Membrane Transport Flashcards
Function of CAMs
Help cells stick to each other
Crucial components in maintaining tissue structure
Play important roles in the cell’s growth
Protein Pumps
The carrier has two sides, with one to recognize the substance to carry and one to release ATP to provide energy for the protein carriers
As a result, the protein molecule changes its shape so the target substance can be carried across the membrane
After that, the phosphate molecule is released from the protein molecule and combines with ADP to form ATP in the mitochondria
The protein then reverts back to its original shape
Glycolipid Protein Location and Function
Location: Phospholipids with carbohydrates attached, hydrophilic
Function: Cell recognition, identifies self and non-self cells, forms a layer with glycoprotein called glycocalyx which binds cells together and prevents the tissue from falling apart
Glycoprotein / Conjugated Protein Location and Function
Location: Peripheral proteins but with carbohydrates called oligosaccharides attached, hydrophilic
Function: Cell recognition, identifies self and non-self cells, forms a layer with glycolipid called glycocalyx which binds cells together and prevents the tissue from falling apart
Function of Phospholipids in Cell Membrane
Allow lipid-soluble and polar substances to enter and exit the cell
Prevents water-soluble substances from entering and exiting the cell, acts as a hydrophobic barrier
Allows membrane fluidity and stability
Cotransport
The coupled movement of substances across a cell membrane via a carrier protein
A combination of facilitated diffusion and active transport
Types of Active Transport
Protein Pumps
Exocytosis
Endocytosis
Cholesterol
An amphipathic molecule that is needed for membrane fluidity and stability
Disrupts the regular packing of the tails which increases flexibility as it prevents the tails from crystalizing and solidifying
Allows membranes to function at a wider range of temperatures
Components of Plasma Membrane
Phospholipid and Cholesterol
What Determines How Easily Substances can pass Membranes
Size: Smaller substances can enter easier
Polarity: Non-polar (hydrophobic) molecules can pass easier than polar (hydrophilic)
Exocytosis
The process by which macromolecules leave the cell
Vesicles from RER transport proteins to Golgi apparatus
These Vesicles undergo modification from the Golgi and get repackaged and sent into the plasma membrane
The vesicles carrying the protein fuse with the membrane expelling the content outside the cell
The membrane then goes back to its original state
Fluid Mosaic Model
FMM was first suggested to describe the arrangement of molecules in the plasma membrane
Fluid: Always changing shape and flexible
Mosaic: The pattern of the scattered proteins when seen from above
Model: No one knows how plasma membrane looks like, so this was constructed based off experiments on the behaviour of the membrane
Importance of Selective Permeability
Helps maintain and regulate a cell’s internal environment and conditions
Permeability depends on size, charge, and polarity of molecule
Active Transport Features
Substances move from low to high concentration
Substances move against concentration gradient
Requires ATP and a protein pump
Equilibrium is NOT reached
Examples include endocytosis, exocytosis, and active transport
Active Transport
The movement of substances through the membrane against their concentration gradient from low to high concentration through the use of ATP and carrier molecules