Membranes â¢ Provide barrier function â Extracellular â Organelles â¢ Barrier can be overcome by âtransport proteinsâ â To mediate transmembrane movements of ions, Na + , K + â Nutrients, glucose, amino acids etc. â Water (aquaporins).
Boron is a chemical element with symbol B and atomic number 5. Produced entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, it is a low-abundance element in the Solar system and in the Earth's crust.
Boron has three valence electrons. It is in group 13. 1st energy level ------- 2 e-. 2nd energy level-------8 e-. 3rd energy level ------3 e-. Outermost energy level is the the 3rd energy level and it has three electrons. Valence electrons are the electrons in the last energy level of an atom.