Exam 18: Regulation of Gene Expression

At the beginning of this century there was a general announcement regarding the sequencing of the human genome and the genomes of many other multicellular eukaryotes. There was surprise expressed by many that the number of protein-coding sequences was much smaller than they had expected. Which of the following could account for most of the rest?

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. -If she moves the operator to a position upstream from the promoter, what would occur?

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. -If she moves the operator to the far end of the operon (past the transacetylase gene), which of the following would likely occur when the cell is exposed to lactose?

Mutations in which of the following genes lead to transformations in the identity of entire body parts?

When DNA is compacted by histones into 10-nm and 30-nm fibers, the DNA is unable to interact with proteins required for gene expression. Therefore, to allow for these proteins to act, the chromatin must constantly alter its structure. Which processes contribute to this dynamic activity?

Which of the following experimental procedures is most likely to hasten mRNA degradation in a eukaryotic cell?

Altering patterns of gene expression in prokaryotes would most likely serve the organism's survival in which of the following ways?

In animals, embryonic stem cells differ from adult stem cells in that

Gap genes and pair-rule genes fall into which of the following categories?

A researcher introduces double-stranded RNA into a culture of mammalian cells, and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe. -Within the first quarter hour, the researcher sees that the intact RNA is found in the cells. After 3 hours, she is not surprised to find that

What would occur if the repressor of an inducible operon were mutated so it could not bind the operator?

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. -If she moves the repressor gene (lac I), along with its promoter, to a position at some several thousand base pairs away from its normal position, which will you expect to occur?

A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all. -Of the lines that express the transgene, one is transcribed but not translated. Which of the following is a likely explanation?

Since Watson and Crick described DNA in 1953, which of the following might best explain why the function of small RNAs is still being explained?

The bicoid gene product is normally localized to the anterior end of the embryo. If large amounts of the product were injected into the posterior end as well, which of the following would occur?

In prophase I of meiosis in female Drosophila, studies have shown that there is phosphorylation of an amino acid in the tails of histones of gametes. A mutation in flies that interferes with this process results in sterility. Which of the following is the most likely hypothesis?

Which of the following describes the function of an enzyme known as Dicer?

A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye. -Two children are born from the same parents. Child one inherits a predisposition to retinoblastoma (one of the mutations)and child two does not. However, both children develop the retinoblastoma. Which of the following would you expect?

A researcher has arrived at a method to prevent gene expression from Drosophila embryonic genes. The following questions assume that he is using this method. -The researcher measures the concentration of the polypeptides from different regions in the early embryo and finds the following pattern (darker shading = greater concentration): Which of the following would be his most logical assumption?

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. -She tried decreasing the amount of methylation enzymes in the embryonic stem cells and then allowed the cells to further differentiate. Which of the following results would she most likely see?