Cell Physiology Part 2 Flashcards
(22 cards)
What is facilitated diffusion via carrier 1 typically used for transporting?
Slightly Large polar molecules (e.g., Glucose, amino acids, nucleosides)
What are three key characteristics of facilitated diffusion via carrier type 2?
Specific carriers
Limited carriers (leading to saturation)
Competitive inhibition
Describe the relationship between solute concentration and transport velocity in facilitated diffusion via carrier type 2.
Transport velocity increases with solute concentration until all carriers are saturated, at which point the rate plateaus.
Name some ions that are transported via facilitated diffusion through ion channels.
Na⁺, K⁺, Cl⁻, Ca²⁺
What type of membrane proteins form ion channels?
Integral membrane proteins
What is a typical size characteristic of substances transported via ion channels?
Small size
What determines the selectivity of an ion channel for a specific type of ion?
Channel diameter
Charged and polar surfaces of the protein subunits
What two gradients influence the direction of ion movement through an ion channel?
Concentration difference
Electrical difference
What two factors determine the total number of ions that can pass through an ion channel?
How often the channel opens
How long it stays open
What is the key difference in the velocity of transport between an ion channel and a carrier protein?
Ion channels generally have a much higher velocity of transport compared to carrier proteins.
What are the three main types of stimuli that can cause ion channels to open (channel gating).?
Voltage-gated ion channel: changes in the membrane potential
Chemically-gated (ligand-gated) ion channel: the binding of specific molecules to channel proteins
Mechanically-gated ion channel: physically deforming the membrane
What causes a voltage-gated ion channel to open?
Changes in the membrane potential.
What causes a ligand-gated (extracellular ligand) ion channel to open?
The binding of a specific molecule (ligand) to the extracellular side of the channel.
What causes a ligand-gated (intracellular ligand) ion channel to open?
The binding of a specific molecule (ligand) to the intracellular side of the channel.
In what direction does active transport move substances relative to their electrochemical gradient?
Against its electrochemical gradient(uphill).
What causes a mechanically-gated ion channel to open?
Physical deformation of the membrane.
What are two characteristics of active transport regarding the substances it moves?
Binding to a substance
Specificity & Saturation
Name some ions that are moved via primary active transport.
Sodium, potassium, calcium, hydrogen, and chloride ions
Give two examples of primary active transport pumps.
Sodium-potassium pump (Na⁺-K⁺-ATPase) & Calcium pump
Is the sodium-potassium pump electrically neutral?
Not electrically neutral.
What are the two main functions of the Na⁺-K⁺-ATPase pump?
Maintain the characteristic distribution of high intracellular potassium and low intracellular sodium.
Controlling the volume of the cell.
What are the two types of secondary active transport?
Cotransport and Counter transport
