MICB 302 Exam Study Guide Questions
All Answered Correctly 2026/2027 Set.
Explain the how a few pattern recognition receptors (PRRs) can collectively recognize most
pathogens. - Answer PRRs are germ-line encoded and do not undergo somatic recombination,
therefore do not have specificity like T/ B cells.
-PRRs can recognize PAMPS which are essentially non-cellular structures present on pathogens,
meaning that most pathogens are readily identified by PRRs
Explain the different types of PRRs.
-Membrane bound phagocytic receptors (opsonic and non-opsonic)
-how does phagocytosis occur, what does it induce - Answer -phagocytose as a result of
recognition
-binding to target particle leads to aggregating and signaling of multiple phagocytic receptors,
leading to remodeling of lipids/ actin, which allows for endo/phagocytosis
opsonic:
-indirect pathogen recognition
-bind pathogens coated with IgG or complement as a result of their Fc receptors or complement
receptors respectively.
non-opsonic:
-direct pathogen recognition
-scavenger receptors and C-type lectins that recognize (-) charged ligand and carbs respectively.
-bind the surface of bacterial/ apoptotic cells
Induces:
-cytokines (recruitment, increased leuk production, effector molecule expression, fever),
-chemokines,
-co-stim factors,
-adhesion molecules.
Explain the different types of PRRs.
-Membrane-bound signalling receptors (TLRs--> specifically, their activation and signal
transduction that follows)
-what does TLR4 recognize - Answer -mast, mac, neutrophil, B cell, DC, some epi cells
,-form homodimers pr heterodimers upon binding target
Activation:
1. LRR (leucine rich) binds ligand, inducing dimer formation
2. TIR domain propagates a signal by interacting with cytoplasmic signalling molecules
3. expression of transcription factors such as NF-kB, Irfs is induced
4. inflammatory cytokines, IFNs, TNF-a, IL-1/6, antimicrobial peptides, chemotactic factors can
all be induced.
TLR4--> LPS
Explain the different types of PRRs.
-Cytosolic signalling receptors (NLR, RLR, cGAS-STING)
-process and result of recognition - Answer NOD-like receptors:
1.LRR (leucine) recognizes/ binds fragmented PG
2.other domains induce inflammatory cytokines
Rig-1 like receptors:
1.helicase domain detects/ binds viral RNA in cytoplasm
2.another domain interacts with mitochondrial anti-viral signalling proteins (MAVs),
3.leading to Irfs transcription factor activation, and finally Type I IFNs.
cGAS-STING
1. detects cytosolic DNA
2. catalyzes production of cGAMP
3. cGAMP binds STING, leading to activation of Irf3
4. Irf3 is a transcription factor that increases expression of IFN a/B
Explain the different types of PRRs.
-soluble proteins, or "acute-phase response" proteins (MBL, CRP, LBP)
-what they recognize and pathway of activation - Answer MBL (mannose binding lectin)
-quick and dirty lectin pathway
1. recognizes/ binds mannose on surfaces
2. activates complement via MASP (MBL- serine protease) lectin pathway
3. works as opsonins to enhance Mac phagocytosis
, CRP (C-reactive protein)
1. recognizes/ binds phosphocholine on surfaces
2. activates complement via C1q early complement protein
3. acts as opsonins
LBP (LPS-binding protein)
1.recognizes LPS by extracting it
2.transfers LPS to CD14
3. CD14 transfers LPS to TLR4
4. TLR4 initiates signal (NF-kB, Irfs, cytokines, apoptosis etc)
Explain how certain soluble PRRs that act like evolutionary early forms of antibody in terms of
pathogen recognition, opsonisation and complement activation. - Answer The C1q early
complement protein also works to activate complement with Ab that opsonize.
-some Abs have opsonization abilities much like MBL and CRP
Describe the structure and location of signalling PRRs.
-TLRs
-NLRs
-RLRs - Answer TLRs (membrane bound P.M. or endo)
-3 domains:
--> extracellular leucine rich repeats
-->single pass transmembrane domain
-->cytoplasmic tail with TIR domain for signal propagation
NLRs (cytosolic)
-2 domains:
-->extracellular leucine rich repeats
-->signal transduction domain
RLSs (cytosolic)
-2 domains:
-->extracellular helicase domain
All Answered Correctly 2026/2027 Set.
