Question 20N.3.HL.TZ0.13d
| Date | November 2020 | Marks available | [Maximum mark: 2] | Reference code | 20N.3.HL.TZ0.13d |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Describe | Question number | d | Adapted from | N/A |
Plant-derived proteins are likely to be safer for human use than those derived from mammalian cell cultures, as plant pathogens are not harmful to humans. The hepatitis B vaccine has been produced in tobacco plants.
In an experiment, soybean (Glycine max) cells were transformed using Agrobacterium tumefaciens to produce hepatitis B surface antigen (HBsAg). The amount of HBsAg made by the transformed soybean cells was measured at different times after transformation. The results are shown in the bar chart.
[Source: Reprinted by permission from Springer Nature from Plant Cell Reports.
Analysis of the limitations of hepatitis B surface antigen expression in soybean cell suspension cultures.
Ganapathi, T.R., Sunil Kumar, G.B., Srinivas, L., Revathi, C.J. and Bapat, V.A., © 2007. https://doi.org/10.1007/s00299-007-0379-7.]
Describe one bioinformatic method that could have been used to find the gene sequence for HBsAg.
[2]
a. gene databank; (e.g. GenBank/NCBI);
b. BLASTn to search similar DNA sequences;
c. ORF finder to search for the start codon;
Alternative:
d. protein database search for antigen (sequence);
e. example of database; (e.g. NCBI/SwissPro/Uniprot/PDB/other checked database);
f. BLASTp to search similar protein sequences;
Most answers didn't contain enough elements, although many mentioned BLASTn.
