B2.1 Membranes and membrane transport Flashcards
What is the definition of the plasma membrane?
The plasma membrane surrounds the cell and controls the movement of substances in and out.
What are the main components of the plasma membrane?
Phospholipid bilayer, integral proteins, peripheral proteins, cholesterol, glycoproteins
What is the phospholipid bilayer?
Two layers of phospholipids with hydrophilic heads (water attracting) and hydrophobic tails (water repelling)
What are the integral proteins?
Embedded in the membrane, help with transport
What are the peripheral proteins?
Attached to the surface, used for signaling and structure.
What is cholesterol?
Maintains membrane fluidity and stability (only in animal cells)
What are glycoproteins?
Proteins with carbohydrate chains, used in cell recognition
What are the three types of membrane transport?
Passive transport, active transport, bulk transport
Which of these requires energy: Passive transport, active transport, bulk transport?
Active transport and bulk transport
What are the three types of passive transport?
Diffusion, facilitated diffusion, osmosis
What is diffusion?
Movement of molecules from a high to low concentration
What is facilitated diffusion?
Uses channel or carrier proteins to help large or charged molecules cross the membrane.
What is osmosis?
Movement of water from high to low concentration through a partially permeable membrane.
What is active transport?
Movement of substances against the concentration gradient (low to high concentration) using protein pumps.
What is an example of active transport?
Sodium-potassium pump in nerve cells.
What is endocytosis in bulk transport?
Cells engulfing substances into a vesicle.
What is an example of endocytosis in bulk transport?
White blood cells engulfing bacteria.
What is exocytosis in bulk transport?
Cell expels substances via vesicles hormone secretion.
