April 2

Question 1

What is the problem with 3D reconstruction for cryo-EM

Answer 1

It is that Cryo-EM gives 2D images, particles should hopefully be at random orientations

Question 2

What is the projection slice theorem, how it help us with 3D reconstruction problem?

Answer 2

It is that each 2D image can be used to get 2D fourier transform, then combining these fourier transforms makes 3D fourier transform, then converted to real space

Question 3

We can computationally separate conformational states or species as ________.(Cryo-EM)

Answer 3

Classes. you have class 1,2 etc that may be open channel, then calcium bound etc

Question 4

What is Fourier Shell correlation? What used for in Cryo-EM?

Answer 4

It is method to measure similarity between two 3D volumes over different spacial frequencies.
It is used to estimate resolution of 3D reconstructions by dividing dataset into 2 random halves, then make 2 3D volumes. These two are compared