問題一覧
1
Which dilution of a 1000mg/cm³ stock solution would give a 50mg/cm³ concentration?
B
2
How many E. coli cells were present in the original stock culture?
D. 8.0 x 10^8
3
Assuming each amino acid carries a single positive or negative charge, what is the protein's net charge at this pH?
A. - 4
4
Which row in the table describes properties of proteins that allow them to be seperated using the techniques shown?
A
5
Which of the following graphs represents the level of precipitate formed as the pH of a bovine insulin solution is changed?
C
6
Which amino acid was at its isoelectric point?
B. 2
7
SDS-PAGE seperates proteins by:
B. Size
8
From the diagram, the number of times that fragment T is longer than fragment S is
C. 4.0
9
An explanation for the seperation of different size fragments of DNA during SDS-PAGE electrophoresis is that
D
10
Which row in the following table shows the protein concentration (µg/ml) for the four samples?
C
11
The specific activity of the enzyme after purification stage 1:
27
12
The yield of enzyme after purification stage 3:
42
13
SDS polyacrylamide gel electrophoresis (SDS-PAGE) was used to estimate the number of proteins present after each step. Describe how SDS-PAGE is used to seperate proteins.
It denatures the proteins so that they have a uniform negative charge then separate them only by size
14
Which of the following shows the sequence of stages in the immunoassay?
C
15
Primary cell lines have
B
16
Trypan blue is used as a vital stain to identify viable cells when viewed in a haemocytometer. A vital stain
B. Only stains dead cells
17
The number of cells in the 10cm³ culture was
A. 2.75 x 10^7
18
Many species of bacteria can be grown in liquid culture. State the importance of aseptic technique when culturing micro-organisms.
Aseptic techniques prevent contamination by unwanted microbes
19
Calculate the number of cells per cm³ of the liquid culture.
1.2 x 10^5
20
State which of the antimicrobial compounds is more effective at killing bacterial cells and use the data to explain your choice
A because it killed a higher percentage of the total number of cells
21
What method, other than vital staining, can be used to determine the number of viable bacterial cells in a liquid culture?
Serial dilution - plate out on agar and count the colonies
22
Calculate the percentage of the protein which had been removed from the liquidised tissue by the end of stage 4
99.7%
23
Calculate:
7 times
24
Explain how separation by iso-electric point occurs
The iso-electric point is the pH at which a soluble protein has no net charge and will precipitate out of solution. If the solution is buffered to a specific pH, only the protein with an iso-electric point of that pH will precipitate
25
In affinity chromatography at Stage 4, a ligand specific to the enzyme being purified was bonded to agarose beads packed into a column. Describe how this method can improve the purity of the enzyme.
The enzyme binds to the ligand and are washed out for a pure sample
26
Scientists have reported that neurons produced in cell culture from human stem cells have the potential to function when grafted into the site of a spinal injury in rats. State why the cell culture medium in which the neurons were cultured should contain serum.
The serum can contain growth factors
27
Calculate the number of neurons in 1cm³ of the culture
110,000 cells
28
Suggest one disadvantage of cell counts performed using the haemocytometer
The numbers are an estimate
29
Bright field microscopy was used to view the cells grafted into the site of spinal injury. State another type of biological material that can be viewed using bright field microscopy.
Thin sections of tissue