What is the Cell Surface Membrane made of?
The Cell Surface Membrane is made up of a phospholipid bilayer with hydrophilic heads and hydrophobic tails. It contains cholesterol, carrier proteins, channel proteins, glycoproteins, glycolipids, and receptors.
What is the function of cholesterol in the Cell Surface Membrane?
Cholesterol stabilizes the membrane structure.
What are carrier proteins and channel proteins used for?
They are used to transport substances across the membrane.
What is the role of glycoproteins and glycolipids?
They are involved in cell recognition and signaling.
How do proteins move in the Cell Surface Membrane?
Proteins move laterally in the membrane and are not fixed in one place.
What is passive transport?
Passive transport is the movement of molecules down their concentration gradient without the need for metabolic energy (ATP).
What is diffusion?
Diffusion is the movement of molecules from high to low concentration. Only small, uncharged, or lipid-soluble molecules can pass directly through the phospholipid bilayer.
Examples include O₂, CO₂, and ethanol.
What is facilitated diffusion?
Facilitated diffusion is the transport of larger or charged molecules using carrier proteins or protein channels.
What is osmosis?
Osmosis is the diffusion of water through a selectively permeable membrane, moving from high water potential to low water potential. It is a passive process.
What is active transport?
Active transport is the movement of substances against their concentration gradient, requiring ATP and carrier proteins (protein pumps).
An example is the sodium-potassium pump in nerve cells.
What is bulk transport?
Bulk transport, or vesicle transport, moves large molecules that cannot pass through the membrane.
What is endocytosis?
Endocytosis is when a cell engulfs large particles into a vesicle, using ATP. Types include phagocytosis (solid particles) and pinocytosis (liquids).
What is exocytosis?
Exocytosis is when a vesicle fuses with the cell membrane to release its contents outside the cell, using ATP.
How does the surface area to volume ratio (SA:V ratio) change with organism size?
As organism size increases, the SA:V ratio decreases. Smaller organisms have a larger SA:V ratio, leading to faster diffusion.
Why do larger multicellular organisms need specialized exchange surfaces?
Larger multicellular organisms need specialized exchange surfaces and transport systems to efficiently exchange materials with the environment.
What are the key takeaways regarding transport methods?
Passive transport does not require ATP (includes diffusion, facilitated diffusion, osmosis), while active transport requires ATP (includes active transport, endocytosis, exocytosis).
How does the SA:V ratio affect diffusion efficiency?
The SA:V ratio affects how efficiently materials are exchanged with the environment.
