Question 1

Which of the following processes is most like the formation of identical twins?

Accepted Answer

Organismal cloning involves creating a genetically identical copy of an organism, similar to how identical twins are formed from the splitting of a single fertilized egg.

Question 2

Scientists developed a set of guidelines to address the safety of DNA technology. Which of the following safety measures is one that has been adopted by researchers?

Accepted Answer

Microorganisms used in recombinant DNA experiments must be genetically crippled to ensure that they cannot survive outside of the laboratory is a safety measure that has been adopted by researchers. The other options (B, C, and D) are either partially true or not completely accurate. Genetically modified organisms are allowed in the food supply in some countries, transgenic plants can hybridize with related wild species and gene flow can occur, and experiments involving potentially dangerous viruses are not entirely banned but are subject to strict safety protocols.

Question 3

Which of the following statements correctly describes one characteristic of genetically engineered plants?

Accepted Answer

Transgenic rice plants have been developed that can grow in water more salty than seawater, which is one example of genetically engineered plants. While genetically engineered plants are still subject to regulatory approval in some regions, they are currently used in commercial agricultural production.

Question 4

For a particular microarray assay (DNA chip), cDNA has been made from the mRNAs of a dozen patients' breast tumor biopsies. Which of the following types of evidence will researchers be looking for in order to determine if the cells are cancerous?

Accepted Answer

Researchers will be looking for a pattern shared among some or all of the breast tumor biopsy samples that indicates gene expression differing from control samples. This pattern of differential gene expression can be used as evidence to determine if the cells are cancerous or not.

Question 5

Suppose that a researcher is successful at producing induced pluripotent stem cells (iPS) for replacement of pancreatic insulin-producing cells for people with type 1 diabetes. Which of the following could still pose problems for this individual?
I.the possibility that, once introduced into the patient, the iPS cells produce non-pancreatic cells
II.the failure of the iPS cells to take up residence in the pancreas
III.the inability of the iPS cells to respond to appropriate regulatory signals

Accepted Answer

All of the listed possibilities could pose problems for the effectiveness of the iPS cells in replacing pancreatic insulin-producing cells for people with type 1 diabetes. If the iPS cells produce non-pancreatic cells, they will not be able to fulfill their intended function. If the iPS cells do not take up residence in the pancreas, they will not be able to function in the appropriate tissue microenvironment. Additionally, if the iPS cells are unable to respond to regulatory signals, their function could be impaired. Therefore, all of these possibilities need to be addressed in order to ensure the success of iPS cell therapy for type 1 diabetes.

Question 6

In recent times, it has been shown that adult cells can be induced to become pluripotent stem cells (iPS). To make this conversion, what has been done to the adult cells?

Accepted Answer

The technique used to induce adult cells to become pluripotent stem cells involves introducing four specific master regulatory genes into the adult cells using a retrovirus. This reprograms the adult cells to behave like embryonic stem cells, with the ability to develop into any type of cell in the body. This technology has revolutionized the field of regenerative medicine as it provides a source of patient-specific stem cells for research and potential therapies.

Question 7

In large scale, genome-wide association studies in humans, what types of genetic markers do researchers look for?

Accepted Answer

In genome-wide association studies, researchers typically look for single nucleotide polymorphisms (SNPs) where one allele is found more often in persons with a particular disorder than in healthy controls. These SNPs can be used as genetic markers to identify potential genetic factors contributing to the disorder.

Question 8

One possible use of transgenic plants is in the production of human proteins, such as vaccines. Which of the following issues is a possible hindrance that must be overcome in order for this process to work properly?

Accepted Answer

Transgenic plants producing human proteins must ensure that plant allergens do not cause adverse reactions in vaccine recipients.

Question 9

Which of the following problems with animal cloning might result in premature death of the clones?

Accepted Answer

Abnormal gene regulation due to variant methylation can lead to developmental abnormalities and premature death in cloned animals.

Question 10

A researcher is using adult stem cells and comparing them to other adult cells from the same tissue. Which of the following findings is likely from this comparison?

Accepted Answer

Adult stem cells and differentiated cells from the same tissue often exhibit different patterns of DNA methylation, which is a key mechanism in regulating gene expression and maintaining stem cell pluripotency.

Question 11

Which of the following statements describes one of the technical reasons why gene therapy is problematic in humans?

