How Various Mechanisms By Which Substances Cross The Cell Me :: essays research papers

Homeostasis is essential to the cell’s survival. The cell membrane is responsible for homeostasis. The membrane has a selective permeability which means what moves in and out of the cell is regulated. Amino acids, sugars, oxygen, sodium, and potassium are examples of substances that enter the cell. Waste products and carbon dioxide are removed from the cell. All of these substances cross the membrane in a variety of ways. From diffusion and osmosis, to active transport the traffic through the cell membrane is regulated.   Ã‚  Ã‚  Ã‚  Ã‚  Diffusion is the movement of molecules form one area of higher concentration to an area of lower concentration. Concentration gradient causes the molecules to move from higher concentration to a lower concentration. The side of the membrane that has the higher concentration is said to have the concentration gradient. It drives diffusion because substances always move down their concentration gradient. The pressure gradient also plays a role in diffusion. Where this is a pressure gradient there is motion of molecules. The pressure gradient is a difference in pressure between two different points. If the concentration of one side of the membrane is greater than the molecules will travel from the higher to lower concentration. Eventually there will be a dynamic equilibrium and there will be no net movement of molecules from one side to the other.   Ã‚  Ã‚  Ã‚  Ã‚  Osmosis is the diffusion of water. Like diffusion, the water moves from a region of higher water potential to a region of lower water potential. Solutions have three different stages that the solutes can be classified in: isotonic, hypertonic, and hypotonic. Isotonic is when the solutions have equal amounts of solutes. Like equilibrium, there is no net change in the amount of water in either solution. When the solutions have different concentration of solutes then the one with less solute is hypotonic and the one with more solute is hypertonic. Hypotonic takes in the solute from the hypertonic side that gives away the solute. There will be a net movement in these types of solution. The molecules will move from the hypotonic solution into the hypertonic solution.   Ã‚  Ã‚  Ã‚  Ã‚  The third way a substance can cross the cell membrane is through facilitated diffusion. This occurs when special carrier proteins carry solutes dissolved in the water across the membrane by using active transport. When the concentration gradient can not allow travel from one side of the membrane to the other fast enough for the cell’s nutritional needs, then facilitated diffusion is used. The transport protein is specialized for the solute it is carrying, just as enzymes are specialized for their substrate. The transport protein can be How Various Mechanisms By Which Substances Cross The Cell Me :: essays research papers Homeostasis is essential to the cell’s survival. The cell membrane is responsible for homeostasis. The membrane has a selective permeability which means what moves in and out of the cell is regulated. Amino acids, sugars, oxygen, sodium, and potassium are examples of substances that enter the cell. Waste products and carbon dioxide are removed from the cell. All of these substances cross the membrane in a variety of ways. From diffusion and osmosis, to active transport the traffic through the cell membrane is regulated.   Ã‚  Ã‚  Ã‚  Ã‚  Diffusion is the movement of molecules form one area of higher concentration to an area of lower concentration. Concentration gradient causes the molecules to move from higher concentration to a lower concentration. The side of the membrane that has the higher concentration is said to have the concentration gradient. It drives diffusion because substances always move down their concentration gradient. The pressure gradient also plays a role in diffusion. Where this is a pressure gradient there is motion of molecules. The pressure gradient is a difference in pressure between two different points. If the concentration of one side of the membrane is greater than the molecules will travel from the higher to lower concentration. Eventually there will be a dynamic equilibrium and there will be no net movement of molecules from one side to the other.   Ã‚  Ã‚  Ã‚  Ã‚  Osmosis is the diffusion of water. Like diffusion, the water moves from a region of higher water potential to a region of lower water potential. Solutions have three different stages that the solutes can be classified in: isotonic, hypertonic, and hypotonic. Isotonic is when the solutions have equal amounts of solutes. Like equilibrium, there is no net change in the amount of water in either solution. When the solutions have different concentration of solutes then the one with less solute is hypotonic and the one with more solute is hypertonic. Hypotonic takes in the solute from the hypertonic side that gives away the solute. There will be a net movement in these types of solution. The molecules will move from the hypotonic solution into the hypertonic solution.   Ã‚  Ã‚  Ã‚  Ã‚  The third way a substance can cross the cell membrane is through facilitated diffusion. This occurs when special carrier proteins carry solutes dissolved in the water across the membrane by using active transport. When the concentration gradient can not allow travel from one side of the membrane to the other fast enough for the cell’s nutritional needs, then facilitated diffusion is used. The transport protein is specialized for the solute it is carrying, just as enzymes are specialized for their substrate. The transport protein can be