Name the principle biochemical components of the cell membrane?
Phospholipid and protein molecules
what is the actual width of the cell membrane?
7-8nm
What Is the main function of the cell membrane?
To aid transport of certain substances into/out of cells
Name the 4 structural components of the cell membrane
-Phospholipids
-Proteins
-Carbohydrates
-Cholesterol
How are the phospholipid molecules arranged?
They are arranged as a bilayer with one sheet of phospholipid molecules opposite another
What do phospholipids form?
Bilayers with hydrophilic heads pointing outwards , interacting with the tissue fluid/blood plasma that surrounds the cell and the cytoplasm inside the cell. The hydrophobic tails of both layers point towards the inside of the membrane
Explain why the hydrophilic heads point outwards and the hydrophobic tails point inwards
Because the tails repel water in the cytoplasm and extracellular fluid whereas the heads are attracted to this fluid
Which type of proteins are in the membrane?
Globular proteins
Where in the membrane are proteins found?
Extrinsic proteins can be found on the surface or partly embedded
Intrinsic proteins can be found extending completely across both phospholipid layers
Describe and explain the position of the charged and uncharged parts of the protein molecule
Charged groups are positioned outside because they’re attracted to the polar molecules such as water and the hydrophilic heads.
Uncharged groups are positioned inside because they interact with non-polar molecules such as the hydrophobic tails
Where are carbohydrates found?
They are found only pointing outside of the cell attached to either proteins (glycoproteins) or the phospholipids (glycolipids)
How are these carbohydrates formed?
They are formed through glycosylation
What are the carbohydrate chains collectively known as?
The glycocalyx
Where is cholesterol found?
Between the phospholipids
What is the function of cholesterol?
Controls membrane fluidity
Why is the model called the fluid mosaic model?
Fluid- The individual phospholipid molecules can move around relative to one another
Mosaic- The proteins embedded in the bilayer vary in size and shape and are arranged in a random pattern
What is the function of intrinsic proteins?
Acts as carrier or channels to allow the passage of charged or polar molecules such as glucose
What is the function of extrinsic proteins?
Associated with one layer only
May act as receptors for hormones
What is the function of glycocalyx?
Act as cell to cell recognition
Also important in cell adhesion and acting as receptors
