ELM 5 Electrochemical Gradients Flashcards
What is diffusion?
Diffusion is the passive movement of molecules or ions from an area of high concentration to an area of low concentration, down their concentration gradient.
Why does diffusion occur?
Diffusion occurs because of the natural tendency of molecules to move from regions of higher concentration to regions of lower concentration, driven by an increase in entropy.
How do ions move across membranes during diffusion?
Ions cannot cross lipid bilayers directly, so they require a pathway facilitated by molecules that create pores or channels in the membrane to facilitate diffusion.
What determines the rate of diffusion?
The rate of diffusion is determined by the concentration gradient, the surface area of the interface through which diffusion occurs, and the permeability of the medium.
What did Adolf Fick demonstrate about diffusion?
Adolf Fick showed that the number of molecules moving across an interface is proportional to the concentration gradient and the surface area of the interface.
What did Einstein contribute to the understanding of diffusion?
Einstein showed that diffusion is due to the random walk of molecules. The distance a diffusing molecule travels in a given time depends on the number of dimensions it can move in.
How does the dimensionality of diffusion affect the distance traveled by molecules?
Molecules diffuse further in three dimensions compared to one or two dimensions because there is a lower chance of them bumping into each other in a three-dimensional space.
How does diffusion in two dimensions impact cellular processes?
Diffusion in two dimensions, such as movement within a membrane, is important for processes like signal transduction, where molecules have a higher chance of interacting due to their proximity.
What are the implications of diffusion in three dimensions?
Diffusion in three dimensions allows signaling molecules to have longer ranges of action when not bound to membranes, facilitating communication over larger distances within organisms.
Where does movement occur in each dimension?
1 - along DNA.
2 - in membrane.
3 - in liquid.
What is electrophoretic movement?
Electrophoretic movement refers to the movement of ions in the presence of an electric field, where ions are attracted to electrodes of opposite charge.
How does electrophoretic movement influence ion movement?
Electrophoretic movement can either add to or subtract from diffusion, depending on the direction of the electric field and the charge of the ions.
What is the electrochemical gradient?
The electrochemical gradient is the combined effect of both the concentration gradient (caused by diffusion) and the electric field (caused by electrophoretic movement) on the movement of ions.
How does the charge distribution within cells influence ion movement?
Cells typically have a negative charge inside, creating an electrochemical gradient that can influence the movement of ions. For example, sodium ions (Na+) may experience a strong electrochemical gradient pushing them into the cell in addition to the force of diffusion.
What is Ohm’s law?
: Ohm’s law describes the relationship between voltage, current, and resistance in an electrical circuit, stating that current (I) equals voltage (V) divided by resistance (R), or I = V/R.
