1.2 Flashcards
What is the plasma membrane?
A boundary that defines the space of the cell, separating its internal contents from the surrounding environment.
Define homeostasis.
The active maintenance of a stable environment within cells and organisms.
What does selectively permeable mean?
Allows certain molecules to pass while blocking others.
What is passive transport?
When molecules move across the cell through diffusion.
What is a channel in the context of membrane transport?
A type of membrane transporter that provides an opening between the inside and outside of the cell.
What are gated channels?
Membrane channels that only open in response to some signal that may be chemical or electrical.
Define carrier diffusion.
Molecules move directly through the lipid layer.
What is facilitated diffusion?
Molecules move through a membrane transporter.
What are aquaporins?
Channel proteins that allow water to move through the cell membrane.
What is osmosis?
The movement of water across a selectively permeable membrane.
What is active transport?
The uphill movement of water against the concentration gradient.
What is primary active transport?
Active transport that directly uses ATP.
What is secondary active transport?
Active transport that uses the energy of a chemical gradient for the movement of molecules.
Define electrochemical gradient.
A gradient that has both chemical and electrical components.
What are contractile vacuoles?
Organelles that help regulate water balance in some cells.
