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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
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What are 5 types of transport?
- Simple diffusion
- Facilitated diffusion
- Diffusion through channels
- Primary active transport
- Secondary active transport
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What factors affect Simple Diffusion?
- Lipid solubility
- Concentration gradient
- Surface Area
- Particles with small size and regular shape
- Membranes with relatively thin wall
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What factors affect Facilitated Diffusion?
- Rate of transport of each carrier
- Number of carriers
- Concentration Gradient
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Function: Uses ATP directly for molecule transport (to push from low to high concentration)
Primary active transport
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Function: Uses electrochemical gradient for molecule transport
Secondary transport
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When 2 molecules are moving in the same direction in Secondary active transport, this is called
Symport
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When 2 molecules are moving in different direction in active transport this is called
Antiport
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Definition: Diffusion of water through a membrane, always passive, unaffected by electric charge on cells
Osmosis
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Definition: same concentration (no net water movement, cell will remain the same)
isotonic
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Definition: higher concentration (water gets out of cells, causing it to shrink)
Hypertonic
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Definition: Lower concentration (water gets in, causing the cell to swell or burst)
hypotonic
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Function: Molecules enter the cells by vesicle formation
Endosytosis
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Function: Molecules are packaged into secretory vesicles inside the cell and released into the extracellular fluid
Excocytosis
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Endocytosis + Exocytosis =
Transcytosis
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3 factors affecting the strength of response
- Messenger
- Receptor
- Affinity
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What happens in Upregulation?
Receptor # increases
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What happens in down-regulation?
Receptor # decreases
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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)
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Function: Receptors are found in the cytosol or nucleus
Binding of receptor will result in gene activation or deactivation
Intracellular-Mediated Response
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Signal transduction consist of
- Intracellular mediated response
- Membrane bound receptor mediated response
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Three type of membrane bound receptors
- Channel linked receptors
- Enzyme linked receptors
- G protein coupled receptors
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Function: ligand binding causes the ion channel to open or close
Channel linked receptors
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Function: Ligand binding activaties the enzyme which will trigger cell response
Enzyme-linked receptors
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Function:
Opening or closing of ion channels
Activating second messenger system
GPCR (G protein coupled receptors)
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Channel linked receptors are
- fast ligand-gated channels...
- receptors & channels are on the same protein
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Enzyme linked receptors have...
receptor and enzyme on the same protein
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G- protein coupled ion channles are...
- slow ligand gated channes
- receptor and channel have different proteins
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Second messenger is also known as
- Intracellular messenger
- the G protein activates the amplifier enzyme which amplifies second messenger production
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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
- Termination
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How does termination of Second messenger system occur
cAMP is degraged by cAMP phosphodiesterase
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What enzyme speeds up cAMP amplification?
adenylate cyclase
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What is the advantage of having 2nd messenger?
- Signal amplification
- each step recruits more participants
- small amounts of ligand can trigger a huge response
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