BIO 320: TRASNPORT ACROSS MEMBRANES
Diffusion....
-Dependent on solubility properties of the solute -Only involves transfer of small, nonpolar molecules
Active transport....
-Requires cellular expenditure of energy -Na+/K+ pump
You wish to dehydrate a piece of meat using solutions of varying salt concentrations. The best concentration is
10%
Th eNa+/k+ pump actively moves
3 Na+ out, 2 K+ in
Uptake of food particles by trapping them in within an invagination of the plasma membrane is called
Endocytosis
Which of the following is NOT a characteristic of active transport?
Exclusively move one molecule at a time in a unidirectional manner
The type of transport ATPase found in bacteria, mitochondria and chloroplasts are the ____________ ATPases.
F-type
One mechanism by which ions are specifically transported into the cell is the
Gated channel
Of the following molecules, which would NOT be expected to be moved across a membrane by simple diffusion?
Glucose
The bacteriorhodopsin proton pump creates a proton gradient that is needed in the process of an oxygenic photosynthesis. The energy necessary to drive this pump is generate by
Light energy
Which type of ATPase is associated with the integral binding of ATP as part of the transport process?
ABC type
Pumps are transporters that are able to harness energy provided by other components in the cells to drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called
Active transport
Transmembrane movement of a substance against a concentration gradient is called
Active transport
Animal cells use exocytosis to secrete all of the following except
Cell wall material
Although the extracellular environment has a high sodium ion concentration and the intracellular environment has a high potassium ion concentration, both must be neutralized by negatively charged molecules. In the extracellular case, what is the principle anion?
Cl
Cystic fibrosis is the result of a malfunction of the cell in transporting which of the following ions?
Cl-
A special class of ABC-type ATPases associated with tumors that allow movement of antibiotics and other drugs out of the cell are known as
Multidrug resistance transport protein
In cells H+ electrochemical gradients: which of the following H+ transporters regulates pH in animal cells?
Na+ and H+ exchanger
An example of indirect active transport is
Na+/glucose symport
Indirect active transport...
Na+/glucose symport
Voltage-gated channels contain charged protein domains, which are sensitive to changes in mbr potential. By responding to a threshold in mbr potential, these voltage sensors trigger the opening of the channels. Which describes the behavior of channels exposed to such a threshold?
Some channels stay closed + some open completely
Transporters, in contrast to channels, work by
Specific binding to solutes
The transport of two molecules across the cell membrane in the same direction is called
Symport
Which of the following is NOT a mechanism of active transport?
Unidirectional with gradients
The primary difference between active transport and facilitated diffusion is that active transport is the only one in which
[S]low----> [S]high
The transport of two molecules across the cell membrane in different directions is called
antiport
In some cells, it was noted that water moved faster than could be accounted for by simple diffusion. From this information, which of the following were identified and characterized?
aquaporins
In the kidney, the specialized transport proteins that allow for very rapid fluid movement into or out of cells are
aquaporins
Pores of the outer membrane of bacteria, mitochondria, and chloroplasts that are less specific and are formed by multiples transmembrane proteins are called
porins
Diffusion and passive and active transport...
requires a specific integral membrane protein
Both passive and active transport....
requires ligand binding and therefore Michaelis constants can be calculated
In all organisms, active transport across a membrane requires
An asymmetric distribution of ions across a membrane
None of the listed processes...
Applies only to ions
Mutations in bacterial porins can lead to antibiotic resistance typically by
Blocking entry of antibiotic
Transmembrane movement of a substance with a [gradient], with no involvement of membrane protein is
Diffusion
Both diffusion and passive transport...
Direction transport depends on the [gradient] any time
Ion channels are classified as membrane transport proteins. Channels discriminate by size and charge. In addition to Na+, which ions would you expect to be able to freely diffuse through a Na+ channel?
H+
In bacteria, the porins have the unique ability to transport
Hydrophilic of a particular size
A(n) _____________ solution is one that contains a solute concentration that is ____________ than that within the cell and results in the "bursting" of the cell.
Hypotonic, lower
Hungry yeast cell lands in a vat of grape juice and begins to feast on the sugars there, producing carbon dioxide and ethanol in the process. Unfortunately, the grape juice is contaminated with proteases that attack some of the transport proteins in the yeasts cell mar, and the yeast cell dies. Which of the following could account for the yeast cell's demise?
Inability to import sugar into the cell
The movement of water through a membrane, from an area of high concentration to an area of low concentration, is known as
Osmosis
Which of the following is NOT an example of facilitated diffusion?
Oxygen transport
The type of transport ATPase that are reversibility phosphorylated as part of the transport mechanism are ______ ATPases.
P-type
Transmembrane movement of a substance with a [gradient], utilizing a membrane protein is called
Passive transport or facilitated transport
Ca2+ pumps in the plasma membrane and ER are important for ____
Preventing Ca2+ from altering activity of molecules in cytosol.
Which of the following is NOT a characteristic of passive transport?
The energy for transport is generated by the molecular bonds of the substance being transported.
