10. Transport I ppt Flashcards
(19 cards)
What is passive transport?
Transport of substances across cell membranes without the use of energy.
What are the types of passive transport?
- Simple diffusion
- Facilitated diffusion
- Osmosis
- Filtration
What facilitates passive transport?
Translocases – transmembrane proteins.
Define diffusion.
The process by which molecules intermingle due to their kinetic energy of random motion.
What does a concentration gradient refer to?
The net movement of molecules from a region of high concentration to a region of low concentration.
What is a gradient?
The change in the value of a quantity with the change in another variable.
What is Brownian motion?
The random motion of particles suspended in a fluid resulting from their collision with fast-moving atoms or molecules.
What is simple diffusion in the context of cell membranes?
Molecules move from higher concentration to lower concentration through spontaneous pores.
What types of molecules can undergo simple diffusion?
- Small polar molecules (e.g., water)
- Small and medium sized non-polar molecules.
What is the main obstacle for simple diffusion across cell membranes?
The hydrophobic region of the lipid bilayer.
What are Fick’s laws?
Laws that describe diffusion, stating that the molar flux due to diffusion is proportional to the concentration gradient.
What does Dm/dt represent in Fick’s laws?
The speed of diffusion.
What factors affect the index of diffusion (D)?
- Temperature (directly proportional)
- Viscosity of membrane (inversely proportional)
- Radius of particles (inversely proportional)
What is an example of diffusion in organisms?
Gas exchange: oxygen to RBC in alveoli and carbon dioxide from cells to RBC.
Is energy required for simple diffusion?
No ATP or light energy is required; only the energy in gradients.
What is osmosis?
The process by which solvent molecules pass through a semipermeable membrane from a less concentrated solution to a more concentrated one.
What is osmotic pressure?
The pressure required to prevent a pure solvent from passing into a given solution by osmosis.
Define osmol.
A non-SI unit of measurement that defines the number of moles of solute contributing to the osmotic pressure of a solution.
What is osmolarity?
The concentration of a solution expressed as the total number of solute particles per liter.
