Exam 11: How Genes Are Controlled

Yeast are able to communicate with each other

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?

After reading the paragraph below, answer the questions that follow. All apples in the United States, regardless of variety or where they're purchased, are produced by cloning. For more than 2,000 years, apple growers around the world have used a type of cloning called grafting to produce larger, better-tasting apples. Why has cloning become the primary method of apple growing? Apples grown from seeds usually don't produce apples with the same taste and appearance as that of the parent tree because there's a high degree of genetic variability among the seeds. Making identical genetic copies of the preferred fruit is the only way to get reliable apple quality. In grafting, the shoots and branches of the desired fruit, called a scion, are attached onto the trunk and root system of a previously existing tree, called the rootstock. Both components of the graft are needed because the rootstock controls gene expression in the scion, triggering production of apples that match the cloned scion. Grafting research can be used to produce some interesting tree combinations that are beneficial for intensive agriculture. For example, if you graft the root of a small tree variety, such as the crab apple, onto the shoot from a larger apple tree, such as the Gala, you can produce Gala apples on a much smaller tree. Other scientists are trying to create disease-resistant varieties that would need fewer pesticides. This is beneficial for the environment and also lowers the price of apples in the grocery store. -Half the trees in an orchard were derived from rootstock "A" and half from rootstock "B," but all the trees had the same scion. If the trees grafted onto rootstock "A" were infected by a parasite that causes blossom rot, the trees grafted onto rootstock "B"

A gene operon consists of

Enhancers are

Which of the following is likely to occur in E. coli cells that are grown in skim milk?

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?

RNA splicing involves the

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

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

RNA interference (RNAi)can be used by

A normal muscle cell produces the myosin protein, which allows muscles to contract. You discover a single muscle cell that has tRNAs that do not bind to amino acids. Will the myosin gene be expressed in this muscle cell? Why or why not?

Which of the following statements about proto-oncogenes is false?

Which of the following statements regarding stem cells is false?

There is a mutation in a promoter next to a gene such that RNA polymerase can never bind. What steps must occur for the gene to be transcribed?

Transcription factors attach to

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

The use of cloning to produce special embryonic stem cells is called

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

Which of the following statements about fruit fly development is false?