The successful use of the drug implies that the mRNA is degraded before it can be used in translation. As a result, the tRNAs used for the translation would not be mobilized for use on translating ribosomes, but transcription of mRNA would be unimpeded. The protein gene would be transcribed, the mRNA would be modified and leaves the nucleus, and would then be degraded before any synthesis could occur.

The temperature sensitive (Ts) mutation to a given gene results in a less stable protein product. At higher temperatures the protein does not fold properly or "melts," resulting in an improper structure of the protein. In turn, this improper structure will inhibit its function.

The Ts mutation will only affect a single gene, and is unlikely to affect global functions or cause apoptosis. Very few genes are only required at specific temperatures (genes required for stress response is an example). It is possible that the gene in question is required only at the restricted temperature, however, this is not the likely cause.

rRNA is an important building block of ribosomes, which synthesize proteins.

The anticodons of tRNA (not mRNA) bind to codons of mRNA (not rRNA), allowing ribosomes to tie together amino acids shuttled in on tRNA molecules. Many ribosomes are bound to the rough endoplasmic reticulum, but are not commonly bound to the membrane of the cell.

Proteins are translated from mRNA by ribosomes. Ribosomes are located on the surface of the rough endoplasmic reticulum, as well as in the cytoplasm. Inter-membrane proteins are constructed by the rough endoplasmic reticulum and sent off in a vesicle, which later becomes part of the cell surface. Generally, proteins created by cytoplasmic ribosomes are destined to serve as cytoplasmic proteins.

Plasma membranes of the cell are permeable to molecules that pass through the phospholipid bilayer easily, namely small nonpolar molecules. Due to this specificity in permeability, membrane proteins are often required to transport molecules across the bilayer. Simple diffusion occurs when a substance passes through a membrane without the aid of an intermediary. All forms of facilitated transport, along with active transport, require the aid of specific membrane proteins. Thus, simple diffusion is the correct answer.

The sodium-potassium pump serves to move three sodium ions out of the cell and two potassium ion into the cell.  These ions both have a plus one charge, so when the pump functions, it creates an environment where there are more solutes on the outside of the cell.  if it stopped working, the cell would stop moving sodium out, and since it is a polar molecule, it can't cross the cell membrane on its own.  There would be more solutes inside the cell than on the outside, and water would flow into the cell towards the higher solute concentration, causing the cell to swell and lyse.

Active transport most correctly describes this type of movement, as it uses ATP as an energy source. In contrast, the other four choices are all different types of passive transport, constituting types of movement where no energy source is needed. Diffusion is simply the net movement of particles down their concentration gradient. Facilitated diffusion is a similar concept, but uses specialized transport proteins. Osmosis describes the movement of water, and lastly, filtration is the movement of both solute and water molecules.

To answer this question you need to know the directionality of the sodium-potassium pump and the number of ions pumped each cycle. Remember that each cycle of the sodium-potassium pump moves three sodium ions to the outside of the cell and two potassium ions to the inside of the cell. The amount of sodium ions outside the cell will increase by three and the amount of potassium ions inside the cell will increase by two.

The final result after one cycle of the sodium-potassium pump will be 33 sodium ions outside the cell and 22 potassium ions inside the cell.

When a membrane channel, such as the sodium-potassium pump, requires energy (ATP) to transport molecules it means that the channel is moving molecules against their concentration gradient. This mode of transport is called active transport.

Recall that the sodium-potassium pump moves three sodium ions out of the cell and two potassium ions into the cell per cycle. Since it uses active transport, the sodium-potassium pump must move both sodium and potassium ions against their respective concentration gradients. This means that the concentration of sodium ions is greater outside the cell and the concentration of potassium ions is greater inside the cell.

Note that symporters exist in which facilitated diffusion of one ion is used to pull a second ion against its concentration gradient without the use of ATP. In this manner, ATP is not always necessary to transport an ion against its concentration gradient. When both ions are moving against their gradients, however, or when only one ion is being transported, ATP will be needed.

Antiporters are proteins that carry molecules in opposite directions, whereas symporters are proteins that carry molecules in the same direction. The sodium-potassium pump transports sodium ions out of the cell and potassium ions into the cell. The movement of ions occurs in opposite directions; therefore, the sodium-potassium pump is classified as an antiporter.