Accepted Answer

One of the technical challenges of gene therapy is ensuring that the transferred genes have appropriately controlled activity. This is because the introduced genes may interact with the host cell's genetic machinery in unpredictable ways, leading to unwanted effects like tumorigenesis or immune responses. Additionally, the expression of introduced genes may not be regulated in the same way as endogenous genes, which can cause toxicity or other issues.

Question 12

In a comparison of two DNA sequences found in the same location on homologous chromosomes, one of the homologs carries the sequence 5′-AACTACGA-3′, and the other homolog carries the sequence
5′-AACTTCGA-3′. Within a population, you discover that each of these sequences is common. Which of the following statements correctly describes theses sequences?

Accepted Answer

The two sequences differ by a single nucleotide polymorphism (SNP), specifically a substitution of T for C. This SNP can be used as a genetic marker for mapping loci of interest in the population. The other choices are not supported by the information given. There is no evidence that these sequences identify protein-coding regions or cause disease, nor is there any information suggesting that they are involved in RNA interference.

Question 13

In animals, what is the difference between reproductive cloning and therapeutic cloning?

Accepted Answer

The answer of In animals, what is the difference between...

Question 14

In 1997, Dolly the sheep was cloned. Which of the following processes was used?

Accepted Answer

Dolly the sheep was cloned using the process of somatic cell nuclear transfer (SCNT), which involved transferring the nucleus from an adult cell (in this case, a mammary gland cell) into an enucleated sheep egg (an egg cell with its own nucleus removed). The resulting egg was then implanted into a surrogate ewe's uterus and allowed to develop into a fetus. This technique allowed for the creation of a genetically identical animal to the adult donor, in this case, a sheep named Dolly.

Question 15

The first cloned cat, called Carbon Copy, was a calico, but she looked significantly different from her female parent. Why was this the case with this clone?

Accepted Answer

X chromosome inactivation in female embryos is a random process that can produce different patterns of gene expression. This means that even though Carbon Copy was genetically identical to her female parent, the inactivation of X chromosomes in her embryo could have led to differences in her fur color and other physical traits.

Question 16

Which of the following processes uses labeled probes to visualize the expression of genes in whole tissues and organisms?

Accepted Answer

In situ hybridization is the process that uses labeled probes to visualize the expression of genes in whole tissues and organisms. RT-PCR is a method of amplifying specific RNA sequences and is not used to visualize gene expression in tissues or organisms. DNA microarrays are used to measure the expression of many genes simultaneously but do not involve labeled probes. RNA interference is a process by which RNA molecules specifically silence target genes and does not involve visualization of gene expression in tissues or organisms.

Question 17

Which of the following statements correctly describes one of the main differences between embryonic stem cells and adult stem cells?

Accepted Answer

The main difference between embryonic stem cells and adult stem cells is that embryonic stem cells have the potential to differentiate into all cell types in the organism, while adult stem cells are limited to differentiating into a specific set of cell types. Option A is incorrect because embryonic stem cells can differentiate into any type of cell, not just eggs and sperm. Option C is incorrect because both embryonic and adult stem cells have the potential to reproduce for some time, but embryonic stem cells have a much greater capacity for self-renewal. Option D is incorrect because while using embryonic stem cells for tissue repair is one application being researched, it is not the only aim.

Question 18

Which of the following statements correctly describes how RNA interference (RNAi) silences selected genes?

Accepted Answer

RNA interference (RNAi) silences genes by triggering the degradation of messenger RNA (mRNA), which prevents protein synthesis. Synthetic double-stranded RNA molecules complementary to the target mRNA are introduced into the cell, leading to the formation of a RNA-induced silencing complex (RISC) that cleaves the mRNA and targets it for degradation.

Question 19

Reproductive cloning of human embryos is generally considered unethical. However, on the subject of therapeutic cloning, there is a wider divergence of opinion. Which of the following statements provides a likely explanation?

Accepted Answer

The potential medical benefits of therapeutic cloning are often cited as a reason for supporting it, despite ethical concerns about cloning embryonic stem cells.

Question 20

RNAi methodology uses double-stranded pieces of RNA to trigger breakdown of a specific mRNA or inhibit its translation. For which of the following processes might this technique be useful?

Accepted Answer

RNAi methodology can be used to decrease the production of a harmful mutated gene. By triggering the breakdown of the mRNA encoding the mutated protein, the production of the protein can be reduced, leading to a decrease in the harmful effects of the mutation.

Quiz 20: DNA Tools and Biotechnology