Explain how infection by a pathogen can be detected by the presence of its genetic material and of its proteins.

Presence of genetic material (PCR and/or microarray): [Allow 4 max]

PCR:
a. presence of the genetic material can be amplified by PCR;

b. if the genetic material is RNA, a reverse transcription PCR must be performed
OR
using reverse transcriptase, the enzyme must first transform RNA into DNA;

c. PCR primers stick to DNA;

d. amplify DNA;

Microarray:
e. genetic material can be detected in microarray;

f. probes of the DNA of the pathogen are placed on the chip;

g. if the pathogen DNA is complementary, there is fluorescence;

Presence of proteins: [Allow 4 max]
h. presence of the proteins can be detected by ELISA;

i. the test detects the antigens which are proteins of the pathogens;

j. it uses antibodies stuck to a plate (which capture the pathogen antigen)
OR
it detects antibodies against pathogen;

k. antibodies with an enzyme/fluorescence are used to reveal binding;

l. metabolites of the disease detected in blood/urine;

Only a few complete and detailed answers were provided by good candidates; most answers were based on previous examination sessions and mentioned some valid techniques, but failed to address the detection of the pathogen's genetic material on one hand, and its proteins on the other hand, which were specific to this session's question.