Fluid Mosaic Model
What does the “fluid” part of the fluid mosaic model refer to?
The ability of lipids and proteins to move sideways within the membrane.
What does amphipathic mean?
Having both hydrophobic and hydrophilic regions.
What is passive transport?
Movement of molecules across the membrane without energy input.
What is osmosis?
Diffusion of water through a selectively permeable membrane from high concentration of water (low solute) to low concentration of water (high solute).
What is endocytosis?
Process by which a cell takes in large molecules by engulfing them.
Which molecule stabilizes the membrane at different temperatures?
Cholesterol.
What part of a phospholipid is hydrophilic?
The phosphate head.
What drives diffusion?
The movement of molecules from high to low concentration (concentration gradient).
In a hypotonic solution, what happens to an animal cell?
It swells and may burst.
What is exocytosis?
Process by which a cell expels materials using vesicles.
What are the four main components of the plasma membrane?
Phospholipids, proteins, cholesterol, and carbohydrates.
What are the two types of membrane proteins?
Integral (or transmembrane) and peripheral proteins.
What is active transport?
Movement of molecules against the concentration gradient using ATP.
What happens to a plant cell in a hypertonic solution?
It loses water and undergoes plasmolysis.
What is the difference between phagocytosis and pinocytosis?
Phagocytosis takes in solids; pinocytosis takes in liquids.
Why is the plasma membrane described as a “mosaic”?
Because it is made up of various molecules like proteins and lipids arranged in a pattern.
How do carbohydrates help in cell-cell recognition?
They form glycoproteins and glycolipids that act as ID tags on the cell surface.
What type of macromolecules assist in facilitated diffusion?
Proteins (Transport or channel proteins)
What term describes a plant cell firm with water pressure?
Turgid.
What role do receptors play in receptor-mediated endocytosis?
They specifically bind and bring in target molecules.
How do unsaturated fatty acids affect membrane fluidity?
They increase fluidity by preventing tight packing due to kinks in their tails.
Why can viruses like HIV infect only specific cells?
Because their proteins bind to specific receptor sites on the host cell membrane.
What are the three types of endocytosis?
Phagocytosis, Pinocytosis, and Receptor-mediated endocytosis.
How does a Paramecium avoid bursting in freshwater?
It uses a contractile vacuole to pump out excess water (osmoregulation).
Why does bulk transport require energy?
Because it involves moving large materials and changing the membrane’s shape (vesicle formation).