Exam 11: How Genes Are Controlled

There is a mutation in the operator of the lac operon in a cell such that the lac repressor always stays bound to the operator. If lactose is added to the cell, what will happen?

While DNA microarrays can be used to determine whether or not a gene is expressed in a cell, quantitative polymerase chain reaction (qPCR) can be used to specifically quantify the extent of gene expression in cells and tissues. To perform qPCR, mRNA is extracted from cells and reverse transcribed to complementary DNA (cDNA). Using fluorescent DNA molecules that recognize specific gene sequences and DNA polymerase, copies of the gene sequence of interest are made. After the copies are made, a fluorescent detector measures the intensity of the fluorescent signal, which is proportional to the number of mRNA transcripts in the cell and corresponds to the level of gene expression in the cell. -A pancreatic cell normally produces low levels of the protein insulin, but after a meal it produces large levels of insulin before returning to its initial state. Which of the following figures would represent qPCR data obtained from a pancreatic cell that went through this cycle?

Adult stem cells have limited therapeutic potential

Two yeast cells, one of type a and the other of type α, are in proximity to each other. The a yeast cell has a mutation in the gene for the α factor receptor protein such that the receptor does not translocate to the plasma membrane of the a cell. If both cells secrete their respective a and α factors, which of the following outcomes is most likely to occur?

A gene that can cause cancer when present in a single copy in a cell is called a(n)

The expression of the tryptophan operon is controlled by a(n)

Which molecules are not required to express a gene in eukaryotic cells?

Enhancers are

Transcription factors attach to

All of the trees in an orchard were derived from the same rootstock, but half had scion "A" grafted and the other half had a different scion, scion "B," grafted. The trees that were grafted with scion "A" developed large fruits. What characteristics do you think the fruit from the trees that were grafted with scion "B" will have and why?

In this drawing of the lac operon, which molecule is an inactive repressor?

All of the following mechanisms are used to regulate protein production except

To initiate a signal transduction pathway, a signal binds to a receptor protein usually located in the

A cell is expressing the mutant form of ras, but one of the downstream relay proteins is not present because of another mutation. How will cell division be affected in this scenario?

The development of colon cancer occurs slowly, and colon cancer is more frequently seen in the elderly than the young. This is most likely because

In a prokaryote, a group of genes with related functions, along with their associated control sequences, defines a(n)

Which process occurs when a salamander regenerates a lost limb?

The carcinogen known to cause the most cases and types of cancer is

Proteins that bind to DNA and turn on operons by making it easier for RNA polymerase to bind to a promoter are called

The term gene expression refers to the