GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Extracellular Matrix
Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology
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Example Questions
Example Question #1 : Extracellular Matrix
Which of the following proteins are abundant in the extracellular matrix?
Tubulin
Actin
Myosin
Collagen
Collagen
Actin and tubulin, which forms microtubules, are components of the cytoskeleton. While the extracellular matrix is linked to the cytoskeleton, these proteins are not large components of the matrix. Myosin is a motor protein that largely interacts with actin in muscle tissue. Collagens are the most abundant proteins in the extracellular matrix and have many important functions, including helping maintain cell and tissue structure.
Example Question #1 : Extracellular Matrix
Which of the following proteins is a transmembrane protein responsible for anchoring the extracellular matrix (ECM)?
Collagen
Laminin
Fibronectin
Integrins
Integrins
The only choice that is actually a transmembrane protein is "integrins." This class of protein has several important functions, including anchoring the extracellular matrix to the cell. Integrins serve as the connection between the actin cytoskeleton and the extracellular matrix. Integrins directly interact with fibronectins to help hold important proteins, such as collagens and laminins, in place. These proteins, however, are located outside of the cell and are not embedded in the membrane.
Example Question #1 : Extracellular Matrix
Which of the following is correct about integrins?
None of the other answers are correct
They promote conjugative pili firing through motile force during bacterial conjugation
They synthesize fibronectin, vitronectin, collagen, and laminin
They anchor the cell to the extracellular matrix (ECM) and relay signals from the ECM to the cell
They facilitate integration of foreign DNA into a host genome by homologous recombination
They anchor the cell to the extracellular matrix (ECM) and relay signals from the ECM to the cell
The correct answer is that integrins anchor the cell to the extracellular matrix (ECM) and relay signals from the ECM to the cell. Integrins are transmembrane receptors that bind ECM ligands such as fibronectin, vitronectin, collagen, and laminin to relay messages to the cell, ultimately regulating transcription of genes involved in the cell cycle, cell shape, and motility.
Example Question #2 : Extracellular Matrix
Which of the following is the primary structural component of the basal lamina?
Microfilaments
Type IV collagen
Laminins
Entactin
Integrins
Type IV collagen
Type IV collagen is the major component of the basal lamina, which is a crucial sub-foundation for many tissue types and epithelia. Laminins and entactin are found in the basal lamina, but there is more Type IV collagen. Integrins and microfilaments are proteins with important structural functions in other contexts.
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