Answer to Question #111682 in Cell Biology for Felicia Ngubandze

Question

State and explain the transport mechanisms across the cell membrane

Answer 1

There are two types of transport: active and passive. Passive transport occurs without energy consumption, while the substance moves along the concentration gradient. With active transport, the substance moves against the concentration gradient and this process requires energy.

Types of passive trasport:

• Diffusion

Diffusion is a process of passive transport in which molecules move from an area of higher concentration to one of lower concentration.

• Osmosis

Osmosis is the movement of water across a membrane from an area of low solute concentration to an area of high solute concentration.

• Facilitated diffusion

Facilitated diffusion is a process by which molecules are transported across the plasma membrane with the help of membrane proteins.

Types of active transport:

• Primary active transport

The sodium-potassium pump maintains the electrochemical gradient of living cells by moving sodium in and potassium out of the cell. The sodium-potassium pump moves K+ into the cell while moving Na+ at a ratio of three Na+ for every two K+ ions.

• Secondary active transport

A molecule is moved down its electrochemical gradient as another is moved up its concentration gradient. While secondary active transport consumes ATP to generate the gradient down which a molecule is moved, the energy is not directly used to move the molecule across the membrane.

https://courses.lumenlearning.com/boundless-ap/chapter/transport-across-membranes/