Solute: substances that are dissolved in fluid (eg. salt)

Solvent: the liquid the solute is dissolved in (eg. water)

Passive Transport

movement of materials across a cell membrane without energy; Movement along a concentration gradient

Diffusion

  • movement of particles from an area of high concentration to an area of low concentration
  • movement will continue until equilibrium is achieved

Example: – Perfume

– CO2 and O2 exchange in lungs

Osmosis

  • diffusion of water through a selectively permeable membrane (eg. cell membrane)
  • Water moves from higher concentration to lower concentration.

Hypertonic – the concentration of solutes outside the cell is higher than inside the cell.

  • water moves out.

Isotonic – the concentration of solutes outside the cell is the same as inside the cell.

  • equilibrium

Hypotonic – the concentration of solutes inside the cell is higher than outside the cell.

  • water moves in.
  • this is important to aquatic organisms
  • Your kidney uses osmosis to regulate water balance in the blood. This determines the amount of water in urine.

Facilitated Diffusion

  • Molecules too large for simple diffusion use protein carriers in the cell membrane to assist them. They pass through a protein, that acts like a channel in the membrane.
  • Substances still move across a concentration gradient. No energy is used!!!!
READ:
Diffusion, Osmosis, and Movement Across a Membrane

Example

  • Glucose is too large to diffuse through the membrane
  • It uses the protein carriers to enter the cell – glucose is constantly being used up in a cell so there is a lower concentration inside the cell.

Active Transport – Using energy to move materials across the cell membrane; materials usually move against the concentration gradient

Sodium/Potassium Pump
  • Located in nerve cells and critical to their function
  • Nerve cells must maintain a higher concentration of Na+ outside the cell and K+ inside the cell.
  • Special transport proteins in the membrane pump Na+ out of the cell and K+ into the cell. This takes energy

Endocytosis

  • moving materials into the cell by pinching the cell membrane
  • this forms a vesicle inside the cell
  • molecules too large to pass through the cell membrane

Phagocytosis “cell eating”movement of large molecules

Example: how white blood cells “eat” bacteria

Pinocytosis “cell drinking” – transport of liquids into the cell

Exocytosis
  • Exporting large molecules outside the cell
  • A vesicle inside the cell fuses with the cell membrane and then releases it’s contents outside the cell.
READ:
Effect of Salt Concentration on Osmosis in Potato Cells Lab Answers

Example: – how insulin is moved out of the pancreas into the blood

Cite this article as: William Anderson (Schoolworkhelper Editorial Team), "Cell Transport: Passive & Active," in SchoolWorkHelper, 2019, https://schoolworkhelper.net/cell-transport-passive-active/.

Help Us Fix his Smile with Your Old Essays, It Takes Seconds!

-We are looking for previous essays, labs and assignments that you aced!

-We will review and post them on our website.
-Ad revenue is used to support children in developing nations.
-We help pay for cleft palate repair surgeries through Operation Smile and Smile Train.

guest
0 Comments
Inline Feedbacks
View all comments