Exam 1 Lec 3 Membrane Flashcards
Where water is found?
- Blood
- Cytosol
- Interstitial fluid
66% of water in our body can be founded in:
Cytosol
The content of interstitial fluid is going to determine _____________________.
what is permeable to the site
Environment of the interstitial fluid: (6)
- Concentration of salt, and other electrolytes
- Concentration of energy-riched molecules
- Concentration of oxygen and carbon dioxide
- Concentration of waste product
- pH
- Temperature
Cells vary in ______ and _______.
shape; function
Two types of membrane proteins: _________ and _________. They function in ________, __________, and ________ _________.
peripheral; integral; junctions; transport; chemical signaling
Cell-to-cell junctions: (3)
- Desmosomes
- Tight junctions
- Gap junctions
Desmosomes
Provide rigidity for neighboring, resist a lot of pulling and pushing, make sure neighboring cells are anchored together
Tight junctions; name the type of protein that is specific for gap junctions
Push cells very close to each other to minimize the interstitial space in between them to prevent paracellular pathways; in parts of body where lots of movement occur; to ensure permeability is through the cells, but not between the cells
*Occludin
Have a very high control over ___________ pathway; whereas cannot control over ___________ pathway, like leaking
transcellular; paracellular
Gap junctions; name the type of protein that is specific for gap junctions
Openings between neighboring cells; facilitates exchanges between neighboring cells; promotes synchronized moves
*Connexon (6 subunits of connexin)
Where can we find
a) demosomes
b) tight junctions
c) gap junctions
a) skin/muscle
b) digestive system/urinary system
c) heart/lungs/brain
Diffusion can occur through _______________, and _______________.
lipid bilayer; ion channels for specific ions
The ______ lipid-soluble the molecule, the _____ rapidly it diffuses
more; more
How does water move across the membrane?
- Through lipid bilayer
- Through aquaporins
Osmosis is passive or active transport; water diffuse from _____ concentration of solute to ______ concentration of solute
Passive; high; low
Types of solution that direct water movement:
Isotonic, hypertonic (water out; cell shrink), and hypotonic (water in; cell burst)
Polar and charged substances do not diffuse across the lipid portion of the lipid. (T/F)
T
List 4 gating mechanisms for the channels:
- Voltage gated
- Stretched gated
- Phosphorylation gated
- Ligand gated
Voltage-gated channel
By charge:
- extracellular positive, cytoplasm negative -> close
- extracellular negative, cytoplasm positive -> open
*brain cells
Stretch gated channel
By stretching:
- loosen -> close
- tighten -> open
*skin cells, hair cells in the ear
Phosphorylation gated channel
ATP/ phosphate in the cytoplasm -> open
without -> close
*nervous system cells; muscles
Ligand gated channel
lock and key, aka receptor gated channel
*nervous system cells; muscles
Voltage-, ligand-, stretch-, and phosphorylation-gated channels are all by ________ diffusion.
simple
Passive transport, aka ___________ transport, are ______________ proteins of quaternary structure creating a pore for substance pathway. Also included _______ _______.
channel; transmembrane; carrier proteins
Channel transport requires input of energy. (T/F)
F; channel transport is another name for passive transport
_________ transport is highly specific. It is used to transport larger molecules, or against the concentration gradient. It is ______ than ion channels.
Mediated; slower
2 types of mediated transports:
- Active transport (needs energy)
- Facilitated diffusion (does not need energy)
Facilitated diffusion
From high to low concentration; does not require energy; can become saturated
Ion channels are facilitated diffusion. (T/F)
F
In active transport (2):
- Requires energy
- Against concentration gradient
Active transport has three types of transporters:
- Uniport transporters (1 solute, 1-way)
- Symport transporters (2 solutes, 1-way) (Na+/Glu)
- Antiport transporters (2 solutes, 2-way) (Na+/K+ pump)
2 types of active transport:
- Primary active transport
- Secondary active transport
Primary active transport:
Give an example
- Requires ATP
- Also known as pumps
- Only cations (Na+, K+, Ca2+, etc.) pass through
*Na+/K+ pump
Na+/K+ pump
3 Na+ out
2 K+ in
Why Na+/K+ pump called primary active transport?
Because it requires ATP to bind directly to the protein for it to work
Secondary active transport:
Give an example
- Does not require ATP
- Use chemical gradient of one ion to move another ion
*Na-glucose cotransporter
Na-glucose cotransporter
- Uses the energy of Na to move the glucose against its concentration gradient
- Na is along concentration gradient; glucose is agaisnt
- For this to occur, Na concentration must remain low at all times (this is done by the sodium-potassium pump)
2 types of endocytosis:
- Phagocytosis
- Pinocytosis
Endocytosis
Plasma membrane invaginates toward the cell interior while surrounding the materials to be transported
Exocytosis
Materials packaged in vesicles are secreted from the cell
How does G-protein cascade work? (8 steps)
- Messenger binds to the receptor and activates it
- Receptor activates G-protein (which is normally unactiviated when binding with GDP)
- G-protein binds to alpha subunit
- Alpha subunit translocates
- Alpha subunit G-protein activates adenelyl cyclase (AC)
- AC converts ATP to cAMP
- cAMP activates protein kinase A (PKA)
- PKA phosphorylates other proteins to generate cellular response
