Quiz 3

Question 1

isoelectric point (pI) =

Answer 1

the pH at which a particular molecule carries no net electrical charge or is electrically neutral

Question 2

At a pH below their pI, proteins carry…

At a pH above their pI, proteins carry…

Answer 2

…a net positive charge

…a net negative charge.

Question 3

• @ its pI, proteins are at their…

- Therefore, by changing the pH of the solution to the pI, the…

Answer 3

…lowest solubility (due to net 0 charge)

…solubility of the protein will be lowered

Question 4

Bradford Assay is based on…

When the dye binds to the protein…

The amount of light absorbance at a wavelength of 595 nm is directly proportional to…

Answer 4

• the simple binding affinity for a particular dye (Bio Rad Protein Assay Dye) to protein.
• it changes from red to blue.
• the amount of protein

Question 5

Histochemistry =

Answer 5

= the utilization of various stains and chemical staining procedures to visualize where specific cellular components are located in tissue sections (or thin layers of cells)

Question 6

The basic steps in histotechnique: (4)

Answer 6

1. ) The tissue or organ is removed from the organism and preserved = FIXATION
2. ) The fixed tissue is sectioned (thinly sliced) using a microtome = SECTIONING
3. ) The sectioned tissue is placed on a microscope slide and stained = STAINING
4. ) The stained tissue sections are then permanently mounted = MOUNTING

Question 7

Difference between native and non-native gel electrophoresis:

Answer 7

Native electrophoresis the proteins are held in their normal (Native) form
whereas with non–native electrophoresis the proteins are denatured (i.e., their normal 3-D structure is disturbed).

Question 8

What role does the Nonidet P–40 serve in the extraction buffer?

Answer 8

Nonidet P-40 was used specifically for solubilising membrane proteins during an isolation of a membrane-protein complex. The role it served in this lab was to isolate the proteins from the membrane to solely receive a protein substance.