W4L2 - Nutrient and Ion Transport Flashcards
What is facilitated diffusion
no energy required and moves down a concentration gradient (high to low)
What are gated channels
Mechanically gated channels that open and close to a stimulus
What are carrier channels
bind to molecule, change shape and move across membrane, very specific
What are transporters
accelerate the movement of small
and large molecules across membranes
What are proton pumps
transport protons → use ATP to move protons
What is co-transport and how does it work
H+ travels through proton pump > produces energy > using that energy H+ travels back through the co-transport and another molecule also gets dragged along with it.
What is a membrane potential
voltage differences across membrane
How does a sodium-potassium pump work?
NIL
What charge is the cytoplasm compared to the extracellular fluid
negatively charged
What are the diffusion of ions affected by
electrical force (charge gradient) and chemical force (conc gradient)
Where do small molecules and H2O leave through
Small molecules such as O2 can pass directly through the lipid bilayer, whilst water and other small molecules need transport proteins to pass through
How do larger molecules (polysaccharides and proteins) cross the membrane
Vesicles
What is endocytosis
portions of plasma membrane forming vesicles
What is exocytosis
Vesicles fuse with the plasma membrane to export the content by three secretory pathways
What are the three different types of endocytosis
pinocytosis, phagocytosis, receptor mediated endocytosis
What are the three types of secretory pathways in exocytosis
constitutive, regulated, lysosomal regulated pathways
What is pinocytosis
vesicles formed → all solutes taken into cells no specifity
What is phagocytosis
engulf cell and package into large vesicle → used by macrophages
What is receptor mediated
recognise proteins and bind to specific molecules
Where are receptors clustered in
clustered in regions called coated pits
Where do the vesicles form in receptor mediated
formed where the receptors and bound molecules are concentrated
What is a constitutive secretory pathway
continuous release of materials w/o external signals
What is a regulated secretory pathway
triggered by specific signals to release stored substances
What is lysosomal secretory pathway
lysosomes fuse with plasma membrane → release waste/repair damage
What is passive transport
movement of substances without energy > conc gradient (high to low)
What is active transport
movement of substances against conc gradient > requires energy
What is vesicular transport
movement via vesicles
What energy do proton pumps require?
ATP
What is secondary active transport
A proton pump > ATP > ion gradient > potential energy.
A cotransporter uses that energy to move H+ and another molecule with it
What are lysosomes
Membrane bound organelles that contain digestive enzymes
