Électrophorèse (Biochimie) Flashcards Preview

Biochimie > Électrophorèse (Biochimie) > Flashcards

Flashcards in Électrophorèse (Biochimie) Deck (52)
Loading flashcards...
1

2

Qu'est ce qui se passe aux protéines lorsqu'il y a une infection:

L'albumine diminue due à un cataabolisme accentuée mais les globulines sont augmentés en raaison de la synthèse d'anticorps contre l'agent infectieux.

 

3

Quel est l'utilité de l'électrophorèse:

Sépare et quantifie les différentes protéines sériques.

 

4

Quels sont les substances électrophorésées:

Protéines, lipides, hémoglobiunes et iso enzymes

 

5

Électrophorèse:

Technique de séparation non gravimétrique

 

6

Tout système électrophorétique doit contenir 3 ingrédients essentiels:

  1. un champ électrique
  2. des particules chargées
  3. un milieu conducteur dans lequel le mouvement se produit

 

7

Iontophorèse:

La migration des petits ions

 

8

Plusieurs facteurs peuvent affecter la vitesse de migration des ions:

  1. support
  2. voltage
  3. dimensions de la molécule
  4. pH du tampon (FI)
  5. charge de la molécule
  6. la température

9

Pourquoi utilise-on des protéines chargées négativement:

Car les protéines chargées positivement exhibent plus d'adsorption (sur le support) que ceux chargées négativement.

 

10

Électrophorèse libre:

le milieu est liquide avec le tampon à un tel pH

 

11

Électrophorèse de zone:

Le milieu est un support trempé dans un tampon à un tel pH.

 

12

Quels sont les différents types de support:

  • papier
  • acétate de cellulose (5 zones)
  • gels d'agar
  • gel d'acrylamide (plus que 20 zones)
  • gel d'amidon
  • gel d'agarose (12 zones)

13

Lors d'une électrophorèse de protéine de routin, qu'est ce qui peut faire que la migration des protéines semble plus rapide que d'habitude:

  1. executer la procédure à une température plus basse
  2. utiliser un tampon ayant un pH plus élevée
  3. utiliser un tampon ayant une plus grande FI
  4. ajuster le courant à un niveau plus bas

 

2 - utiliser un tampon ayant un pH plus élevée

14

Quelle circonstance entrainera le regroupement des bandes de protéines tout près du point d'application lors d'une électrophorèse:

  1. un tampon avec un pH neutre
  2. un tampon avec une faible force ionique
  3. un voltage trop élevé
  4. un temps d'électrophorèse prolongé

 

1 - un tampon avec un pH neutre

15

Qu'est ce qui se passe lorsque la force isoélectrique augmente:

Le nuage ionique est plus fort, la mobilité diminue et la résolution augmente.

 

16

Qu'est ce qui se passe lorsque la force ionique diminue:

Le nuage ionique diminue, la mobilité augmente et la résolution diminue.

 

17

Quel est la meilleure force ionique:

Entre 0.01-0.1 M

 

18

Cercle vicieux:

Quand le temps augmente, le courant augmente, la température augmente et la force ionique augmente.

 

19

An increase in which of the following would increase the movement of particles through a solution in electrophoresis:

  1. voltage applied to the electrophoretic system
  2. viscosity of the solvant
  3. size and symmetry of the particles
  4. all of the above

 

1 - voltage applied to the electrophoretic system

 

20

Which of the following proteins will show the greaatest net negative charge in a pH 8.6 buffer:

  1. protein A with an isoelectric point of 7.5
  2. protein B with an isoelectric point of 8.0
  3. protein C with an isoelectric point of 8.6
  4. protein D with an isoelectric point of 9.6

 

1 - protein A with an isoelectric point of 7.5

21

An increase in the ionic strength of the electrophoretic buffer while operating at constant current will cause the voltage to _______, the electrophoretic migration of macromolecules to _________, and the separation of macromolecules to __________.

