types of passive transport (unit 2) ib bio

transport that has no energy required

passive transport

transport that energy is required

active transport

what type of transport is diffusion

passive

what is the rule of diffusion?

in the absence of other forces a substance will move from where there is a high concentration gradient to where there is a low concentration gradient

is diffusion slow or fast?

slow

how does diffusion occur without energy?

molecules have thermal (kinetic) energy and all molecules move into open spaces both randomly and directionally

in diffusion, substances move _______

down their concentration gradient

how is the concentration gradient involved in diffusion?

it is slow, it drives diffusion, and is spontaneous (no energy used)

how can the rate at which diffusion happens be changed?

by the permeability of the membrane

concentration difference

temperature

osmosis

still diffusion, but specific to water’s movement from a high to low concentration of water across a membrane

same molar concentration in 2 solutions

isotonic

what if the membrane is not permeable to the solute?

if the solutes cannot move then the water will, it moves through channel proteins called aquaporins

what is an aquaporin?

water holes

hypertonic solutions

solution with more concentration of solutes, less water

hypotonic solutions

solution with less concentration of solutes, more water

where does water move in a hypertonic solution?

net movement of water out of the cell

where does water move in a hypotonic solution?

net movement of water into the cell

in osmosis, water goes from _______ to ______, and the solute concentration goes from ______ to _________

is water potential higher in hypotonic or hypertonic solution?

its higher in a hypotonic solution

what does psi (Ψ) represent?

water potential

water potential equation

Ψs +Ψp = Ψ

what does Ψs represent and measured in?

solute potential → -iCRT

What does Ψp represent?

pressure potential

when a solution is hypertonic to an animal cell, what happens?

the cell loses water, shrivels/shrinks, then dies

when a solution is hypotonic to an animal cell, what happens?

the cell gains water, and bursts/ goes through lyses

when a solution is isotonic to an animal cell, what happens?

there is no net movement of water, this is the ideal situation a cell wants to be in

when a solution is hypertonic to a plant cell, what happens?

it goes through plasmolysis (loses water) and shrinks

what is plasmolysis

plant cells lose water in a hypertonic solution, causing the protoplasm (the cell's inner contents) to shrink and pull away from the cell wall

when a solution is hypotonic to a plant cell, what happens?

the cell becomes turgid, because the cell wall exerts turgor pressure ( positive Ψp) this is the ideal situation for a plant cell to be in

what does it mean for a plant cell to be turgid?

swollen and firm due to being filled with water

when a solution is isotonic to a plant cell, what happens?

the cell becomes flaccid (limp) and the plant wilts

what is facilitated diffusion

quicker than normal diffusion, made for polar molecules

still goes from high to low concentration

what is facilitated diffusion facilitated by?

transmembrane proteins (either channel proteins or carrier proteins but most likely channel)

what are channel proteins?

provide a hydrophilic passage for polar molecules to slide through, they can be gated

How does a carrier protein work?

molecule to be transported binds to the carrier→ the carrier changes shape, pulling the molecule through (can also be used for active transport)

how are transport proteins similar to enzymes?

1. they can be saturated  → maximum rate of transport

2. they are specific for a molecule

3. they can become inhibited → meaning shape change could alter function