ch 8, 9

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Which term best describes protein crystals?

Amorphous

Irregular

Random

Regular (correct)

What are protein crystals made of?

Identical molecules or molecular complexes (correct)

Random mixtures

Different molecules

Various compounds

What is the structure of protein crystals?

Amorphous

Irregular

Regular (correct)

Random

Which of the following can act as a nucleus in the nucleation process?

A dust particle Signup and view all the answers

What happens if the supersaturation is too high in a solution?

An overabundance of tiny crystals form Signup and view all the answers

When does crystal growth often occur in supersaturated solutions?

Only in the presence of added nuclei or seeds Signup and view all the answers

Which of the following can cause cessation of growth in crystal formation?

Development of growth defects Signup and view all the answers

What is mother liquor in the context of crystal formation?

The solution in which the crystal exists Signup and view all the answers

How is mother liquor different from the original crystallization screening solution?

It has a higher concentration of solute Signup and view all the answers

What is the role of temperature in crystallization?

It determines the size of protein crystals Signup and view all the answers

Which method is commonly used by crystallographers to obtain protein?

E. Coli expression systems Signup and view all the answers

What can cause low expression yields in E. Coli expression systems?

Unstable plasmid or mRNA Signup and view all the answers

What is a major issue with protein concentration?

Consistency and reproducibility Signup and view all the answers

Which temperature is considered ideal for keeping an individual crystal screen constant?

4° C Signup and view all the answers

At which temperatures should each set of conditions be screened during crystal formation?

4° C and room temperature Signup and view all the answers

Which temperature should be tried during crystal screening, in addition to 4° C and room temperature?

12° C Signup and view all the answers

Which type of interactions are more important than hydrophobic interactions in crystal packing?

Electrostatic interactions Signup and view all the answers

What does crystal packing refer to?

The arrangement of molecules within a crystal Signup and view all the answers

What is the main issue when it comes to reproducibility in crystal packing?

Buffer composition Signup and view all the answers

Which temperature is commonly used for X-ray diffraction measurements of protein crystals?

Cryogenic temperatures Signup and view all the answers

What is the purpose of adding cryoprotectants to protein crystals?

To stabilize the crystal structure Signup and view all the answers

What effect does cryoprotectant addition have on the nucleation temperature of water?

Decreases the nucleation temperature Signup and view all the answers

Why can't we see proteins with light microscopes?

Proteins are too small to be resolved by the wavelength of visible light Signup and view all the answers

What is the wavelength range of visible light?

400 - 700 nm Signup and view all the answers

What is the wavelength of X-rays?

1 angstrom (0.1 nm) Signup and view all the answers

Which type of device is used to force electrons to follow a closed 'ring' trajectory?

Bending magnets Signup and view all the answers

What is the main difference between a wiggler and an undulator?

Wigglers emit radiation as a series of sharp peaks at prescribed wavelengths Signup and view all the answers

What is the purpose of insertion devices in synchrotron radiation facilities?

To produce higher intensity, shorter wavelength x-rays Signup and view all the answers