April 23, 2020
Account for the movement of substances across membrane using the concepts of active transport.
Mechanism of active transport
Active transport is the movement of molecules from lower concentration region to higher concentration region ⏩ against concentration gradient.
Active transport is the way to transport molecules across cell membrane with the use of energy (ATP).
👆🏻 This photo showing how active transport works.
Na/K pump - example of active transport
👆🏻 This photo showing how active transport assist the transport of Na+ and K+ against concentration gradient.
- In extracellular space, the concnetration of sodium ion (Na+) is higher than intracellular space while the concentration of potassium ion (K+) is lower than intracellular space.
- Na+ transported into cell against concentration gradient through active transport with the use of energy from ATP.
- K+ transported out of cell against concentration gradient through active transport with the use of energy from ATP.
Here are several misconceptions on HKDSE Biology student 👀
1. Active transport ❌ Facilitated diffusion
- Both active transport and facilitated diffusion used protein embedded in cell membrane. Yet, active transport transport molecules against concentration gradient while facilitated diffusion transport molecules down concentration gradient.
2. Active transport use carrier protein
- Active transport use carrier protein to transport ions while channel protein is used in facilitated diffusion.
That's the end of this topic 👏🏻
References
- Thomas, B. & Chris, H. (2013) Hong Kong DSE Biology Critical Guide. Yellowreef Limited.
- Active transport review (article). (n.d.). Retrieved from https://www.khanacademy.org/science/high-school-biology/hs-energy-and-transport/hs-passive-and-active-transport/a/hs-active-transport-review