2015 Exam

Question 1

Differences and Similarities between LM and EM: Resolution (2)

Answer 1

• Both modalities are dependent on waves but LM uses a longer wavelgnth and has a lower resolution
• Abbe’s Law, d = lambda/2*NA

Question 2

Differences and Similarities between LM and EM: Visualisation of Markers and Other Objects (2)

Answer 2

• LM is based on fluorophors and will only show labelled proteins
• Markers for EM have to be electron dense (gold particles or quantum dots) but through staining there is “reference space” as additional info in EM

Question 3

Differences and Similarities between LM and EM: Imaging Conditions (2)

Answer 3

• LM can work in ambient conditions therefore allows live imaging
• EM only works in a vacuum therefore only fixed material can be imaged

Question 4

How can limitations of EM and LM be prevented? (2)

Answer 4

• Combining LM and EM in CLEM (Correlative Light Electron Microscopy) framework, advantages of both techniques.
• Reduces the changes of changes in the sample during the process of data collection

Question 5

What can be said about the image f(x,y)? (2)

Answer 5

• f(x,y) will be a dark image since the intensities are concentrated in the lower half of the intensities range
• Will consist of only 3 intensity vaues w/ equal probabilities, p=1/3

Question 6

Intensity transformation that will improve the contrast of the image when it is used to modify it’s intensity

Answer 6

Histogram Equalisation