Bio Unit 1 Test- Communication
Cystic Fibrosis definition
is a genetic disease caused by a defective gene (CFTR gene)
CFTR gene deffinition
is a gene that instructs for making a protein that functions as a channel across the membrane of cells that produce mucus, sweat, saliva, tears, and digestive enzymes.
more info on CFTR
- This channel transports negatively charged chloride ions into and out of cells
- The chloride protein also regulates the function of other channels such as those that transport positively charged particles called sodium ions across cell membranes. These channels are necessary for the normal functioning of organs such as the lungs and pancreas.
- All of these changes prevent the channel from functioning properly, which impairs the transport of chloride ions and water into and out of cells. As a result, cells that line the passageways of the lungs, pancreas, and other organs produce mucus that is abnormally thick and sticky.
Passive transport
Diffusion:
the movement of particles from an area of ↑ concentration (↑ [ ]) to an area of ↓ concentration (↓ [ ]) which does not require ATP.
Passive transport
- The plasma membrane will allow certain substances to cross it but not others. Such a membrane is referred to as selectively permeable.
The three characteristics of a molecule that determine its permeability are;
1. Polarity (hydrophobic vs hydrophilic)
2. Charge
3. Size
Active transport
substances are moved across a membrane against the concentration gradient (from a low concentration to a high concentration) this is a mediated by a membrane carrier molecule.
active transports
Pumps
Through the use of channels (proteins) and carrier proteins that are embedded in the cell membrane these substances can be transported into the cell.
active transport
Vesicles
Receptor mediated endocytosis is a process by which cells absorb molecules (endocytosis) by the inward budding of plasma membrane vesicles containing proteins with receptor sites specific to the molecules being absorbed.