Eukaryotic Cell: Plasma Membrane Flashcards
What are the basic components of the plasma membrane?
Lipids (phospholipids)
Proteins
What is the fluid mosaic model?
Protein rafts floating in a sea of lipids
What are the basic functions of membrane proteins?
transport
enzymatic activity
signal transduction
cell-cell recognition
attachment (intracellular & ECM)
What is passive transport?
Diffusion of a substance down a gradient and across the plasma membrane
What is osmosis?
Diffusion of water across a permeable membrane
What is an isotonic solution?
When the concentration of solute is the same on both sides of a membrane
What is a hypertonic solution?
When the solution has higher concentration of solute than the cell.
What happens to a cell in a hypertonic solution?
The cell loses water to the solution (shrinks)
What is a hypotonic solution?
The concentration of solute is less than the inside of the cell.
What happens to a cell in a hypotonic solution?
Water flows into the cell and it gets lysed (bursts)
What is active transport?
A protein pump moves a solute across the membrane against a concentration gradient
This requires energy
What are the structure and function of membrane channels?
Transmembrane channel proteins (basically corridors) allow solutes (usually ions) to move down a concentration gradients
What are gated channels?
A type of transmembrane protein that open/close in response to stimuli (eg electrical or chemical)
Describe the structure & function of the Na-K pump
This is a form of active transport
Goal is to increase K- inside cell
Requires ATP
Na concentration is high outside of cell
K is high inside of cell
3 Na go OUT
2 K go IN
Result is a negative cell potential
What is cotransport?
It is a form of active transport
One solute moves down a gradient
It’s movement allows a second solute to move UP a gradient (in the same direction as the first solute)
What is exocytosis?
Transport vesicles inside cell
fuse with plasma membrane
Contents of vesicle spill OUT of cell
What is endocytosis?
Movement of molecules/matter from OUTSIDE to INSIDE the cell
What are the 3 main forms of endocytosis?
Phagocytosis (eating)
Pinocytosis (drinking)
Receptor-mediate endocytosis
What are the main types of cell signaling pathways?
Contact signaling (physical)
Chemical signaling
Electrical signaling
What are the stages of cell signaling?
Reception (signal molecule is detected)
Transduction (binding of signal converted to relay molecules inside of cell)
Response (intracellular activity)
What is paracrine signaling?
LOCAL signaling (between nearby cells)
What is endocrine signaling?
LONG-DISTANCE signaling
e.g hormones
What is the resting potential of a typical cell?
Negative due to Na-K pumps
What is a protein kinase?
An enzyme that transfers P from ATP to a protein
Can be part of a phosphorylation cascade
which is transduction
