The correct answer is DNA microarray. In a DNA microarray, short DNA sequences (probes) are labelled on a microarray chip. Probes for the same gene are clustered in the same area on the array. cDNA from a sample is labelled with a fluorescent dye and washed over the chip. If a certain gene is more highly expressed, its cDNA will bind the respective probes and give a higher intensity than a lower expressed gene. 

The correct answer is whether the C-terminus of the protein is extracellular or intracellular. This is a very common laboratory technique to determine which terminus of a transmembrane protein is intracellular and extracellular. Since the antibody is specific to the C-terminus of the protein and if the C-terminus of the protein is intracellularly localized, we will only be able to detect the protein if the cells are permeabilized. In cells that are not permeabilized, the antibody will not be able to enter the cells, but permeabilization will allow the antibody to pass through the plasma membrane and bind the C-terminus. If the C-terminus is extracellular, the antibody will bind regardless of permeabilization.  

All of the given answers are valid methods to introduce exogenous DNA into a cell. When working with bacteria, transformations are a simple way to introduce plasmid DNA into the cell by chemical competency. Electroporation electrocutes both bacterial and cell culture cells to introduce exogenous DNA. Infection of target cells may also be a viable method if the laboratory is equipped to generate live virus containing exogenous DNA to be introduced. Finally, transfection refers to a process mainly reserved for cell culture that introduces exogenous DNA through liposome fusion (containing DNA) with cell membranes. 

Microarrays allow for the study of expression levels of thousands of genes simultaneously. Although microarrays do not tell you anything about the actual sequence of the genes, they are the only option for studying the expression levels of massive numbers of genes. It is possible to study expression levels using PCR, but not on a large scale.

Running allozyme gels was one of the first methods used in molecular studies of these enzymes that have slightly different functions due to having slightly different genetic codes (alleles). This term refers specifically to enzymatic variation created by genetic variation/alleles.

The correct answer is to separate proteins and other impurities from DNA or RNA. An extraction by phenol followed by chloroform will separate proteins and other impurities from DNA and RNA (in suspended fraction). Next, depending on the type and concentration of salt used, a researcher can selectively precipitate either DNA or RNA from the mixture with the addition of ethanol. This is a simple method to obtain pure clean ribonucleic acids from impure sources. 

The correct answer is lysis of the plasma membrane. While detergents such as sodium dodecyl sulfate are commonly used in western blots as a protein denaturing agent, it also breaks down the plasma membrane by emulsifying membrane-bound lipids and proteins.  

If the  of a reaction is less than zero, the reaction will in fact be exergonic. These reactions will be favorable and spontaneous, and energy is released in these reactions. Thus, endergonic is incorrect. 

The temperature and pressure of the reactants and products of any given reaction will determine the value of . However, this is entirely dependent of the reaction rate, which is determined by how the concentrations of the reactants and products change over the course of the reaction. Additionally, every reaction is unique, so "one-half" or any other exact metric cannot be applied as the definition. 

In equilibrium, both the forward and reverse reactions continue to occur, but they do so in a way that is equal and thus, there is no net change of reactants and products in the system.  is zero in this case because net changes to the system have ceased, and thus the free energy is no longer in flux.