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Exam 11: How Genes Are Controlled

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Question 31

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Signal transduction pathways

A) are found strictly in multicellular organisms, which require cell-to-cell communication.
B) originally evolved in vertebrates.
C) are mechanisms of communication that probably evolved in ancient prokaryotes.

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Question 32

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Researchers wish to use RNAi to prevent the expression of the enzyme hexokinase in order to study its impact on glycolysis. Which of the following processes would still occur if the researchers used RNAi effectively to silence hexokinase expression?

A) folding of the hexokinase protein
B) translation of the hexokinase protein
C) transcription of the hexokinase gene

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Question 33

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Which statement regarding stem cells is false?

Small pieces of RNA that can regulate translation of mRNA are called

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. -Why don't the grafted hybrids produce apples with a blend of traits from the scion and the rootstock?

Which is likely to occur in E. coli cells that are grown in milk?

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

RNA interference (RNAi) can be used by

In plants, most differentiated cells retain

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 scientist hypothesizes that a new drug turns on a certain gene in a skin cell. Which of the following experiments would be the best to test her hypothesis?

In female mammals, the inactive X chromosome in each cell

The coding regions of a gene are called

Scientists are attempting to make a chicken look like a dinosaur ("dino-chicken") by using drugs or proteins to turn on certain homeotic genes in somatic cells during the development of a chicken embryo. If the scientists are successful in creating both male and female "dino-chickens," and then the "dino-chickens" mate, what type of offspring would the two "dino-chickens" have?

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. -What can you conclude from these data?

What is the proper order of events in the expression of a eukaryotic protein?

Which mechanism of controlling gene expression occurs outside of the nucleus?

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 permits a single gene to code for more than one polypeptide?

The lac operon of E. coli is ________ when the repressor is bound to ________.

Which statement regarding DNA packing is false?