Transcript Passive Vs. Active Transport

Passive Vs. Active Transport
in Cells
What is passive transport?
• Questions: What part of a cell allows things like sugar,
water, and salt in and out of its environment?
• Cell Membrane
• Passive Transport: The movement of substances
through the cell membrane without the input of energy.
• Acts like a screen door: Air is allowed in, yet bugs are not.
• For this reason we say that it is “Semi-Permeable”
What is diffusion?
• What takes place in your body when a coach ask you to
“warm up”?
• The oxygen you are taking in is being passed to all the cells in your
body.
• What allows this process to take place?
• Diffusion: A type of passive transport where molecules move from
an area where there are relatively more of them to an area where
there are relatively fewer.
• Concentration Gradient: There is an area of high concentration and
an area of low concentraion.
• Diffusion will stop when equilibrium is reached.
What is osmosis?
• Osmosis: The diffusion of water through a cell
membrane.
• Water will leave a cell when there is not the same amount of water
inside and outside the cell.
• When plant cells lose water the cell membrane pulls away from the
cell wall.
– Why do plants become limp in the summer time?
What is active transport?
• Active Transport: When an input of energy is required to
move materials through a cell membrane. (this could
occur because the molecule is too large or because it is
moving against the concentration gradient)
– How do plant roots get their nutrients?
• There is more nitrogen in the root of a plant than in the surrounding
soil
• Plants need more nitrogen from the soil to survive
• Transport protein pulls the nutrient through the cell membrane.