9 public questions tagged with this topic.
Memory B-cells are responsible for immunological memory, allowing a faster and stronger response upon second exposure to the same antigen.
Ref: NCERT Class 12 Biology Chapter 7: Human Health and Disease Drugs and Alcohol Abuse - Opioids Cannabinoids Cocaine Adolescence
Memory B-cells retain information about pathogens and provide long-term immunity upon re-exposure.
Ref: NCERT Class 12 Biology Chapter 7: Human Health and Disease Drugs and Alcohol Abuse - Opioids Cannabinoids Cocaine Adolescence
Graft rejection is mediated by cell-mediated immunity, which involves T-lymphocytes recognizing and attacking foreign tissues.
Ref: NCERT Class 12 Biology Chapter 7: Human Health and Disease Immunity - Innate Immunity - Barriers and Interferons
The adaptive immune system involves B-lymphocytes and T-lymphocytes, providing a specific response and memory against pathogens.
Ref: NCERT Class 12 Biology Chapter 7: Human Health and Disease Common Diseases - Helminthic and Fungal - Ascariasis Filariasis Ringworm
CRISPR-Cas systems confer heritable sequence-specific defense fundamentally distinct from innate restriction-modification. Following initial infection, adaptation complex Cas1-Cas2 captures viral or plasmid protospacer DNA and integrates new spacer into leader-proximal end of CRISPR array. Upon reinfection, array transcribed and processed into crRNAs that guide Cas nucleases to complementary invader DNA or RNA for targeted cleavage. Spacer acquisition creates immunological memory improving resistance with repeated encounters, fulfilling criteria for Lamarckian inheritance. This adaptive character underpins repurposing for genome editing, while providing bacteria population-level immunity, spacer diversity, and protection against lytic phages preserving microbial ecosystems.
Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 5: CRISPR – Adaptive Immunity in Prokaryotes
CRISPR immunity proceeds through adaptation, expression and interference stages. During adaptation, Cas1-Cas2 heterohexamer complex captures fragments of invading phage or plasmid DNA and integrates them as new spacers at leader end of CRISPR array. This spacer acquisition step records immunological memory for future defense. Cas1 is metal-dependent integrase cutting and ligating DNA, Cas2 provides essential structural scaffold. Interference later uses Cas9 guided by crRNA, while spacer incorporation entirely depends on Cas1-Cas2, making it essential for naive adaptation and primed acquisition pathways.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.
Antigen presentation by dendritic cells, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.
Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)
Innate immune receptors are germline-encoded and recognize conserved pathogen-associated molecular patterns rather than specific antigens. This limited repertoire allows rapid responses but lacks the exquisite specificity and memory of adaptive immunity. Pattern-recognition receptors include Toll-like receptors, NOD-like receptors, RIG-I-like receptors and C-type lectins that trigger inflammatory and antimicrobial programs within minutes to hours of infection.
Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)
Innate immune receptors are germline-encoded and recognize conserved pathogen-associated molecular patterns rather than specific antigens. This limited repertoire allows rapid responses but lacks the exquisite specificity and memory of adaptive immunity. Pattern-recognition receptors include Toll-like receptors, NOD-like receptors, RIG-I-like receptors and C-type lectins that trigger inflammatory and antimicrobial programs within minutes to hours of infection.
Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)
