2.1 - Cell Structure Flashcards

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1
Q

Define MAGNIFICATION.

A

How much bigger an image appears compared with the original object.

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2
Q

Define RESOLUTION.

A

The ability of an optical instrument to see or produce an image that shows fine detail clearly - distinguishing two objects as separate from each other.

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3
Q

Give 4 benefits of OPTICAL MICROSCOPES.

A
  1. Relatively cheap
  2. Easy to use
  3. Portable and able to used in the field as well as in laboratories
  4. Able to be used to study whole LIVING specimens.
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4
Q

What’s the common max magnification of optical microscopes?

A

x1500 (some x2000)

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5
Q

What’s the resolution of optical microscopes?

A

200 nm

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6
Q

What is the formula for calculating TOTAL magnification?

A

total magnification = magnifying power of the OBJECTIVE lens x magnifying power of the EYEPIECE lens

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7
Q

What is a photomicrograph?

A

A photograph of the image seen using an optical microscope.

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8
Q

How do laser scanning microscopes work?

A

They use laser light to scan an object point by point and assemble, by computer, the pixel information into one image, displayed on a computer screen.

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9
Q

Give 4 uses/benefits of laser scanning microscopes.

A
  1. Images are high resolution and show high contrast.
  2. The microscopes have depth selectivity and can focus on structures at different depths within a specimen, so can be used to clearly observe whole living specimens, as well as cells.
  3. They are used in the medical profession in order to give a swift diagnosis and earlier, more effective treatment.
  4. Used in many branches of biological research.
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10
Q

What is the resolution of electron microscopes?

A

0.004 nm

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11
Q

How do electron microscopes work?

A

The electrons are fired from a cathode and focused, by magnets, on to a screen or photographic plate.

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12
Q

How do Transmission Electron Microscopes (TEM) work?

A
  1. The specimen has to be chemically fixed by being dehydrated and stained.
  2. The beam of electrons passes through the specimen,
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