Unit III Flashcards
What are the functions of cell membrane
Controls what enters and exits the cell to maintain an internal balance
Provides protection and support for the cell
The internal balance inside the cell that cell membrane maintains is called
Homeostasis
Some membrane contains proteins called
Membrane proteins
The phosphate head of the cell membrane is ________, and the fatty acid tails is __________.
Polar, non-polar
Allows a molecules in and keeps other molecules out
Selectively permeable
In 1972 they proposed that the membrane is a mosaic of proteins dispersed within the bilayer with only the hydrophilic regions exposed to water.
S.J Singer and G. Nicolson
70% of cell membrane proteins part and parcel of membrane structure
Integral proteins
Lei transfer substances against concentration/ electrical gradient
Pumps
Opened and closed by gates
Channel proteins
It involved in transport of substances
Carrier proteins
It takes place in membrane reaction
Enzyme proteins
They bear appropriate sites for recognition of specific ligands
Receptor proteins
They are bound to the surface of the membrane
Peripheral proteins
Other functions of cell membrane
Transport
Enzymatic activity
Signal transduction
Cell to cell recognition
Intercellular joining
Attachment to the cytoskeleton and extracellular matrix (ECM)
Carbohydrates covalently bonded to lipids
Glycolipids
Membrane carbohydrates covalently bonded to proteins
Glycoproteins
__________ molecules such as hydrocarbons can dissolve in the lipid bilayer and passed through the membrane rapidly
Hydrophobic or nonpolar molecules
__________ molecule such as sugars do not cross the membrane easily
Polar molecules
It allows passage of hydrophilic substances across the membrane
Transport proteins
Transport proteins that have hydrophilic channel that certain molecules or ions can use as a tunnel
Channel protein
Channel proteins that facilitate the passage of water
Aquaporins
Transport proteins that bind to molecules and change shape to shuttle them across the membrane
Carrier proteins