  1. increase, increase, increase
  2. increase, increase, decrease
  3. decrease, decrease, increase
  4. decrease, decrease, decrease

4 - decrease, decrease, decrease

22

If the ionic strength of the electrophoretic buffer is increased from 0.1M to 1.0M and the system is operated at the same fixed voltage when using each buffer concentration, which of the following describes the results that would likely be seen when using the 1.0M buffer, as compared to the results seen with the 0.1M buffer:

  1. electrophoresis separation would be achieved in shorter time with the 1.0M buffer, with greater resolution
  2. the electrophoresis pattern would be distorted, and the macromolecules may be denatured when using the 1.0M buffer
  3. electrophoretic separation would be achieved in a shorter time with the 1.0M buffer, with decreased resolution
  4. the electrohporetic separation time would have to be increased 10 fold to account for the 10 fold increase in buffer concentration

 

2 - the electrophoresis pattern would be distorted, and the macromolecules may be denatured when using the 1.0M buffer

23

The net charge of a macromolecule is determined by the total number of charged groups withihn the macromolecule. The charge associated with the zeta potential of a macromolecule in an electrohporetic environment compares in which of the following ways to the net charge on the macromolecule itself:

  1. the zeta potential is greater than the net charge
  2. the zeta potential is less than the net charge
  3. the zeta potential is equal to the net charge
  4. the zeta potential has no relationship to the net charge

 

2 - the zeta potential is less than the net charge

24

When considering the factors that influence the mobility of macromolecules, the relaxation effect would tend to __________ electrohporetic mobility, because there is a momentary _________.

  1. lower, formation of a double layer of charge about the macromolecule
  2. increase, neutralization of charge around the macromolecule
  3. lower, electrical field that acts in the opposite direction to the applied field
  4. increase, enhanced electrical field that acts in the same direction aas the applied field

 

3 - lower, electrical field that acts in the opposite direction to the applied field

25

Electro-osmosis is the migration of supporting medium counterions and solvent toward the appropriate electrode. This net flow of counterions and solvent is in the opposite direction tot he migration of the macromolecules of interest. Which of the following statements best describes the effect of electro-osmosis:

  1. electro-osmosis will only affect the final positions of the macromolecules but not their separation
  2. electro-osmosis will prevent macromolecule separation from occuring
  3. electro-osmosis is the mechanism by which electrophoretic separation of macromelcules occurs
  4. electro-osmosis only occurs in capillary electrophoresis and is the mechanism of separation in the relatively new technique

 

1 - electro-osmosis will only affect the final positions of the macromolecules but not their separation

26

The discontinous solvent system used to enhance electrophoretic resolution in which movement comes to a stop because of a lack of net charge is:

  1. isotachophoresis
  2. disk electrophoresis
  3. isoelectric focusing
  4. gel electrophoresis

 

3 - isoelectric focusing

27

Is the following statement true or falsa and why. A thinner electrophoretic support is associated with a greater sensitivity:

  1. true because a thinner support will require less sample to produce a detectaable spot
  2. true because a thinner support will allow more exposure to air
  3. false because a thinner support can hold less sample
  4. false because a thinner support can hold more solvent and effectively dilute the sample

 

1 - true because a thinner support will require less sample to produce a detectaable spot

28

It is known that pH influences the charge of an analyte and, if set appropriately, can enhance electrophoretic mobility. In an attempt to improve separation of serum proteins, the analyst set the pH of the buffer at an extremely basic level. Following electrophoresis, it was determined that the desired results were not achieved. Which of the following explains why the modification was not successful:

  1. at the very basic pH, the proteins may have been denatured
  2. at the very baasic pH, the proteins may have been dissociated
  3. at the very basic pH, the fraction of current carried by buffer hydroxyl ions resulted in poorer separation
  4. all of the above are possible explanations

 

4 - all of the above

 

 

29

Which support medium is most used in immunoelectrophoresis:

  1. polyacrylamide gel
  2. agarose
  3. agar
  4. starch gel

 

2 - agarose

 

30

One of the advantage of capillary electrophoresis over other types of electrophoresis is the potential to separate uncharged analytes. The separation of uncharged analytes is made possible in this technique by:

  1. the very short migration distance, which allows diffused uncharged analytes to be isolated along with charged analytes
  2. the lack of electro-osmosis, allowing the migration of uncharged analytes
  3. the use of micelles
  4. the use of more powerful methods of detection

 

3 - the use of micelles