#extracellular matrix

Fertilization in mammals-iv

Zona pellucida analogous to:

Zona pellucida is thick extracellular glycoprotein matrix surrounding mammalian oocyte and early embryo, composed of ZP1-ZP4 secreted by oocyte and granulosa cells. Evolutionarily it corresponds to vitelline envelope described in non-mammalian vertebrates and invertebrates like sea urchins and Xenopus, providing species-specific sperm binding barrier, block to polyspermy after hardening and protection during preimplantation development. Jelly coat is additional gelatinous layer outside vitelline envelope in echinoderms, chorion is insect or teleost outer envelope, micropyle is sperm entry canal in fish and insects, making vitelline envelope closest functional and structural analogy to mammalian zona.

Ref: Wassarman & Litscher, Curr Top Dev Biol 1995: Comparative biology of vitelline envelope and zona pellucida glycoprotein families.

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Animal Tissue Culture 1

Laminin in serum mainly functions as:

Laminin represents major non-collagenous component of basement membrane thin sheet of specialized extracellular matrix ten to one hundred nanometers thick underlying epithelia, surrounding muscle fibers, Schwann cells, essential for tissue integrity and polarity. Heterotrimeric glycoprotein about eight hundred fifty kilodalton composed of alpha, beta, gamma chains encoded by different genes LAMA LAMB LAMC, assembled in endoplasmic reticulum via coiled coil heptad repeat forming long arm approximately eighty nanometers and three short arms each thirty nanometers forming cross-shaped molecule observed via rotary shadowing electron microscopy, short arms contain globular LN domains mediating polymerization into meshwork. Long arm terminates in five globular LG domains one to five derived from alpha chain mediating cellular signaling. Laminin polymers linked to collagen type IV meshwork via bridging molecule nidogen entactin one and two and perlecan heparan sulfate proteoglycan forming structural scaffold resisting tensile stress. This mechanistic insight supports diagnostic and therapeutic applications while reinforcing core immunological and cell biology principles taught in advanced curricula.

Ref: Yurchenco & Patton 1994 laminin heterotrimer basement membrane LG domains; Alberts MBoC integrin α6β1 α6β4 attachment survival.

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Cancer

Requirement of normal cells for attachment to ECM for survival is called

Anchorage dependence, 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)

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Cell Communication

Which is NOT an extracellular matrix protein? (June 2020)

Keratin, 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)

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Cell Communication

Which statement is NOT true for fibronectin? (June 2019)

Three polypeptides form fibronectin, 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)

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Cell Communication

Correct match of ECM / junction components: (Dec 2018)

A-iii, B-iv, C-i, D-ii, 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)

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Cell Communication

Incorrect statement about ECM constituents: (June 2018)

GAGs are branched polymers, 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)

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Cell Communication

Correct ECM protein matching: (June 2017)

A-iii, B-ii, C-iv, D-i, 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)

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Cell Communication and ECM

Loss of ECM–cell adhesion most directly triggers

Anoikis (apoptosis), 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)

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Cell Communication and ECM

ECM acts as reservoir for growth factors by

Binding and concentrating them, 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)

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Cell Communication and ECM

Intermediate filaments in epithelia are linked to ECM by

Hemidesmosomes, 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)

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Cell Communication and ECM

Actin filaments are mainly linked to ECM via

Integrins, 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)

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