Summary Biosignaling

Biosignaling
Types of Transportation Across Membranes
• Passive transportation:
- Spontaneous
- Does not require energy
- Down the electrochemical gradient
• Active transportation:
- Non-spontaneous
- Against the electrochemical gradient: requires energy
- Primary active transport: coupled with ATP hydrolysis
- Secondary active transport: coupled with ions movement


Types of Transporters
• Channels: passive transport
- Ion channels (eg. K+ channel)
- Voltage gated (e.g voltage-gated K+ channel)
- Ligand gated (e.g nicotinic acetylcholine receptor- gated channels)

• Carriers: passive and active transport
- Facilitated diffusion (e.g. GLUT1)
- Secondary active transport (eg. Lactose transporter)
• Pumps: primary active transport
- Facilitated diffusion (e.g. P-type ATPase pump, proton pump and ABC
transporters)


Classes of Transporters
• Carriers and pumps differ in the number of solutes(substrates)
transported and the direction in which each solute moves

, Types of Transporter




Biological Role of Signal Transduction
• Cells receive signals from the environment beyond the plasma
membrane. Types of signals include:
– antigens
– hormones
– neurotransmitters
– light
– touch
– pheromones


• These signals cause changes in the cell’s composition and function,
such as:
– differentiation and antibody production
– growth in size or strength
– sexual versus asexual cell division