Flashcards in DIFFUSION Deck (32)
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1
Is diffusion active or passive
passive
2
What is passive transport
exchange of substances that do not require metabolic energy
3
What is active transport
exchange of substances that require metabolic energy
4
Where does passive transport get their energy from
the natural, in-built motion of particles
5
Are all particles constantly in motion and why
yes because of the kinetic energy that they possess
6
What type of motion do the particles move in
random
7
What is diffusion
the net movement of molecules or ions from a region where they are more highly concentrated to one where their concentration is lower until evenly distributed
8
Why can oxygen and carbon dioxide diffuse through simple diffusion
they are small so can pass through spaces between the phospholipids, and non-polar so they are soluble in lipids which means they can dissolve in the hydrophobic bilayer
9
What is simple diffusion
when molecules diffuse directly through a cell membrane
10
What is facilitated diffusion
the movement of charged ions and polar molecules with the help of carrier and protein channels
11
Where does facilitated diffusion get its energy from
the in-built motion (kinetic energy) of the diffusing molecules
12
What are the 2 types of protein involved in facilitated diffusion
ptorain channels and carrier proteins
13
What do protein channels form
water-filled hydrophilic channels across the membrane
14
What do protein channels allow
specific water-soluble ions to pass through the membrane
15
When do protein channels open
in the presence of specific ions
16
How do protein channels open and close
the ion binds to the protein causing it to change shape in a way that one side opens and the other closes
17
What do protein channels control
which ions enter and exit
18
What energy do carrier proteins use
the kinetic energy of the molecules
19
What do carrier proteins do
transport large molecules across the membrane down their concentration gradient
20
How do carrier proteins work
the large molecule binds to the carrier protein in the membrane at the binding site which causes the protein to change shape, and therefore releases the molecule the other side of the membrane
21
What does the rate of simple diffusion depend on (3 points)
1) concentration gradient
2) thickness of the exchange surface
3) surface area to volume ratio
22
How does concentration gradient affect simple diffusion
higher conc gradient = faster rate of diffusion
23
What is reached as simple diffusion continues
an equilibrium
24
Why happens to the rate of simple diffusion as it continues
it slows down
25
How does surface thickness affect simple diffusion
thinner = shorter diffusion distance = faste rate of diffusion
26
How does SA:V ratio affect simple diffusion
larger the SA:V ratio = faster diffusion rate
27
What is an example of an increased surface area
microvilli in epithelial cells in the small intestine
28
What does the rate of facilitated diffusion depend on (2 points)
1) concentration gradient
2) number of protein channels / carrier proteins
29
How does concentration affect facilitated diffusion
higher conc gradient = faster rate, up to a point (equilibrium reached)
30
