cellular repiration

• Passive transport relates concentration gradients, diffusion, and equilibrium.
• Passive transport predicts the direction of water movement into and out of cells.
• Passive transport describes the importance of ion channels in passive transport.
• Passive transport identifies the role of carrier proteins in facilitated diffusion.
• Cells maintain homeostasis by controlling the movement of substances across their cell membrane.
• Cells must use energy to transport some substances across the cell membrane.
• Other substances move across the cell membrane without any use of energy by the cell.
• Passive transport is the movement of substances across the cell membrane that does not require energy from the cell.
• A concentration gradient is a difference in the concentration of a substance, such as the balls, across a space.
• Equilibrium is a condition in which the concentration of a substance is equal throughout a space.
• Diffusion is the movement of a substance from an area of high concentration to an area of lower concentration caused by the random motion of particles of the substance.
• When carrier proteins are used to transport specific substances — such as amino acids and sugars — down their concentration gradient, that transport is called facilitated diffusion.
• An ion that enters the pore can cross the cell membrane without contacting the nonpolar interior of the lipid bilayer.
• The diffusion of water through a selectively permeable membrane is called osmosis.
• A more positively charged ion located outside the cell is more likely to diffuse into the cell, where the charge is negative.
• There are three possibilities for the direction of water movement: water moves out, water moves in, or there is no net water movement.
• An isotonic solution produces no change in cell volume because of osmosis.
• Like other forms of diffusion, osmosis involves the movement of a substance — water — down its concentration gradient.
• A hypertonic solution causes a cell to shrink due to osmosis.
• A hypotonic solution causes a cell to swell because of osmosis.
• Osmosis is a type of passive transport.
• The pore of an ion channel spans the thickness of the cell membrane.
• An ion channel is a transport protein with a polar pore through which ions can pass.
• The movement of a charged particle, such as an ion, across the cell membrane is influenced by the particle’s positive or negative electrical charge.
• A more negatively charged ion located inside the cell is more likely to diffuse out of the cell.
• Most cells also have a different kind of transport protein, called carrier proteins, that can bind to a specific substance on one side of the cell membrane, carry the substance across the cell membrane, and release it on the other side.
• Many substances, such as molecules and ions dissolved in the cytoplasm and in the fluid outside cells, enter or leave cells by diffusing across the cell membrane.
• Diffusion is the process by which food coloring (blue) will gradually move through uncolored gelatin (yellow), as shown in the beakers below.
• Most often, the energy needed for active transport is supplied directly or indirectly by ATP.
• Passive transport involves the movement of substances across the cell membrane without the use of energy.
• Unlike passive transport, active transport requires the cell to use energy because the substance is being moved against its concentration gradient.
• The transport of a substance across the cell membrane against its concentration gradient is called active transport.
• The sodium-potassium pump has four steps: Three sodium ions inside the cell bind to the sodium-potassium pump, the pump changes shape, transporting the three sodium ions across the cell membrane and releasing them outside the cell, two potassium ions outside the cell bind to the pump, the two potassium ions are transported across the cell membrane and are released inside the cell.
• Facilitated diffusion is a type of passive transport that involves the movement of substances across the cell membrane against their concentration gradient, requiring the cell to use energy because the substance is being moved against its concentration gradient.
• The sodium-potassium pump is a carrier protein that transports three sodium ions out of a cell and two potassium ions into the cell, requiring the cell to use energy because the substance is being moved against its concentration gradient.
• Many substances, such as proteins and polysaccharides, are too large to be transported by carrier proteins, these substances are moved across the cell membrane by vesicles.
• The movement of a substance into a cell by a vesicle is called endocytosis, the movement of a substance by a vesicle to the outside of a cell is called exocytosis.
• One of the most important membrane pumps in animal cells is a carrier protein called the sodium-potassium pump, which transports three sodium ions out of a cell and two potassium ions into the cell, requiring the cell to use energy because the substance is being moved against its concentration gradient.
• Active transport involves the movement of substances across the cell membrane against a concentration gradient, requiring the cell to use energy because the substance is being moved against its concentration gradient.
• If a cell’s sodium - potassium pumps did not function properly, the concentration of potassium ions would increase inside the cell.