April 20, 2020
- Use the fluid mosaic model to explain the properties and functions of cell membrane.
- Appreciate the uses and limitations of scientific models.
Fluid mosaic model
👆🏻 This is the fluid mosaic model that used to illustrate the structure of cell membrane.
In HKDSE Biology examination, the structure of fluid mosaic model will be asked to be drawn (SIMPLE VERSION) ❗️ ❕
Why named as fluid mosaic model ❓ ❔
- Fluid - hydrophobic components of cell membrane (lipid, membrane protein) can be able to move laterally as well as the sideways within the cell membrane. The fluidity of cell membrane is indicated.
- Mosaic - integral protein, peripheral protein, glycoprotein, glycolipid and cholesterol are embedded in the phospholipid bilayer. The complex composition of cell membrane is indicated.
🔸 Properties of cell membrane
👆🏻 This is the structure of phospholipid which is the main component in cell membrane.
- Cell membrane is made up by phospholipid that it consist of a water loving head (phosphate and glycerol) and a water hating tail (fatty acid).
- Phospholipid will self-assemble into a phospholipid bilayer that polar head contact with the aqueous medium while non-polar tail shielded from aqueous medium.
- Cell membrane is amphipathic which means it is both non-polar (hydrophobic)as well as polar (hydrophilic) in the nature.
🔹 Functions of cell membrane
- The permeability of cell membrane is controlled by the phospholipid bilayer. Cell membrane is permeable to small hydrophobic molecules since they can pass through the interior hydrophobic layer made up of water hating tail - fatty acid.Yet, cell membrane is impermeable to small hydrophilic molecules since hey cannot pass through the interior hydrophobic layer made up of water hating tail - fatty acid.
- Integral protein (embedded through the phospholipid bilayer) and peripherial protein (embedded half-way the phospholipid bilayer) allows the transport of specific material into or out of the cell.
- The fluidity of cell membrane is permitted by movable phospholipid. The fluidity of cell memebrane is important that the cell can carry out intercellular communication, intracellular communication as well as membrane-bound enzyme activity.
In HKDSE Biology examination, we have to understand the use of fluid mosaic model to explain the properties and functions of cell membrane. Even though, there are still limitation on fluid mosaic model ❗️ ❕
That's the end of this topic 👏🏻
References
- Thomas, B. & Chris, H. (2013)Hong Kong DSE Biology Critical Guide. Yellowreef Limited.
- Libretexts. (2019, November 19). 5.1B: Fluid Mosaic Model. Retrieved from https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book:_General_Biology_(Boundless)/5:_Structure_and_Function_of_Plasma_Membranes/5.1:_Components_and_Structure/5.1B:_Fluid_Mosaic_Model
- Boundless. (n.d.). Boundless Anatomy and Physiology. Retrieved from https://courses.lumenlearning.com/boundless-ap/chapter/cell-membranes-and-the-fluid-mosaic-model/