Chapter 5: 5.3 Flashcards
Diffusion (22 cards)
What is diffusion?
is the net or overall movements of particles (atoms, molecules or ions) from a region of low concentration to region of higher concentration.
- and it takes place until there is a concentration gradient between the two areas
What are two modes of transport/movement of substances between cells and their environment?
Passive movement
Active movement
What is the different between passive movement and active movement?
Passive movement = utilities the energy from natural particles rather than the energy of other sources.
Why does diffusion happen in a gas or liquids? How does particles diffuse?
this is because the particles have kinetic energy (are moving).
- particle movement is random and happens when equal distribution of particles eventually become unequally distributed.
What is simple diffusion?
is diffusion that happens in the absence of a membrane considered
What factors effect the rate of diffusion?
Temperature
Concentration difference
PH
How does temperature affect the rate of diffusion?
The higher the temperature the higher the rate of diffusion = This is because particles have more kinetic energy and move higher speeds
How does Concentration Gradient effect the rate of diffusion?
The greater the concentration difference between two regions the faster rate of diffusion…. this is because the overall movement from higher concentration to lower concentration
How does Concentration Gradient effect the rate of diffusion?
The greater the concentration difference between two regions the faster rate of diffusion…. this is because the overall movement from higher concentration to lower concentration
What is a concentration difference?
Is the concentration gradient which goes from low to high concentration - diffusion happens up it
What is facilitated diffusion?
Diffusion that happens across a membrane through channel
Why does phospholipid bilayers have channel proteins?
This is to allow on-polar molecules and ions to pass through
Why are membranes that contain protein channels selectively permeable?
This is because the protein channels are specific to a specific one molecules or ion
What factors effect the rate of facilitated diffusion?
- temperature
- concentration gradient
- membrane surface area
- thickness
- number of carrier protein present
What are the proteins that facilitated diffusion take place in (in the membrane)?
glycosidic proteins
True or false - facilitated diffusion does require external energy for it to take place
True or false - facilitated diffusion happens up a concentration gradient
False - facilitated diffusion does not require external energy and facilitated diffusion happens down a concentration gradient.
What factors effect the rate at which molecules and ions diffuse across the membrane? How?
surface area - the bigger the area of exchange the faster rate of diffusion
thickness of membrane - the thinner the exchange surface the faster the rate of diffusion
How does you calculate rate of diffusion?
Diffusion = distance
————-
time
or = volume
————-
time
How does partially permeable part of the membrane work? Why is considered it partially permeable?
- this is because the membrane has hydrophobic interior that repels substances with a positive or negative charge (ions) so they can’t pass through easily
- polar molecules such as water with partial positive and negative charge can diffuse through the membrane but at a slow rate. These can pass the membrane more easily than larger ones
How does partially permeable part of the membrane work? Why is it considered to be partially permeable?
- this is because the membrane has hydrophobic interior that repels substances with a positive or negative charge (ions) so they can’t pass through easily
- polar molecules such as water with partial positive and negative charge can diffuse through the membrane but at a slow rate. These can pass the membrane more easily than larger ones
{- Particles can only pass through the phospholipid bilayar if it is permeable to the particles
- Non-polar molecules such as oxygen diffuse through freely down a concentration gradient}
How is cells adapted for diffusion?
They are microscopic - smaller cells means faster rate of diffusion. As particles have shorter distance to travel.
Why is not a good idea for cell to be big when it comes to diffusion?
- As bigger cell will mean bigger rates of diffusion
- and reactions won’t get their substrates in required distance
