Exam 11: How Genes Are Controlled

Why can some plants be cloned from a single cell?

E. coli can synthesize the amino acid threonine or absorb it from the environment. In the thr operon, the repressor is active when it is bound to threonine. If an E. coli bacterium is in an environment where threonine is absent, will transcription of threonine synthesis genes take place? Why or why not?

A signal outside a cell triggers changes in the transcription and translation inside the cell through

There is a mutation in the operator of the trp operon in a cell such that the trp repressor is unable to bind to the operator. If tryptophan is added to the cell, what will happen?

Which is not a factor that contributes to normal cells becoming cancerous?

The figure below shows a normal cell transduction pathway. If the receptor weren't there, which of the following is the most likely outcome?

In thinking about their role in cell division, oncogenes are like the ________ of a car, while tumor-suppressor genes are like the ________ of a car.

Both prokaryotic and eukaryotic cells use ________ to turn certain genes on or off.

Mutations in the proto-oncogene ras and the tumor-suppressor gene p53

Mutations in the p53 gene can lead to cancer by

Gene knockdown is a procedure used to reduce gene expression in cells or organisms so that scientists can investigate gene function. While there are several ways to knock down gene expression, RNAi is one of the most commonly used approaches. Suppose that a research team wants to investigate where a new gene X is expressed in the fruit fly, Drosophila melanogaster. Using RNAi, they obtained the results shown below examining the expression of gene X in four types of tissues. -Which of the following components could the researchers have used to successfully perform RNAi against gene X?

Which statement about microarrays is false?

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. -Which of the following statements regarding the comparison of DNA microarrays and qPCR is false?

RNA splicing involves the

The Pax6 gene codes for a transcription factor that initiates differentiation of cells that ultimately form the eye. Suppose that a researcher added an activator for the Pax6 gene to embryonic cells that are in the process of forming legs in Drosophila. What do you think the researcher will observe?

A cell has a mutation in both alleles of its p53 gene that causes the p53 protein to be three times as effective as normal. What do you predict would happen to this cell?

A gene operon consists of

Which possible use of reproductive cloning is still considered by most to be an unresolved ethical issue?

Which mammal has not yet been cloned and brought through the complete gestation cycle?

A single cell, the zygote, can develop into an entirely new organism with many different specialized cells. Which of the following statements about this process is false?