31 Questions
Which type of transport requires energy expenditure by the cell?
Active transport
What is the primary energy source for active transport?
ATP
What determines the rate of facilitated diffusion?
Quantity of carrier proteins available
Which of the following most accurately describes "Transcellular (or Epithelial) Transport?"
Step 1 involves active transport. Step 2 involves either simple or facilitated diffusion.
What is the function of carrier proteins in facilitated diffusion?
To bind specifically to the molecule being transported
What is the purpose of channels in facilitated diffusion?
To allow the transport of ions and small hydrophilic molecules
Which type of transport involves the movement of molecules from high to low concentration?
Passive transport
What type of stimulus can open ion channels with a gate?
Voltage change, ligand, or mechanical stimulus
What is the name given to ion channels that are always open?
Leak channels
What is the main function of aquaporins in cells?
To aid water in crossing the cell membrane at a faster rate
In which type of cells are voltage gated channels present?
In all excitable cell types, including muscle, nerve, endocrine, and egg cells
What triggers the opening of ligand gated channels?
Ligand binding
What characteristic of lipid soluble molecules allows them to readily cross the phospholipid bilayer?
Being uncharged and non-polar
What is the minimum membrane potential required to trigger an action potential?
Channel threshold
What determines the rate of water crossing the phospholipid bilayer?
The type of cell
What is a characteristic of channels in membrane proteins?
They have an opening through the internal and external part of the cell membrane
What is the direction of ion movement in passive transport?
From high to low concentration
What is the primary function of membrane proteins in cell transport?
To act as a channel or transport/carrier protein
What is an example of a ligand-gated channel?
Acetylcholine binding to a nicotinic receptor within skeletal muscle cells
What type of molecules have a high permeability in the lipid bilayer?
Small hydrophobic molecules
What type of energy is used in passive transport?
Kinetic energy
What is the amount of pressure required to stop osmosis called?
Osmotic pressure
What is the result of a hypotonic solution on a cell?
The cell will expand and possibly rupture
Approximately how many types of aquaporins are found in mammalian cells?
13
What is the net movement of water based on the difference in water concentration across a membrane called?
Osmosis
What is the primary difference between exocytosis and endocytosis?
The direction of transport across the cell membrane
What is the name of the process by which cells internalize small particles?
Pinocytosis
What is the mechanism by which potassium is transported from the bloodstream to the interstitial fluid?
Active transport using the sodium-potassium pump
What is a function of receptor-mediated endocytosis?
To mediate the uptake of cholesterol
Which of the following is NOT a type of exocytosis?
Pinocytosis
Co-tranport (AKA: symport) and Counter-Transport (AKA: Antiport) are examples of which of the following?
Secondary active transport
Test your understanding of cell transport, the movement of substances across the cellular membrane, and the properties of lipid and water soluble molecules. Learn how the phospholipid bilayer affects the transport of different molecules.
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