smthg Flashcards
Molecules move across the membrane with the help of specific transport
proteins (channel proteins or carrier proteins).
B. Facilitated Diffusion
Provide a hydrophilic pathway for specific molecules or ions
to pass through the membrane.
Channel Proteins:
Bind to specific molecules on one side of the membrane,
change shape, and transport them to the other side.
Carrier Proteins:
The diffusion of water across a selectively permeable membrane, from a
region of low solute concentration (high water potential) to a region of high solute
concentration (low water potential)
C. Osmosis
Direct use of ATP to power the
movement of molecules across the membrane via
transport proteins.
A. Primary Active Transport
This pump
moves 3 sodium ions (Na⁺) out of
the cell and 2 potassium ions (K⁺)
into the cell against their respective concentration gradients.
Sodium-Potassium Pump (Na⁺/K⁺ ATPase):
Both
molecules move in the same
direction across the
membrane.
Symport (Cotransport):
Uses the energy from
the electrochemical gradient created
by primary active transport (rather
than directly using ATP) to move other
molecules against their concentration
gradient.
B. Secondary Active Transport (Cotransport)
The molecules move in opposite directions
Antiport (Countertransport):
The cell membrane engulfs external materials, forming a vesicle that brings
them into the cell.
Endocytosis
The cell engulfs large particles or
microorganisms.
o Phagocytosis (“Cell Eating”):
The cell takes in extracellular fluid containing
dissolved substances.
Pinocytosis (“Cell Drinking”):
Specific molecules bind to receptors on the
cell surface, triggering vesicle formation.
Receptor-Mediated Endocytosis:
Vesicles containing substances fuse
with the cell membrane, releasing their contents
outside the cell.
Exocytosis
