Analysis of cell components

The difference between magnification and resolution is what?

Resolution - How detailed an image is: The minimum distance apart that two objects can be distinguished as separate objects.(Resolution is limited by wavelength of radiation uses e.g. light.)

Magnification – how much bigger the image of a sample is compared to its real (actual) size.

Light microscope

- Use light to form a 2D image

- Visible light longer wavelength so lower resolution 200nm

- Low magnification x1500

Light microscope - pros and cons

Cons:

- 2D image

-Only used on thin specimens

-Low resolution; can’t see internal structures of organelles or organelles smaller than 200nm e.g. ribosomes

-Low magnification

Pros:

-Can see living organisms

Scanning electron microscope

Use electrons to form a 2D image

- Beams of electrons scan surface, knocking off electrons from the specimen, which are gathered in a cathode ray tube to form an image.

- Electrons shorter wavelength(so higher resolution 0.2nm)

- High magnification - x1500000

Scanning electron microscope - pros and cons

Cons:

-Vacuum; can’t see living organisms

-Lower resolution than TEM

Pros:

-3D image

-High resolution; can see internal structures of organelles

-High magnification

-Used on thick specimens

Transmission electron microscope

Use electrons to form a 3D image

- Electromagnets focus beam of electrons onto specimen, transmitted, more dense = more absorbed = darker appearance

- Electrons shorter wavelength (so higher resolution 0.2nm)

-High magnification x1500000

Transmission electron microscope - pros and cons

Cons:

-2D image

-Only used on thin specimens

-Vacuum; can’t see living organisms

Pros:

-High resolution; see internal structures of organelles

-High magnification