the acid fast stain involve
1. staining organisms with a strong red stain (to “force” the stain into the cells of these organisms) 2. Washing out the stain with a mixture of acid and alcohol 3. Restaining (“counterstaining”) with a blue or green stain.
36
What allows the red stain in fast stain methods to stick?
The Red stain interacts and binds to the Mycolic acid (A long chain of lipids)
37
What are acid fast organisms also called
AFB (acid fast bacilli).
38
When restaining acid fast organisms what is the blue or green background composed of
other organisms that are not acid fast
39
What is the cell membrane composed of
- Lipid bilayer with proteins - enzymes involved in cell wall production, cellular metabolism, and production of some extra-cellular materials
40
what is the function of the cell wall
Controls the entrance and exit of substances from the cell
41
In the cell membrane of Gram Neg organisms what unique feature does it contain
Endotoxins
42
Describe the cytoplasm
– Liquid containing a variety of substances – Where metabolism occurs
43
What are ribosomes made of
Rna and Protein
44
what do ribosomes do
build proteins
45
is there 2 subunits of ribosomes
yes, Bacterial ribosomes are different from ribosomes in animal or plant cells (eukaryotic cells)
46
What are Bacterial chromosomes made of
A single long circular molecule of DNA
47
Are ribosomes a target for antibiotics
yes, since ribosomes are essential for bacteria life
48
Describe a key difference of bacterial chromosomes in animals/plants and bacteria
Not separated from cytoplasm (as in animal or plant cells which have nuclei)
49
What is a cell called when there is no nucleus
Bacteria are Prokaryotic
50
What are plasmids
Small, circular pieces of DNA
51
describe the three characteristics of plasmids
– Separate from the chromosome – Can be transferred between bacteria – May carry genes for antibiotic resistance
52
Describe Inclusions
– Granules in the cytoplasm – May act as storage of various substances
53
what are endospores
spores that are Environmentally tough and have a dormant form
54
where do endospores develop
in the cytoplasm of bacteria
55
describe 4 characteristics of endospores
– Do not grow or divide – Can remain viable for long periods – Only formed by certain genera of bacteria – Germinates to form a new cell
56
How are bacteria organized and classified and provide an example
Domains = Cells lacking nuclei (prokaryotes) vs cells with nuclei (eukaryotes) and kingdoms
57
describe the kingdoms
Animals * Plants * Fungi * Protista * Monera - the prokaryotic organisms
58
Describe what the classification is composed of and what aspect(s) are used most frequently in clinical practices
Kingdom Phylum Class Order Family  Used most Genus  frequently in Species  clinical practise
59
When do you use genus and species provide 2 examples
Genus and Species are used whenever we call a bacterium by its name (and they are initalics) EX. Homo sapiens (humans) Staphylococcus aureus
60
Describe how Staphylococcus aureus and provide an example
Staphylococcus aureus → S. aureus Keep capital letter of first word then add.
61
are Some bacteria are referred interchangeably with a common name if so provide an example
Yes, Streptococcus pyogenes = Group A Strep
62
Describe the Traditional classification of organisms
* Size, shape, gram reaction, need for O2 * Ability to metabolize sugars * Metabolic end products
63
What can traditional classification be supplemented by?
Comparison of 100-300 characteristics * Nucleic acid sequence of ribosomal RNA
64
Describe Aerobic organisms
(grows in air), obligate if must have O2.
65
describe Capnophilic organisms
needs CO2
66
describe Facultative anaerobe
grows in air, and can grow without oxygen
67
Describe Anaerobe organisms
grows without oxygen, and most species do not grow well in air as O2 is toxic for them
68
describe Microaerophilic organisms
grows in a low concentration of oxygen, but not in its absence or in air
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