transport across membranes Flashcards
(16 cards)
What are the types of movements in and out of cells through the plasma membrane?
Diffusion, facilitated diffusion, osmosis, active transport
What is diffusion?
The net movement of molecules from a high concentration to a low concentration until the molecules are equally distributed
Why is diffusion passive?
It does not require any ATP
How is the rate of diffusion increased?
A higher concentration gradient, a larger surface area, a shorter diffusion distance
What is the rate of diffusion proportional to?
(Surface area x concentration) ÷ diffusion distance
What does facilitated diffusion allow to happen?
The transport of polar molecules across membranes down a concentration gradient
What does facilitated diffusion involve the use of?
Carrier and channel proteins
How are carrier proteins similar to enzymes?
They are specific to one substrate
How are carrier proteins different from channel proteins?
Channel proteins don’t change shape whereas carrier proteins do
What is active transport?
The movement of molecules or ions through a partially permeable membrane by a carrier protein against the concentration gradient
What does active transport require?
Energy from the hydrolysis of ATP
What does the binding to the protein do?
Causes the carrier protein to change shape
What do the cells involved in active transport have a lot of?
Mitochondria
What will factors decreasing the rate of respiration also do to the rate of active transport?
Decrease it
What are some factors which decrease the rate of respiration?
Lowering the temperature, lack of oxygen, metabolic and respiratory inhibitors
What is diffusion distance?
The number of cells the molecules have to go through
