Biochemistry : Toll-Like Receptors
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Example Question #1 : Toll Like Receptors
A bacterium is often recognized and attacked by the immune cells. What is true regarding this process?
Toll-like receptors (TLRs) on the bacteria signal and recruit immune cells
Toll-like receptors (TLRs) on the bacteria signal and recruit immune cells and peptidoglycan is a molecule recognized by immune cells
None of these
Peptidoglycan is a molecule recognized by immune cells
Peptidoglycan is a molecule recognized by immune cells
Toll-like receptors are special molecules that recognize specific portions of pathogens called PAMPs (pathogen associated molecular patterns). The toll-like receptors on the immune cells recognize PAMPs on the pathogen. One of the most common PAMPs recognized by toll-like receptors is peptidoglycan on the cell walls of the bacteria.
Example Question #2 : Toll Like Receptors
Which of the following is true regarding toll-like receptors?
I. They are found on pathogens
II. They are involved in both acute and chronic inflammation
III. They are not found on complements
I only
III only
II and III
I and III
II and III
Toll-like receptors found on immune cells recognize pathogens and recruit other immune cells to clear the pathogen. These toll-like receptors are found in both innate immune system (macrophages and neutrophils) and in adaptive immune system (lymphocytes). Recall that acute inflammation is mediated by neutrophils and macrophages whereas chronic inflammation is mediated by lymphocytes; therefore, toll-like receptors can activate both acute and chronic inflammation. Complements are part of the innate immune system and serve as markers (opsonins) for pathogen recognition. Complements bind to an infected cell or to an antibody-antigen complex and signal immune cells to eliminate the pathogen. They do not utilize toll-like receptors.
Example Question #3 : Toll Like Receptors
Which of the following processes will be ultimately modulated by activation of toll-like receptors?
DNA replication
Transcription
Protein phosphorylation
Translation
Transcription
Upon activation, toll-like receptors activate a transcription factor called nuclear factor kappa-light-chain-enhancer of activated B cells (NF-KB). This transcription factor ultimately activates genes in the genome that are involved in immune response. Upon activation of NF-KB, genes undergo transcription and produce mRNA which can eventually be converted to proteins that facilitate the immune response; therefore, activation of toll-like receptors (TLR's) activates transcription.
Example Question #4 : Toll Like Receptors
What are some characteristics of toll-like receptors?
I. Toll-like receptors are transmembrane proteins characterized by an extracellular domain and a cytoplasmic tail containing the toll receptor domain.
II. Toll-like receptors can be activated by viral double-stranded RNA.
III. Toll-like receptors alert immune cells to the presence of bacterial infections.
IV. Toll-like receptors are expressed in antigen presenting immune cells (dendritic cells).
I and II
II, III, and IV
II and III
I, II, III, and IV
I, II, and III
I, II, III, and IV
Toll-like receptors can be activated by bacterial components such as lipopolysaccharide, peptidoglycan, flagellin, and bacterial DNA. Toll-like receptors activate transcription factors and immune regulatory factors.Activation triggers the production of pro-inflammatory cytokines such as interleukins.
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