B1.2.3 Cell Membrane Structure and Function Flashcards
All membranes around and within cells (including those surrounding organelles) are called…
plasma membranes
What do we call the plasma membrane that surrounds cells?
Cell-surface membrane
What is the function of a cell surface membrane?
- To separate the internal and external environments of the cell.
- To control the movement of substances in and out of the cell.
Name the components of a cell surface membrane.
- Phospholipids
- Proteins (intrinsic and extrinsic)
- Glycoproteins
- Glycolipids
- Cholesterol
Phospholipids have polar and non-polar regions. A molecules that exhibits both of these properties is said to be…
Amphipathic
What is a polar molecule?
A molecule that does not have an even distriibution of electrons making some regions more negative than others.
What is a non-polar molecule?
A moelucle that has an even distribution of electrons, meaning it does not have areas that are more negative than other areas.
Phospholipids are made form which 3 molecules?
Phosphate
Glycerol
Fatty acid ‘tails’ x 2
Describe the phosphate head of a phospholipid.
- Polar
- Hydrophillic - water loving
Describe the fatty acid ‘tails’ of a phospholipid.
- Non-polar
- Hydrophobic - ‘water hating’
What are the functions of the phospholipids in the cell membrane?
- Allow lipid-soluble (non-polar) substances to enter/exit the cell.
- Prevent water soluble (polar) substances entering/exiting the cell.
- Makes the membrane flexible and self-sealing.
Proteins in a cell membrane can either be __________ or _________.
Intrinsic or extrinsic
Which components of the cell-surface membrane are visible in this diagram?
Phospholipid bilayer
Cholesterol molecule (green)
Which components of the cell-surface membrane are visible in this diagram?
Phospholipid bilayer
2 x extrinsic proteins (carriers)
Which components of the cell-surface membrane are visible in this diagram?
Phospholipid bilayer
Glycolipid molecules x 2