Cell Basics and Microscopy (Lecture 3) Flashcards

(47 cards)

1
Q

What is cell growth the result of?

A

activities of metabolism

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2
Q

What do cells use the metabolic process for?

A
  1. gain mass
  2. replicate their DNA
  3. divide
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3
Q

You have discovered a new ovoid (oval-shaped) microorganism with a nucleus, and genome containing multiple linear chromosomes. The new microorganism is…

A

most likely a eukaryote

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4
Q

Resolution

A

the smallest distance by which two objects can be separated and still be distinguished

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5
Q

What depends on the resolution of the observer’s eye?

A

the size at which objects become visible

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6
Q

Light microscopy has a resolution limit of __________.

A

200nm

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7
Q

What does electron microscopy require ____________________ conditions that can damage or alter cell structures.

A

fixation/freezing

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8
Q

What is the limitation of the naked eye?

A

resolution is limited to 150 micrometer

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9
Q

What is used to observe most microorganisms?

A

light microscopy

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10
Q

What three lenses does light microscopy usually have?

A

low-power, high-power, and oil-immersion

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11
Q

Bright-field

A

light passing through the cell directly forms the image

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12
Q

Phase-contrast and differential-interference-contrast

A

exploits the phase change of light passing through an object varying thickness and density to produce an image

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13
Q

Dark field

A

illuminating rays are directed from the side so only scattered light enters the microscope lens

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14
Q

When is light microscopy useful for?

A

examining cell when they are alive

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15
Q

Phase-contrast, differential-interference-contrast, and dark field are all useful for looking at cells while they ____________________.

A
  1. move around
  2. mitosis/cell migration
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16
Q

What does staining provide?

A

contrast

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17
Q

What does a simple stain technique involve?

A

flooding a prepared specimen with basic dye

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18
Q

Negative stain technique uses _________ dye.

A

acidic

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19
Q

What does acidic dye repel?

A

cell walls leaving clear cells on a dark background

20
Q

Fluorescence microscopy

A

relies on the use of fluorescent chemicals for visualization

21
Q

Fluorescent chemicals absorbs light at one _______________ and emits light at a ______________ longer wavelength.

A
  1. wavelength
  2. specific
22
Q

In Fluorescence microscopy what is the specimen stained with?

A

fluorescent chemical

23
Q

What excites fluorescent chemicals?

A

light from a mercury lamp

24
Q

How does Fluorescence microscopy work?

A

chemical emits a specific wavelength of light the light from the sample is passed through a filter so only the emission wavelength from the fluorescent chemical is detected

25
What are some uses of Fluorescence microscopy?
-view a specific cell in a mixture of different cells -view specific cell component in a cell
26
Transmission electron microscopy (TEM)
electrons pass through specimen and it reveals internal structures
27
Scanning electron microscopy (SEM)
electrons scan the specimen surface and reveals external features in 3D
28
What does both SEM and TEM require?
staining with heavy metals this preparation will kill the cell
29
Morphology
cell shape
30
Major cell morphologies
1. coccus 2. rod
31
Cells with unusual shapes are...
1. spirillum (spiral) 2. spirochetes (corkscrew) 3. appendages bacteria 4. filamentous bacteria
32
What are some selective forces that are involved in creating the morphology?
1. optimization for nutrient uptake 2. swimming motility in viscous environments 3. gliding motility
33
Cocci shape
spherically shaped bacteria
34
Where may cocci bacteria grow in?
1. chains 2. clusters 3. tetrads 4. sarcinae
35
Chains
Strepto-
36
Clusters
staph-
37
Bacilli shape
rod-shaped bacteria
38
How can bacilli grow?
1. arrange in pairs 2. chains 3. just short and rounded
39
Bent rods
vibrios
40
Corkscrew
spirilla with rigid cell wall and external flagella
41
Spirochetes are corkscrew-shaped bacteria but are different from spirilla because...
-flexible cell walls -internal flagella
42
Most cultured rod-shaped bacteria are between ________ and ___________ micrometers in width.
0.5 and 5.0
43
Size range for eukaryotic cells
10 to >200 micrometers in diameter
44
Size range for prokaryotes
0.2 to >700 micrometers in diameter
45
Describe smaller cells surface area compared to their cell volume
they have more surface area than their cell volume
46
What does having a larger surface area allow?
1. support greater nutrient exchange per unit cell volume 2. tend to grow faster than larger cells
47
Who's bigger eukaryotes or prokaryotes?
eukaryotes