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Microbiology > Structures, Staining, And Taxonomy > Flashcards

Structures, Staining, And Taxonomy Flashcards

1
Q

What are appendages

A

Things that are attached to the outside of the cell

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2
Q

What are the types of appendages

A

Flagella, fimbriae, pili

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3
Q

What is the surface and cell wall layers in a bacteria from the outside in

A

Capsule
Cell wall
Cell membrane

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4
Q

What is in the cytoplasm in a bacteria

A

Chromosomes, plasmids, ribosomes, inclusions

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5
Q

What do flagella look like

A

Long slender, whip like structures, made of protein

Can be single (monotrichous) or multiple in tufts around the cell (peritichous)

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6
Q

What is the purpose of flagella

A

Enable bacteria to move by roasting like a propeller

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7
Q

How is flagella observed

A

Can’t be seen with gram stain, only with special stains or electron microscopy

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8
Q

What do fimbriae look like

A

Shorter, thinner filaments made of protein

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9
Q

What is the purpose of fimbriae

A

Enable bacteria to attach to substances

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10
Q

What do pili look like

A

Similar to fimbriae in structure

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11
Q

What is the purpose of Phili

A

Involve them in the transfer of DNA between bacteria

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12
Q

What is a capsule

A

Material that is secreted by bacteria and covers the exterior of the cell

Often made of polysaccharide/sugar, may be a thick layer; slime coating

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13
Q

What does a bacterial cell wall look like

A

Differs from animal cells or fungi

It is a strong layer made of peptidoglycan

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14
Q

What is the purpose of a cell wall in bacterial cells

A

It maintains cell shape and integrity

It is the principal target for antibiotic action

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15
Q

How are cell walls in bacterial cells viewed

A

Using gram stains

Differs between gram pos and neg

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16
Q

Why is the bacterial capsule considered a virulence factor

A

The bacterial capsule is also considered a virulence factor as it enhances the ability of bacteria to cause disease by preventing phagocytosis.

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17
Q

What is the peptidoglycan layer composed of

A

NAG and NAM (sugars) that are cross linked with amino acids (proteins) that make a long network the covers the cell and protects it from the environment

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18
Q

Composition of gram positive

A

Thick peptidoglycan layer

No outer membrane

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19
Q

Composition of gram negative

A

Outer membrane
Then peptidoglycan layer
Space between membranes is the periplasmic space

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20
Q

Is there a nucleus in a bacterial cell

A

No, there is no nucleus in a prokaryotic cell

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21
Q

What are acid fast bacteria

A

They have extra waxy lipids in the outside layer that prevent it from being stained using gram staining

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22
Q

What is wet prep

A

It is used for unstained organisms to be seen

A wet prep is suspended under a cover slip

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23
Q

What are simple stains

A

Stain is applied and colours the organism
E.g. methylene blue

Does differentiate organisms from one another just its shape, can’t tell if its gram pos or neg because there is no difference in colour

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24
Q

What are complex stains

A

Stains may be combined to stain different structures different colours

E.g., Gram staining: staining that is applied in sequence with a step to remove stain in between

25
What is giemsa stain
It is a type of complex stain It is used to stain malaria parasites Stains the nucleus red and the cytoplasm blue
26
How developed gram stains and when
Christian gram in the 19th century
27
How did Christian Gram discover Gram Staining
He found that a stain could be washed out of some organisms much more easily than others, the technique allows differentiation of many bacteria into 2 groups (gram positive and gram negative) corresponding to cell wall type
28
What type of gram stain does not retain the stain
Gram negative, stays pink
29
What is the method for gram staining
1. Crystal violet: stains all the bacteria dark purple (primary stain) 2. Iodine: binds to crystal violet and fixes it (acts as a mordant) 3. Alcohol/Acetone: washes out the stain from gram negative bacteria* Gram originally stopped here, and said that the organisms that stained purple were positive because they could be seen and gram negative remained colourless (decolourizer) 4. Sacranin: stains the gram negative bacteria pink (counter stain) - This step was added layer, so both the gram neg and pos could be viewed
30
When is acid fast staining used
When bacteria cannot be stained by the Gram stain because of lipids in the cell walls E.g., Mycobacterium tuberculosis: the tuberculosis bacterium
31
How does acid fast staining stain
1. Staining with a strong red stain to force the stain into the cell 2. Washing out the stain with a mixture of acid and alcohol 3. Restating with a blue or green stain (counterstaining) Acid fast organisms are red Other organisms are the colour of the counter stain (blue or green)
32
What is the cell membrane of a bacterial cell composed of
Lipid bilayer with proteins It also contains enzymes involved in the cell wall production, cellular metabolism, and the production of some extra-cellular materials
33
What is different about the cell walls in gram negatives
It contains endotoxin, which is a polysaccharide (LPS)
34
What is the purpose of the cell wall in bacterial cells
Controls the entrance and exit of substances form the cell
35
What is the purpose of a cytoplasm in a bacterial cell
It is where metabolism occurs
36
What is the composition of a bacterial cytoplasm
Liquid counting a variety of substances
37
What is the purpose of ribosomes in a bacterial cell
They are the structures where proteins are made
38
What do ribosomes look like in prokaryotes
Have two subunits Made of RNA and protein
39
What does a bacterial chromosome look like and what is it composed of
A single long circular molecular of DNA composed of DNA
40
What do plasmids look like
Small, circular pieces of DNA
41
What happens if plasmids integrate into the chromosome
it becomes part of that organism and if it has a gene with antibiotic resistances than the organism will retain this and will continue to be present when replicated
42
What is the purpose of plasmids
Can be transferred between bacteria, may carry genes for antibiotic resistance
43
What are inclusions and what is their purpose
Granules in the cytoplasm, act as storage of various substances
44
What are endospores (“spore”)
They develop in the cytoplasm of bacteria, they do not grow or divide, they are environmentally tough and remain in dormant form so they can be viable for long periods Only in some bacteria
45
How do spores work
When the environment becomes favourable then the organism can germinate out of this spore and germinate gain
46
What is a Domain
Prokaryotics vs, Eukaryotics
47
What are Kingdoms
Animals Plants Fungi Protista Monera (prokaryotic organisms)
48
What type of classification is used when we call a bacteria by its name
The capital letter —> Staphylococcus = Genus The lower case letter —> aureus = species Family is Staphylococcaceae
49
What are the two ways bacteria is classified
Traditional: don’t need any special equipment Supplemented: Modern tool, sequencing their chromosomes or ribosomes, used when dealing with organisms we can’t grow or because they are dead
50
What are the traditional ways to classify bacteria
Size, shape, gram reaction, need for O2 Ability to metabolize sugars Metabolic end products
51
What is an aerobic bacteria
Grows in air Obligate if it must have O2 Capnophilic if it needs CO2
52
What is a Facultative anaerobe
Grows in air and can grow without oxygen
53
What is an anaerobe
Grows without oxygen, and most species do not grow well in air as O2 is toxic for them
54
What is a microaerophilic
Grows in a low concentration of oxygen, but not in its absence or in air
55
Which structure enables bacteria to be motile (move)
Flagella
56
What substance found in the bacterial cell wall gives it strength and its integrity is important for bacterial survival
Peptidoglycan
57
The gram stain is useful because
It differentiates bacteria based on their cell wall structure
58
Which is the correct order of use of regents for the gram stain
Crystal violet, iodine, decolourizer, safranin
59
For an organism called Staphylococcus aureus the Staphylococcus refers to the
Genus

Microbiology (7 decks)

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