Study the depiction of the lac operon in Figure 11.2. Normally, the genes are turned off

Your bone cells, muscle cells, and skin cells look different because a. different kinds of genes are present in each kind of cell. b. they are present in different organs. c. different genes are active in each kind of cell. d. different mutations have occurred in each kind of cell.

A group of prokaryotic genes with related functions that are regulated as a single unit, along with the control sequences that perform this regulation, is called a(n) ______________.

The regulation of gene expression must be more complex in multicellular eukaryotes than in prokaryotes because a. eukaryotic cells are much larger. b. in a multicellular eukaryote, different cells are specialized for different functions. c. prokaryotes are restricted to stable environments. d. eukaryotes have fewer genes, so each gene must do several jobs.

A eukaryotic gene was inserted into the DNA of a bacterium. The bacterium then transcribed this gene into mRNA and translated the mRNA into protein. The protein produced was useless and contained many more amino acids than the protein made by the eukaryotic cell. Why? a. The mRNA was not spliced as it is in eukaryotes. b. Eukaryotes and prokaryotes use different genetic codes. c. Repressor proteins interfered with transcription and translation. d. Ribosomes were not able to bind to tRNA.

How does dense packing of DNA in chromosomes prevent gene expression?

What evidence demonstrates that differentiated cells in a plant or animal retain their full genetic potential?

The most common procedure for cloning an animal is __________.

What is learned from a DNA microarray?

Which of the following is a substantial difference between embryonic stem cells and the stem cells found in adult tissues? a. In laboratory culture, only adult stem cells are immortal. b. In nature, only embryonic stem cells give rise to all the different types of cells in the organism. c. Only adult stem cells can be made to differentiate in the laboratory. d. Only embryonic stem cells are in every tissue of the adult body

Name three potential sources of stem cells

What is the difference between oncogenes and proto-oncogenes? How can one turn into the other? What function do proto-oncogenes serve?

A mutation in a single gene may cause a major change in the body of a fruit fly, such as an extra pair of legs or wings. Yet it takes many genes to produce a wing or leg. How can a change in just one gene cause such a big change in the body? What are such genes called?

Study the depiction of the lac operon in Figure 11.2. Normally, the genes are turned off when lactose is not present. Lactose activates the genes, which code for enzymes that enable the cell to use lactose. Mutations can alter the function of this operon. Predict how the following mutations would affect the function of the operon in the presence and absence of lactose: a. mutation of regulatory gene; repressor will not bind to lactose b. mutation of operator; repressor will not bind to operator c. mutation of regulatory gene; repressor will not bind to operator d. mutation of promoter; RNA polymerase will not attach to promoter

The human body has a far greater variety of proteins than genes, a fact that seems to highlight the importance of alternative RNA splicing, which allows several different mRNAs to be made from a single gene. Suppose you have samples of two types of adult cells from one person. Design an experiment using microarrays to determine whether or not the different gene expression is due to alternative RNA splicing.

Because a cat must have both orange and non-orange alleles to be tortoiseshell (see Figure 11.4), we would expect only female cats, which have two X chromosomes, to be tortoiseshell. Normal male cats (XY) can carry only one of the two alleles. Male tortoiseshell cats are rare and usually sterile. What might you guess their genotype to be?

Design a DNA microarray experiment that measures the difference in gene expression between normal colon cells and cells from a colon tumor.

Interpreting Data Review Table 11.1, which lists the number of diagnoses and the number of deaths for many types of cancer. We can estimate the deadliness of each type of cancer by dividing the number of deaths by the number of cases. (This is not accurate, however, because someone diagnosed during a particular year will not necessarily die during that same year, but it is a useful approximation.) If nearly everyone who received a diagnosis of one particular type of cancer dies, that ratio will be near 1 (or 100% deadly). If many more people receive diagnoses than die, the ratio will be near 0 (or near 0% deadly). Using this criteria, which two forms of cancer listed are the deadliest? The least deadly? What is the overall ratio for all types of cancer? What does this tell you about cancer survivability in general?

A chemical called dioxin is produced as a by-product of certain chemical manufacturing processes. Trace amounts of this substance were present in Agent Orange, a defoliant sprayed on vegetation during the Vietnam War. There has been a continuing controversy over its effects on soldiers exposed to Agent Orange during the war. Animal tests have suggested that dioxin can cause cancer, liver and thymus damage, immune system suppression, and birth defects; at high dosage it can be lethal. But such animal tests are inconclusive; a hamster is not affected by a dose that can kill a much larger guinea pig, for example. Researchers have discovered that dioxin enters a cell and binds to a protein that in turn attaches to the cells DNA. How might this mechanism help explain the variety of dioxins effects on different body systems and in different animals? How might you determine whether a particular individual became ill as a result of exposure to dioxin? Do you think this information is relevant in the lawsuits of soldiers suing over exposure to Agent Orange? Why or why not?

There are genetic tests available for several types of inherited cancer. The results from these tests cannot usually predict that someone will get cancer within a particular amount of time. Rather, they indicate only that a person has an increased risk of developing cancer. For many of these cancers, lifestyle changes cannot decrease a persons risk. Therefore, some people consider the tests useless. If your close family had a history of cancer and a test were available, would you want to get screened? Why or why not? What would you do with this information? If a sibling decided to get screened, explain whether you would want to know the results.