The cell is taking in substances through membrane proteins, without any energy expenditure of its own. The substances naturally
follow their concentration gradient. However, they must go through the protein channels, because they are too large to squeeze through the cell membrane. This process is called
Facilitated diffusion is a diffusion mechanism facilitated by membrane transporters. it's the spontaneous passage of molecules or ions (like the passive diffusion) through a biological membrane through transport molecules (unlike passive diffusion). This process does not consume energy (like the passive diffusion) and therefore does not involve active transportation.
Facilitated diffusion. because the protein channels must help the substance get into the cell based on fitting. It's important to regulating what comes in and goes out.
Transcription begins at a gene's promoter, a specific sequence of DNA that acts as a "start" signal for a gene that is to be transcribed. Transcription ends at a sequence of bases that acts as a "stop" signal.
