Cell Membrane Transport (Diffusion) - Term 1 Flashcards
Week 2 - Diffusion
What are the three basic processes that result in transport into/out of the cell?
- Simple diffusion and facilitated and vesicular transport.
What is simple diffusion?
A passive process resulting from the random movement of ions and molecules directly through the bilayer.
- high concentration to low concentration.
What is facilitated transport?
A process that requires either channel or carrier proteins to diffuse large molecules through the cell membrane on their own
- passive or active transport
What is vesicular transport?
An active process in which materials are moved in membrane-bound sacs.
- Through endo, Pino, Phago, and exocytosis.
Why is vesicular transport an active process?
It requires energy to form the vesicles.
What is endocytosis?
When the membrane surrounds substances and pinches off to form a vesicle which is then suspended in the cytoplasm.
What is pinocytosis?
Entering of liquid substances into the cell via vesicular transport
What is phagocytosis?
Entering of solids substances into the cell via vesicular transport
What is exocytosis?
- Cells release substances using small bubbles called vesicles.
- These vesicles carry substances from the Golgi apparatus to the cell membrane.
- Once they reach the membrane, the vesicles merge with it, allowing their contents to spill out into the space outside the cell.
What does the rate of diffusion depend on?
The concentration gradient, the size and nature of diffusing molecules, the distance and area which diffusion takes place.
What does concentration gradient mean?
The greater the difference in concentration between two regions if the substances the greater the rate of diffusion.
What does the size and nature of diffusing molecules mean?
Smaller molecules diffuse faster than larger ones.
How does distance affect diffusion?
Short distances between the two regions of different concentrations lead to a greater rate of diffusion.
How does area affect diffusion?
A large surface area leads to a greater rate of diffusion.
What is Osmosis?
The diffusion of water via channel proteins in the cell membrane from low to high concentration.
- passive process.
What is the effect of Osmosis on cells?
Water moves from low to high solute concentration.
What is Osmotic pressure?
The pressure needed to keep it in equilibrium with pure water. High solutes in a solution lead to higher osmotic pressure.
Define extracellular fluid
The fluid that surrounds the immediate environment of a cell.
List the substances that all cells have to take in
All cells need to be supplied with oxygen and glucose.
What are the two types of carrier-mediated transport?
Facilitated diffusion and active transport
What effect does a hypnotic solution have on an animal cell?
The water enters causing the cell to swell and possibly burst.
What effect does a hypnotic solution have on a plant cell?
The water enters causing the cell to swell a bit and become turgid (inflated)
What effect does an isotonic solution have on an animal and plant cell?
There is no net movement of water and the cell remains the normal size.
What effect does a hypertonic solution have on an animal cell?
The water leaves, the cell shrinks and crenates
What effect does a hypertonic solution have on a plant cell?
The water leaves, the cytoplasm shrinks and plasmolyses.
