Electron microscopy

Question 1

TEM resolution

Answer 1

50 picometres

Question 2

What can be viewed using TEM?

Answer 2

Shows structures with organelles, lipid membranes, viruses and macromolecules, such as DNA and proteins

Question 3

What sort of images are produced?

Answer 3

Black, white and grey

Question 4

How are these images produced?

Answer 4

Electrons are passed through specimen. Areas where the electrons pass are light. Regions where electrons are absorbed or reflected are darker- due to being more electron dense, such as proteins, compared to less electron dense cytoplasm

Question 5

What is cryofracture?

Answer 5

Techniques that allow TEM study of cells without fixation or embedding.

Question 6

What is cryofracture often used to study? + why

Answer 6

Lipid membranes. Fracture exposes the separate monolayers, revealing proteins

Question 7

Process of cryofracture

Answer 7

Small tissue specimens are rapidly frozen using liquid nitrogen.

Cut or fractured with a knife

Replica of the frozen exposed surface is produced in a vacuum by applying thin coats of vaporised platinum or other metal atoms.

After removal of organic material, replica can then be studied using TEM