Importance of Membranes in Molecular Transport, ATP Systems
Importance of membranes in molecular transport and in ATP synthesis
The way in which a membrane is assembled decides what is allowed in and out of a cell and how it advances through the cell membrane. Certain molecules can simply pass through the cell membrane through diffusion. Diffusion is a type of passive transport meaning no energy is used for the substance to enter or leave the cell. Another way for molecules to enter the cell is through facilitated diffusion. When a molecule is simply to large to diffuse through the cell membrane it can enter the cell through a Transport Protein. Facilitated diffusion is also a form of passive transport. When a molecule is to large to diffuse through the cell membrane it may enter the cell through the process of active transport. Active transport requires that a phosphate group such as ATP assist a Transport Protein. Exocytosis is another method for larger cells to penetrate the cell membrane and enter the cell. An object or objects are enclosed within a transport vesicle and then fuse to the plasma membrane thus releasing its contents. Endocytosis is just the opposite of exocytosis. In endocytosis the plasma membrane caves in and closes off the molecules inside itself and then pinches itself away from the plasma membrane and into the cell. Three types of endocytosis are phagocytosis where the cell consumes the molecule, pinocytosis where the cell drinks the molecules, and receptor-mediated endocytosis where the membrane forms a pit and pinches closed with the needed molecules inside.
The stomata are microscopic pores bordered by guard cells in the epidermis of leaves that allows carbon dioxide to be exchanged between the environment and the interior and oxygen to exit out of the leaf and plant. The carbon dioxide then goes to the Tylakoids, flattened membrane sacs inside the chloroplast they are used to change light energy to chemical energy. The membrane that is most involved in the synthesis of ATP in photosynthesis is the thylakoid membrane. Inside the thylakoid membrane are both of the photosystems and both the electron transport chains and ATP synthase. Starting in photosystem II excited electrons from water travel along the first E.T.C., a four-protein electron transport chain, allowing H+ ions to travel from one side of the membrane to the other....