The cell membrane forms a compartment, or cell, that is separate from the extracellular environment. What is the other main function of the cell
... [Show More] membrane?
controlling the transport of substances in and out of the cell
Due to the composition of the cell membrane, some molecules can cross the membrane more easily than others. This is called relative permeability. Which type of molecule is LEAST able to cross the membrane without transporters?
ions
Which type of molecular can diffuse across the cell membrane?
hydrophobicity
Which types of molecules are transported by aquaporins?
water
These channel and carrier proteins mainly transport molecules passively. Active transport, on the other hand needs energy. Why does active transport require energy?
it transports molecules against an electrochemical gradient
Which 3 transporters can let IONS into a cell?
1) Mechanically-gated on channels (opens in response to local deformation of the membrane)
2) Ligand-gated ion channels (opens in response to a ligand binding)
3) Voltage-gated ion channels (opens in response to an electrical signal)
Molecules requiring carrier proteins can use which 3 transporter proteins to get into a cell? CARRIER TRANSPORTERS
1) Symporter carrier protein (carrier molecule that transports 2 molecules in the SAME direction)
2) Uniporter (transports 1 molecule in 1 direction)
3) Antiporter (transports multiple cargoes in opposite directions)
Transporting molecules against the electrochemical gradient requires energy. These molecules are transported by:
1) ATP-driven pumps
2) light-driven pumps
3) coupled transport (uses the transport of a molecule traveling down the electrochemical gradient to drag another molecule against the electrochemical gradient)
Which of these options is not a mechanism to control the opening and closing of ion channels?
ATP binding (ATP gated)
How does coupled transport allow a molecule to be transported against the electrochemical gradient?
a co-transported molecule travels down an electrochemical gradient in either direction
Why do we need to label the membrane?
to visualize the cell membrane using the fluorescent microscope
Are the molecules able to cross the membrane?
yes, because there is green fluorescence in cells
Certain scorpions produce a toxin that inhibits Na+ channel closing. Now that you have identified the role of Na+ channels in nerve cells, can you predict the effect of the scorpion toxin on neural function?
hyper-excitability: more Na+ flows into the cell, causing neurons to fire more readily
lungs
Cl- ion channels allow Cl- and water to flow out of the cell. This creates a layer of mucus on top of the cells where they are in contact with the air. This mucus helps protect and clean the organ
nerve
To send an electrical signal, Na+ enters the cells through a Na+ ion channel to generate a positive charge. The Na+ is pumped out of the cells by the Na+/K+ ATPase to restore the resting state
kidney
Na+ is pumped out of the tubule cells into the bloodstream by the Na+/K+ ATPase to create a concentration gradient that allows reabsorption of other molecules from urine into the bloodstream via coupled transport
muscle
when the nerves deliver a signal to contract, Ca2+ rushes into the cell. The Ca2+ influx causes specialized fibers to contract. Afterward, Ca2+ is pumped out of the cell by a Ca2+ ATPase [Show Less]