Cell Membrane Flashcards
(27 cards)
the main structure of the plasma membrane is……..
The phospholipid bilayer
Integral proteins def
trans-membrane proteins (proteins that cross the entire membrane). They are firmly embedded in the lipid bilayer.
It has a hydrophilic interior, extending into the cytoplasm and out of the cell, and a hydrophilic exterior, interacting with the fatty acid tails of the membrane, mainly due to the nonpolar R groups of the amino acids.
Integral proteins Functions:
Transportation across the membrane - acts as a bridge
Ex: Na+ channel, K+ channel, sodium potassium pump.
peripheral proteins Functions:
Receptors - signal transduction, over a thousand different receptors receiving information.
MHC1- Major Histocompatibility Complex 1; the self ID of each cell.
Cellular joining- (anchoring) + Cellular support (attached to cytoskeleton)
G-Protein = secondary messenger
Peripheral proteins def
proteins attached to one side of the membrane (exterior or interior), not embedded in the lipid bilayer. Peripheral proteins are hydrophilically bound to the membrane, attached usually to a carbohydrate forming a glycoprotein.
blood types (A,B,AB,O) reflect variations of………
carbohydrates on the surface of red blood cells.
All membrane proteins are ………..- made in the ………., where ………is added to the 3D structure of the protein.
All membrane proteins are glycoproteins- made in the RER lumen, where sugar is added to the 3D structure of the protein.
Functions of cholesterol in cell membrane
provides the membrane with a “Liquid Crystal Configuration”-
Attaching to the phospholipid tails, it provides strength to the membrane as well as solid characteristics.
Fluid mosaic model characteristics
Asymmetry
Liquid crystal
Mosaic appearance
Diffusion def
the passage of molecules from an area of high concentration to an area of low concentration is called “down concentration gradient”.
The passing molecule must be very small and non-polar. This process doesn’t require energy (ATP).
Passive transport types
Diffusion and Facilitated diffusion
Facilitated diffusion def
a transmembrane protein /channel can open to allow passage according to the concentration gradients of polar molecules or ions such as Na+, Ca+, K+ .
Active transport types
Primary active transport and secondary active transport
Primary active transport def + ex
pumping molecules against concentration gradient using ATP directly.
Ex: Na+- K+ pump- sodium-potassium pump.
(2K+, 3Na+)
secondary active transport def + ex
pumping molecules against their concentration gradients, using concentration gradients established by the primary active transport. By doing so it indirectly uses the ATP of the primary active transport.
Ex: Sodium-glucose transport uses the concentration gradient of Na+, created by the active transport of the sodium-potassium pump, in order to insert glucose into the cell.
types of Transport classified by Direction
Uniport- one molecule in one direction.
Example Ca+ enters into the cytoplasm from SER storage.
Cotransport-
Symport- two molecules in one direction. Ex: sodium-glucose
Antiport- two molecules in opposite directions. Ex: sodium-potassium.
Exocytosis def
Cell export- exporting molecules out of the cell like a vesicle. The process elongates the cell membrane
Endocytosis def
Cell import- importing into the cell by using vesicles. In this process, the cell membrane shortens .
Endocytosis types
Pinocytosis(cell drinking) - adding H2O or liquids to the cytosol.
Phagocytosis (cell eating)- some white blood cells can consume bacteria/ viruses by creating internal vesicles.
types of cell junctions
Tight junctions, GAP junctions, Anchoring proteins
protein used in Tight junctions
occludin
protein used in GAP junctions
connexin
protein used in Anchoring junctions
desmosomes with the help of intermediate filaments.
adhesion proteins examples
desmoglein and desmocollin
