479880
Description
Flashcards by sophietevans, updated more than 1 year ago
|
Created by sophietevans
almost 11 years ago
|
|
| Question | Answer |
| What does SDS stand for? What is its purpose in this technique? | Sodium dodecyl sulphate - this is a detergent which 'uncurls' proteins and coats them in a uniform negative charge, meaning that the only factor determining the distance travelled through the acrylamide gel is its size. |
| What is the point of the molecular weight markers? | These are known proteins (of known molecular weight) so a standard curve of molecular weight plotted against distance travelled in the gel can be constructed in order to work out the molecular weight of unknown samples. |
| What is the difference between the stacking gel and the resolving gel? What is its significance? | The stacking gel has a lower concentration of acrylamide, which means it forms larger pores when it cross-links with TEMED, so all the proteins in a given sample can travel through to the resolving gel. The resolving gel has a higher concentration of acrylamide to cross-link with TEMED, producing smaller pores which separate the proteins based on size throughout the gel. This allows the proteins to be separated. |
| What is the function of glycerol mixed in with the samples in the stacking gel? | It is a viscous substance which weighs down samples when they are added to the sample wells. This prevents the samples from diffusing into the gel before the gel is run. |
| What is the function of the bromophenol blue dye added with the samples? | This allows the progress of electrophoresis to be tracked. The dye molecules are smaller than any of the proteins and so they travel the fastest/furthest, allowing the movement of the proteins to be estimated/visualised. |
| Towards which electrode do the proteins travel? Why? | They travel towards the positively charged anode because they are negatively charged. |
| Once the plate has been run, the bromophenol blue dye will have separated from the proteins. How are they visualised once again? | Coomassie blue dye is applied to the plate. The plate is then de-stained, which means the remaining dye only stains the protein bands, allowing them to be accurately visualised. |
| What is the general process called when SDS-PAGE is combined with an ELISA in order to produce a 'print' of the electrophoresis gel? | Western blotting. |
| When immunoglobulin samples are run on an electrophoresis plate, why are two protein bands produced? | Because the proteins are separated into the light chains (which travel furthest) and the heavy chains. |
| What is a thick protein band indicative of? | A lot of protein. |
| How many heavy, and how many light, chains does a pentameric immunoglobulin (IgM) have? | 10 of each. |
| How many heavy, and how many light, chains does a dimeric immunoglobulin (e.g. IgA) have? | 4 of each |
| How many heavy, and how many light, chains does a monomeric immunoglobulin (e.g. IgG) have? | 2 of each |
Want to create your own Flashcards for free with GoConqr? Learn more.