Quiz Block 2 Flashcards

1
Q

Mention an agent that is commonly used for precipitation of succinct acid?

A

Calcium hydroxide (CaOH)
Ammonium sulphate (NH4SO4)

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2
Q

True or False: In the context of precipitation, the flocculation step is enhanced when electrostatic repulsion is minimised?

A

True - If repulsion is minimized, the particles aggregate

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3
Q

Can you give one example of a compound that is used in the process of “salting out” in protein precipitation

A

Ammonium sulphate (NH4SO4) is the most common

It is also possible to use phosphate salts

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4
Q

Liquid-liquid extraction processes are normally more efficient when the extractors are set in concurrent/countercurrent fashion. Aqueous two-phase extraction systems are/are not particularly recommended for protein extraction

A

Countercurrent - Allows for higher driving force

Are recommended for protein extraction

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5
Q

What is the driving force in electrodialysis?

A

Electric potential difference

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6
Q

Separate the terms dealing with electrodialysis vs liquid-liquid extraction: Water splitting – Partition coefficient – Bipolarity – Two phase extraction – Agitated columns – Catode

A

Electrodialysis: Bipolarity, Catode, Water splitting

Liquid-liquid extraction: Partition coefficient, two-phase extraction, agitated extraction columns

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7
Q

Why is chromatography not recommended for purification of succinct acid

A

Selectivity is limited and the yield is low
Chromatography is very expensive

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8
Q

Which cells are generally considered the easiest to disrupt?

A

Mammalian cells are easier to disrupt
Plant cells are harder to disrupt due to rigid and strong cell wall

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9
Q

What is often a big issue after cell disruption that has to be solved by dilution?

A

High viscosity

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10
Q

What gives the cell wall of Gram-positive bacteria its mechanical support?

A

Compound cell wall made of peptidoglycan

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11
Q

What physiological property of Gram-negative bacterial cell walls has to ve considered when planning their disruption?

A

The cell wall has an outer lipopolysaccharide membrane

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12
Q

Over-expression of recombinant protein products in bacteria often leads to the formation of x

A

Inclusion bodies

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13
Q

Which enzyme can be used to break down bacterial cell walls?

A

Lysozyme

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14
Q

What causes cells to break during high pressure homogenization?

A

Shear stress

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15
Q
  1. Using a high pressure homogenizer you obtain 53% release of protein in one pass, when disrupting E.coli. How many passes do you need to ensure 90% release? Use ln(Rm/(Rm-R)=K*N
A

No. of passes 1
Protein release (R) = 0.53 (68%)
Required release = 0.90 (90%)

Substitite the date into the equation:
ln(1/(1-0.53)=K*1, solve for K
K=0.755

Substitute K into the equation with the required release:
ln(Rm/(Rm-R)=KN
ln(1/(1-0.90))=0.755*N, solve for N
N = 3.049

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16
Q

What are the two methods used to aggregate biological particles and cells?

A

Charge neutralisation (using aluminium salts)
Binding particles via bridging using poly-ionic polymers or metallic salts

17
Q

Which two major forces act on colloid particles?

A

Electrostatic repulsion
van der Waals forces

18
Q

Hwo do poly-ionic polymers aggregate bio-particles

A

Adsorbing on to adjacent particles and forming bridges which causes aggregation

19
Q

What is the most used equipment for solid-liquid extraction?

A

Soxhlet extractor

20
Q

How do you often cause precipitation after a solid-liquid extraction step?

A

Natural precipitation over time (sedimentation) or addition of an antisolvent

21
Q

What are two of the benefits when using Deep eutectic solvents compared to traditional organic solvents?

A

They are more environmentally friendly (allows for recycling of solvent)
Easier unit operation integration
Reduction of energy and solvent consumption during extraction
Non-toxic