Explain the how a few pattern recognition receptors (PRRs) can collectively recognize most
pathogens. - Answer PRRs are germ-line encoded and do not undergo somatic recombination,
therefore do not have specificity like T/ B cells.
-PRRs can recognize PAMPS which are essentially non-cellular structures present on pathogens,
meaning that most pathogens are readily identified by PRRs
Explain the different types of PRRs.
-Membrane bound phagocytic receptors (opsonic and non-opsonic)
-how does phagocytosis occur, what does it induce - Answer -phagocytose as a result of
recognition
-binding to target particle leads to aggregating and signaling of multiple phagocytic receptors,
leading to remodeling of lipids/ actin, which allows for endo/phagocytosis
opsonic:
-indirect pathogen recognition
-bind pathogens coated with IgG or complement as a result of their Fc receptors or complement
receptors respectively.
non-opsonic:
-direct pathogen recognition
-scavenger receptors and C-type lectins that recognize (-) charged ligand and carbs respectively.
-bind the surface of bacterial/ apoptotic cells
Induces:
-cytokines (recruitment, increased leuk production, effector molecule expression, fever),
-chemokines,
-co-stim factors,
-adhesion molecules.
Explain the different types of PRRs.
-Membrane-bound signalling receptors (TLRs--> specifically, their activation and signal
transduction that follows)
-what does TLR4 recognize - Answer -mast, mac, neutrophil, B cell, DC, some epi cells
,-form homodimers pr heterodimers upon binding target
Activation:
1. LRR (leucine rich) binds ligand, inducing dimer formation
2. TIR domain propagates a signal by interacting with cytoplasmic signalling molecules
3. expression of transcription factors such as NF-kB, Irfs is induced
4. inflammatory cytokines, IFNs, TNF-a, IL-1/6, antimicrobial peptides, chemotactic factors can
all be induced.
TLR4--> LPS
Explain the different types of PRRs.
-Cytosolic signalling receptors (NLR, RLR, cGAS-STING)
-process and result of recognition - Answer NOD-like receptors:
1.LRR (leucine) recognizes/ binds fragmented PG
2.other domains induce inflammatory cytokines
Rig-1 like receptors:
1.helicase domain detects/ binds viral RNA in cytoplasm
2.another domain interacts with mitochondrial anti-viral signalling proteins (MAVs),
3.leading to Irfs transcription factor activation, and finally Type I IFNs.
cGAS-STING
1. detects cytosolic DNA
2. catalyzes production of cGAMP
3. cGAMP binds STING, leading to activation of Irf3
4. Irf3 is a transcription factor that increases expression of IFN a/B
Explain the different types of PRRs.
-soluble proteins, or "acute-phase response" proteins (MBL, CRP, LBP)
-what they recognize and pathway of activation - Answer MBL (mannose binding lectin)
-quick and dirty lectin pathway
1. recognizes/ binds mannose on surfaces
2. activates complement via MASP (MBL- serine protease) lectin pathway
3. works as opsonins to enhance Mac phagocytosis
, CRP (C-reactive protein)
1. recognizes/ binds phosphocholine on surfaces
2. activates complement via C1q early complement protein
3. acts as opsonins
LBP (LPS-binding protein)
1.recognizes LPS by extracting it
2.transfers LPS to CD14
3. CD14 transfers LPS to TLR4
4. TLR4 initiates signal (NF-kB, Irfs, cytokines, apoptosis etc)
Explain how certain soluble PRRs that act like evolutionary early forms of antibody in terms of
pathogen recognition, opsonisation and complement activation. - Answer The C1q early
complement protein also works to activate complement with Ab that opsonize.
-some Abs have opsonization abilities much like MBL and CRP
Describe the structure and location of signalling PRRs.
-TLRs
-NLRs
-RLRs - Answer TLRs (membrane bound P.M. or endo)
-3 domains:
--> extracellular leucine rich repeats
-->single pass transmembrane domain
-->cytoplasmic tail with TIR domain for signal propagation
NLRs (cytosolic)
-2 domains:
-->extracellular leucine rich repeats
-->signal transduction domain
RLSs (cytosolic)
-2 domains:
-->extracellular helicase domain
