21) Unit 1 - Liquid and Solutions & Separation Techniques

Question 1

List the apparatus that can be used to measure liquids

Answer 1

• measuring cylinder
• syringe
• auto pipette
• burette

Question 2

what is a serial dilution and why is it used?

Answer 2

•Repeated dilutions of a stock solution to reduce the concentration

Used?
•If trying to count bacteria in a sample but there are too many

Question 3

what is colorimetry

Answer 3

Finding the concentration of a pigmented solution using its absorbance

Question 4

how can colorimetry be carried out

Answer 4

• The absorbance of many known concentrations are collected
• A standard curve is made by plotting the results
• The absorbance of an unknown concentration is measured and compared to the curve to find its concentrations

Question 5

importance of buffers?

Answer 5

Biological processes are pH dependent and buffers help maintain the same pH

Question 6

Substances can be separated based on their…?

Answer 6

• Solubility
• Size
• Shape
• Charge

Question 7

Name 4 separation techniques

Answer 7

• Centrifugation
• Protein electrophoresis
• Protein Electrophoresis
• paper, thin layer and affinity chromotography

Question 8

Describe how centrifugation works?

Answer 8

• Centrifugation spins a sample at high speeds
• This allows the substance to be separated according to size and density
• The largest and densest material separates out first and is called the pellet (at the bottom)
• The remaining liquid is called the supernatant

Question 9

Describe how proteins are separted in protein electrophoresis works

Answer 9

• This uses a current flowing through a buffer to separate proteins
• The gel used in protein electrophoresis acts a sieve
• The migration through a gel depends on the proteins size and charge

Question 10

Describe what a iso-electric point is?

Answer 10

Iso-electric points occur when proteins are being separated using their pH.

It is the point in which the point in which the protein had a neutral charge and it will precipitate out of solution

Question 11

Describe how proteins are sepearted in paper and thin layer chromotography

Answer 11

• When proteins are separated based on their solubility

* separates a component using a solvent which draws up the different molecules, up the paper or TLC plate

Question 12

What does affinity chromatography rely on?

Answer 12

The binding interaction of a protein in the sample and a ligand

Question 13

Describe the process of affinity chromotography

Answer 13

• A complementary ligand/antibody to the desired protein is immobilized in a column
• The protein mixture is poured through the column
• Only the desired product will bind to the ligand/antibody
• The column is washed with a buffer of different pH that will decrease the ligands/antibodies affinity for the protein
• The desired product can be recovered