Innate Immunity Flashcards
What are the two outcomes of a ligand binding to its receptor on a cell’s surface?
- A response is triggered in the cell, initiating some change.
- The internal portion of the receptor becomes modified.
Identify three structures detected by NOD-like receptors.
- Peptidoglycan
- Flagellin
- Bacterial secretions
Compounds recognized by TLRs anchored in the cytoplasmic membrane and facing the outside of the cell normally include which of the following?
- Lipoproteins
- Flagellin
- Peptidoglycan
When a cell’s cytoplasmic PRRs detect viral RNA, the cell responds by synthesizing and secreting a(n) ________.
Interferon
PRRs in a cell’s cytoplasm enable the cell to monitor ______ for signs of invasion.
its own internal contents
Why are RIG-like receptors (RLRs) located inside most cell types?
They represent an important early-warning system for virally infected cells, which can alert neighboring cells a virus is present.
NOD-like receptors (NLRs) are cytoplasmic proteins that detect microbial components. Why would a cell need detectors on the inside, rather than the outside?
Such detectors could alert the cell when its borders have been breached.
How is the lectin pathway of the complement system activated?
Mannose-binding lectin (MBL), which binds to certain arrangements of mannose, a monosaccharide commonly found on the surface of bacteria and fungi. Once MBL binds, it interacts to create C3 convertase, triggering the cascade.
How is the classical pathway of the complement system triggered?
When multiple antibodies bind to an antigen (creating an antigen-antibody complex), they interact with the same components involved in the lectin pathway forming a C3 convertase and triggering the cascade.
How is the alternative pathway of the complement system triggered?
C3b binds to foreign cell surfaces; other host proteins then bind to that C3b, eventually forming a C3 convertase, thereby triggering the cascade.
In general, a complement system protein gets activated when it ______.
splits into two smaller fragments
A cell enters an antiviral state after detecting interferons by producing inactive antiviral proteins (iAVPs). What triggers these iAVPs to become active and cause apoptosis?
viral dsRNA
Where do most cells have pattern recognition receptors (PRRs)?
In the cytoplasm
What kind of PRR monitors a cell’s surroundings?
TLR (toll-like receptors)
RIG-like receptors (RLRs) detect what specific features of dsRNA?
- Viral RNA will often form double-stranded areas, whereas eukaryotic RNA does not.
- Viral RNA isn’t capped at the 5’ end (as eukaryotic RNA is)–it has 5’ phosphate groups exposed instead.
