What are 3 driving forces across the membrane?
- Chemical Force: Higher concentration to lower
- Electrical force: Opposite charge attracts while same charge repels
- Electrochemical force: Combination of both chemical and electrical
What are 5 types of transport?
- Simple diffusion
- Facilitated diffusion
- Diffusion through channels
- Primary active transport
- Secondary active transport
What factors affect Simple Diffusion?
- Lipid solubility
- Concentration gradient
- Surface Area
- Particles with small size and regular shape
- Membranes with relatively thin wall
What factors affect Facilitated Diffusion?
- Rate of transport of each carrier
- Number of carriers
- Concentration Gradient
Function: Uses ATP directly for molecule transport (to push from low to high concentration)
Primary active transport
Function: Uses electrochemical gradient for molecule transport
When 2 molecules are moving in the same direction in Secondary active transport, this is called
When 2 molecules are moving in different direction in active transport this is called
Definition: Diffusion of water through a membrane, always passive, unaffected by electric charge on cells
Definition: same concentration (no net water movement, cell will remain the same)
Definition: higher concentration (water gets out of cells, causing it to shrink)
Definition: Lower concentration (water gets in, causing the cell to swell or burst)
Function: Molecules enter the cells by vesicle formation
Function: Molecules are packaged into secretory vesicles inside the cell and released into the extracellular fluid
Endocytosis + Exocytosis =
3 factors affecting the strength of response
What happens in Upregulation?
Receptor # increases
What happens in down-regulation?
Receptor # decreases
What are 3 types of Chemical messanger?
- Paracrines: Target neighboring cells
- Neurotransmitters: Communication between neuron and target cell (released from Neurons)
- Hormones: travels through blood to target cell (released from endocrine gland)
Function: Receptors are found in the cytosol or nucleus
Binding of receptor will result in gene activation or deactivation
Signal transduction consist of
- Intracellular mediated response
- Membrane bound receptor mediated response
Three type of membrane bound receptors
- Channel linked receptors
- Enzyme linked receptors
- G protein coupled receptors
Function: ligand binding causes the ion channel to open or close
Channel linked receptors
Function: Ligand binding activaties the enzyme which will trigger cell response
Opening or closing of ion channels
Activating second messenger system
GPCR (G protein coupled receptors)
Channel linked receptors are
- fast ligand-gated channels...
- receptors & channels are on the same protein
Enzyme linked receptors have...
receptor and enzyme on the same protein
G- protein coupled ion channles are...
- slow ligand gated channes
- receptor and channel have different proteins
Second messenger is also known as
- Intracellular messenger
- the G protein activates the amplifier enzyme which amplifies second messenger production
Steps in cAMP second messenger system
- 1st msngr binding activates the g protein
- Ga subunit will then activate adenylate cyclase
- Adenylate cyclase convert ATP to cAMP 2nd msnger
- cAMP activates protein kinase A
- Protein kinase A transfer a phosphate group from ATP to a target protein
- Phosphorylated protein will have an altered activity
How does termination of Second messenger system occur
cAMP is degraged by cAMP phosphodiesterase
What enzyme speeds up cAMP amplification?
What is the advantage of having 2nd messenger?
- Signal amplification
- each step recruits more participants
- small amounts of ligand can trigger a huge response