Palisade cell Palisade cell Palisade cells are plant cells located in leaves, right below the epidermis and cuticle. They are vertically elongated, a different shape from the spongy mesophyll cells beneath them in the leaf. Their chloroplasts absorb a major portion of the light energy used by the leaf. Palisade cells occur in dicotyledonous plants, and also in the net-veined monocots, the Araceae and Dioscoreaceae. Palisade cells contain the largest number of chloroplasts per cell, which makes them the primary site of photosynthesis in the leaves of those plants that contain them, converting the energy in light to the chemical energy of
Cell signaling activated, resulting in constitutively activated downstream signals. For several types of intercellular signaling molecules that are unable to permeate the hydrophobic cell membrane due to their hydrophilic nature, the target receptor is expressed on the membrane. When such a signaling molecule activates its receptor, the signal is carried into the cell usually by means of a second messenger such as cAMP. In some cases, receptor activation caused by ligand binding to a receptor is directly coupled to the cell's response to the ligand. For example, the neurotransmitter GABA can activate a cell surface receptor that is part of an ion