Detecting Pathogens 7A Flashcards
What is an antigen?
any molecule that may trigger an immune response
What is a pathogen?
an agent that causes disease
Where are MHC I markers present?
MHC Class I markers are expressed on all nucleated cells in the body. Therefore, virtually all cells in the human body except for those without a nucleus (e.g. red blood cells) express MHC Class I markers.
Where MHC Class II markers found?
MHC Class II markers are found on specialised cells of the immune system. This includes antigen presenting cells
What is the distinction between an autoimmune disease and a allergy
In autoimmunity, the immune system attacks your body’s cells instead of protecting them. With allergies, the immune system recognizes food or pollen as dangerous and acts like it does when trying to kill a virus or bacteria.
Major histocompatibility complexes are a type of protein embedded in cell membranes. Explain how a single gene can produce many different proteins?
Post-transcriptional modifications to the transcribed pre-mRNA through alternative splicing can produce many different strands of mature mRNA, leading to the production of many different proteins.
Rifampicin is a type of antibiotic which inhibits bacterial RNA polymerase. Identify and outline the process which rifampicin inhibits.
Rifampicin inhibits the process of transcription.Transcription involves the unwinding of the DNA helix which allows for the binding of RNA polymerase to the promoter region.RNA polymerase then synthesises a strand of pre-mRNA with the use of complementary RNA molecules.Transcription is terminated when RNA polymerase reaches a termination sequence.
Clarithromycin and doxycycline are two types of antibiotics which target bacterial ribosomes. Identify and outline the process inhibited by these antibiotics.
These antibiotics inhibit the process of translation.1Translation begins with the binding of a mRNA molecule to a ribosome, with the start codon initiating the process.2tRNA molecules with anticodons complementary to the mRNA strand transport specific amino acids to the ribosome, which are added to the growing polypeptide chain via peptide bonds.3Translation terminates once the stop codon is recognised and the polypeptide chain is released.4
Provided that the virus is composed of RNA, suggest how viral proteins may be produced within the infected cell.
The RNA may be in the form of mRNA, which can be used to directly produce viral proteins via the process of translation.1
Explain the difference between the patterns of growth of bacteria and viruses after infection.
After the accumulation of viruses inside a cell and the weakening of the cell’s cytoskeleton, the cell bursts, releasing the viral particles into the extracellular environment. Therefore, every time viruses burst from cells, there is a sudden increase in the number of extracellular viruses.1Conversely, bacteria are able to continuously replicate in the extracellular environment, resulting in a smooth exponential curve.2
