Cellular Junctions
Help Questions
GRE › Cellular Junctions
Which of the following statements is NOT TRUE about gap junctions?
Gap junctions prevent molecules and ions from traveling between cells in the extracellular space.
Gap junctions form channels that are comprised of connexin proteins.
Gap junctions contribute to electrical coupling of adjacent cells.
Gap junctions have some functionality of permitting cells to adhere to one another.
Gap junctions permit the travel of small molecules back and forth between adjacent cells.
Explanation
"Gap junctions prevent molecules and ions from traveling between cells in the extracellular space" is incorrect because this describes the function of tight junctions. Gap junctions electrically couple two cells by permitting the formation of small channels that connect two cells.
Which of the following statements is NOT TRUE about gap junctions?
Gap junctions prevent molecules and ions from traveling between cells in the extracellular space.
Gap junctions form channels that are comprised of connexin proteins.
Gap junctions contribute to electrical coupling of adjacent cells.
Gap junctions have some functionality of permitting cells to adhere to one another.
Gap junctions permit the travel of small molecules back and forth between adjacent cells.
Explanation
"Gap junctions prevent molecules and ions from traveling between cells in the extracellular space" is incorrect because this describes the function of tight junctions. Gap junctions electrically couple two cells by permitting the formation of small channels that connect two cells.
What is the main purpose of gap junctions?
Allows molecules and ions to travel between cells
Prevents water from moving between cells
Prevents cells from separating from one another
Allows large molecules to move between cells
Explanation
Gap junctions can be thought of as small tunnels between cells. They allow for the immediate transport of ions and molecules between the cells. Gap junctions are prominent in cardiac myocytes, and help spread action potentials via electrical synapses to coordinate the contraction of the heart.
What is the main purpose of gap junctions?
Allows molecules and ions to travel between cells
Prevents water from moving between cells
Prevents cells from separating from one another
Allows large molecules to move between cells
Explanation
Gap junctions can be thought of as small tunnels between cells. They allow for the immediate transport of ions and molecules between the cells. Gap junctions are prominent in cardiac myocytes, and help spread action potentials via electrical synapses to coordinate the contraction of the heart.
What are the two major proteins that comprise tight junctions**,** cellular junctions that prevent fluids from traveling between cells and generally contribute to morphology by holding cells together?
Claudins and occludins
Claudins and adherins
Occludins and connexins
Connexins and integrins
Claudins and protocadherins
Explanation
While each of the proteins listed contribute to cell structure and function, the tight junction requires claudins and occludins to anchor the cytoskeleton of two adjacent cells to one another. These are the primary structural components of tight junctions.
Which of the following proteins forms channels that permit electrical communication between cells across gap junctions?
Connexin
Cadherin
Ephrin
Tubulin
Catenin
Explanation
Most of the other proteins listed are structural, but do not form any kind of pore or channel through which an electrical message can cross. Connexins are required for this function of gap junctions.
What are the two major proteins that comprise tight junctions**,** cellular junctions that prevent fluids from traveling between cells and generally contribute to morphology by holding cells together?
Claudins and occludins
Claudins and adherins
Occludins and connexins
Connexins and integrins
Claudins and protocadherins
Explanation
While each of the proteins listed contribute to cell structure and function, the tight junction requires claudins and occludins to anchor the cytoskeleton of two adjacent cells to one another. These are the primary structural components of tight junctions.
Which of the following proteins forms channels that permit electrical communication between cells across gap junctions?
Connexin
Cadherin
Ephrin
Tubulin
Catenin
Explanation
Most of the other proteins listed are structural, but do not form any kind of pore or channel through which an electrical message can cross. Connexins are required for this function of gap junctions.
Adherens junctions are specialized cell junctions that form by linking the to transmembrane proteins known as .
actin cytoskeleton . . . cadherins
intermediate filament cytoskeleton . . . integrins
microtubule cytoskeleton . . . integrins
microtubule cytoskeleton . . . cadherins
Explanation
Adherens junctions are formed by linking the actin cytoskeleton to transmembrane proteins known as cadherins. Cadherins are capable of interacting with other cadherins from neighboring cells on the exoplasmic face of the cell membrane. This interaction forms a physical link essentially connecting the actin cytoskeletons of the two adjacent cells, thus promoting force transduction.
Desmosomes are another type of cell junction that link the intermediate filaments of the cytoskeleton to cadherins.
Adherens junctions are specialized cell junctions that form by linking the to transmembrane proteins known as .
actin cytoskeleton . . . cadherins
intermediate filament cytoskeleton . . . integrins
microtubule cytoskeleton . . . integrins
microtubule cytoskeleton . . . cadherins
Explanation
Adherens junctions are formed by linking the actin cytoskeleton to transmembrane proteins known as cadherins. Cadherins are capable of interacting with other cadherins from neighboring cells on the exoplasmic face of the cell membrane. This interaction forms a physical link essentially connecting the actin cytoskeletons of the two adjacent cells, thus promoting force transduction.
Desmosomes are another type of cell junction that link the intermediate filaments of the cytoskeleton to cadherins.