SCIENCE
CELL BIOLOGY
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
a membrane-spanning protein
|
|
a surface protein
|
|
a phospholipid
|
|
a carbohydrate
|
Detailed explanation-1: -Facilitated diffusion. Some molecules, such as carbon dioxide and oxygen, can diffuse across the plasma membrane directly, but others need help to cross its hydrophobic core. In facilitated diffusion, molecules diffuse across the plasma membrane with assistance from membrane proteins, such as channels and carriers.
Detailed explanation-2: -Facilitated diffusion therefore allows polar and charged molecules, such as carbohydrates, amino acids, nucleosides, and ions, to cross the plasma membrane.
Detailed explanation-3: -Facilitated Diffusion Requires Membrane Carrier Proteins Facilitated diffusion is also calledcarrier-mediated diffusion because a substance transported in this manner diffuses through the membrane with the help of a specific carrier protein. That is, the carrierfacilitates diffusion of the substance to the other side.
Detailed explanation-4: -Facilitated diffusion requires membrane proteins to transport biological molecules. Simple diffusion is one that occurs unassisted by membrane proteins. Since membrane proteins are needed for transport in facilitated diffusion, the effect of temperature is often more pronounced than in simple diffusion.
Detailed explanation-5: -Channel proteins, gated channel proteins, and carrier proteins are three types of transport proteins that are involved in facilitated diffusion. A channel protein, a type of transport protein, acts like a pore in the membrane that lets water molecules or small ions through quickly.