Cell Physiology Flashcards
How does the concentration gradient affect diffusion?
The greater the concentration the faster the diffusion.
How does the size of the molecule affect diffusion?
Small molecules diffuse faster.
How does temperature affect diffusion?
Diffusion occurs faster when at a higher temperature due to there being more kinetic energy.
How does thickness affect diffusion?
Thin walls allows for faster diffusion.
How does surface area affect diffusion?
The greater the surface area the faster the diffusion.
What is simple diffusion?
The net movement of water from where it is a higher concentration to where it is a lower concentration.
What is facilitated diffusion?
This is the type of diffusion involved when the diffusion process is supported or ‘facilitated’ by proteins.
What are the two types of protein that are involved in facilitated diffusion?
Carrier proteins and (Ion) Channel proteins.
What are carrier proteins?
They take in diffusing molecules such as glucose, change shape and release the molecule on the other side of the membrane.
What are channel proteins?
Formed by proteins with a central pore that enables charged particles (ions) to pass through.
What is active transport?
Sometimes molecules and ions need to be moved across the membrane against the concentration gradient. Consequently energy is required. Active transport involves protein carrier molecules, which the substance binds to, the carrier then changes shape and is releases the transported substance on the other side of the membrane.
What are the differences between active transport and facilitated diffusion?
- Substances are moved against the concentration gradient.
- Metabolic energy in the form of ATP is required.
What is cytosis?
Substances that are transported into or out of the cell without having to pass through the membrane.
Cytosis is important for transporting…
Large molecules that are too big for carriers, and the bulk transport of smaller molecules (water).
What is endocytosis?
The movement of substances into the cell. (ENdocytosis ENter)
What is exocytosis?
The movement of substances out of the cell. (EXocytosis EXit)
What are the two types of endocytosis?
Phagocytosis and Pinocytosis
What is Phagocytosis?
The transport of solid material into a cell.
What is Pinocytosis?
Involves the transport of fluid into a cell.
What is Osmosis?
The net movement of water through a selectively permeable membrane, from a solution of less negative water potential to a more negative water potential.
What does water potential mean?
May be regarded as its tendency to take in water by osmosis from pure water across a selectively permeable membrane.
What is the water potential of pure water?
0 kPa
What is water potential an indication of?
The free energy of the water molecules.
What is formed around water molecules?
Hydration shells.
