forces across membranes 2

Question 1

methods of transport across a membrane

Answer 1

endocytosis and exocytosis: transport of macromolecules. across the membrane
diffusion; process by which a gas or substance moves from an area of high concentration to low concentration to fill all the volume available
carrier-mediated transport: movement through proteins either by facilitated diffusion( if down concentration gradient) or by active transport( if against concentration gradient)

Question 2

how does end-exo cytosis work?

Answer 2

endo-membranes fold inwards to form a vesicle which engulfs the macromolecule and brings it into the cell where further reactions will take place

Question 3

how does diffusion work?

Answer 3

molecules will move from an area of high concentration to an area of low concentration in order to fill up the entire volume.

Question 4

what does diffusion through the bilayer depend on?

Answer 4

1-size (small)
2-charge (uncharged)
3-lipophilic
1+2 more important than 3
gases and small nutrients can diffuse across.

Question 5

how do ions move across the membrane

Answer 5

through ligand or voltage gated channels either by facilitated diffusion or by active transport.

Question 6

what is the membrane potential ?

Answer 6

the difference in charge which is established on both sides of the membrane due to different concentration of ions.

Question 7

electrochemical gradient

Answer 7

the gradient which forms as a result of the difference in charge and concentration on both sides of the membrane.