Restriction enzyme recognition sites are often palindromes, reading the same in the 5' to 3' direction on both strands.
Correct Answer
True
True. Recognition sites are usually four to eight base pairs long and read identically on the two strands when each is read 5' to 3'. This symmetry lets many enzymes make matching staggered cuts.
Category: Molecular Cloning
Question 2
Bacteria make restriction enzymes to help them copy their own chromosomes.
Correct Answer
False
False. Bacteria make restriction enzymes as a defense, cutting up foreign DNA such as that of invading viruses. Copying their own chromosomes is the job of the replication enzymes.
Category: Molecular Cloning
Question 3
Naturally occurring plasmids can carry genes such as those for antibiotic resistance.
Correct Answer
True
True. Plasmids in bacterial populations such as E. coli often carry useful genes, including antibiotic resistance genes. Scientists exploit such genes to select bacteria that have taken up a plasmid.
Category: Molecular Cloning
Question 4
During DNA extraction, adding alcohol causes the DNA to come out of solution.
Correct Answer
True
True. DNA is not soluble in alcohol, so adding it makes the long DNA molecules precipitate as a stringy, gelatinous mass. This step follows breaking the cells open and removing proteins and RNA.
Category: Lab Techniques
Question 5
RNA is easier to keep intact in the lab than DNA because few enzymes can break it down.
Correct Answer
False
False. RNA is very unstable because RNA-degrading enzymes are common, including ones secreted by human skin. Researchers must work carefully to keep RNA samples intact.
Category: Lab Techniques
Question 6
In PCR, the extension step, in which DNA polymerase builds new strands, is carried out at about 72 °C.
Correct Answer
True
True. Extension at about 72 °C follows denaturation at about 95 °C and primer annealing at a lower temperature. PCR uses a heat-stable DNA polymerase that survives these repeated high temperatures.
Category: Lab Techniques
Question 7
In reproductive cloning, the nucleus of an egg cell is removed and replaced with a diploid nucleus from a body cell of the animal to be copied.
Correct Answer
True
True. The enucleated egg supplies the cytoplasm needed for early development, while the transferred nucleus supplies the genes. The cell is then stimulated to divide and form an embryo.
Category: Cloning and Transgenics
Question 8
Dolly the sheep lived for more than 20 years, far beyond the normal life span of a sheep.
Correct Answer
False
False. Dolly lived about six years and died of a lung tumor. Some have speculated that DNA from an older donor cell may have shortened her life.
Category: Cloning and Transgenics
Question 9
Embryonic stem cells can develop into many different cell types, such as muscle or nerve cells.
Correct Answer
True
True. This ability is why embryonic stem cells interest researchers who hope to replace damaged tissues. Cells derived from a person's own DNA would also avoid tissue-matching problems.
Category: Cloning and Transgenics
Question 10
Scientists first began genetically modifying bacteria, plants and animals in the 2010s.
Correct Answer
False
False. Genetic modification with recombinant DNA began in the early 1970s, when tools for cutting and joining DNA were developed. Organisms have been modified for research, medicine, agriculture and industry ever since.
Category: Cloning and Transgenics
Question 11
Testing a person for inherited mutations in the BRCA genes can show whether that person has a higher risk of breast and ovarian cancer.
Correct Answer
True
True. Certain BRCA mutations raise the likelihood of breast, ovarian and some other cancers. If a high-risk mutation is found, relatives can choose to be tested or to watch more closely for cancer.
Category: Medical Biotechnology
Question 12
Antibiotics such as penicillin are produced naturally by viruses.
Correct Answer
False
False. Antibiotics are made naturally by microorganisms such as fungi; penicillin comes from a mold. Industrial producers often genetically modify these fungal cells to raise their yield.
Category: Medical Biotechnology
Question 13
The thin cell wall of plant cells makes them easier to give foreign DNA than animal cells.
Correct Answer
False
False. Plant cells have a thick cell wall, which makes introducing DNA harder than in animal cells. This is one reason researchers use bacteria that naturally transfer DNA into plants.
Category: Agricultural Biotechnology
Question 14
Foreign genes in transgenic crops can spread to other plants through pollen and seeds.
Correct Answer
True
True. Because engineered genes can move to related plants by pollen and seeds, transgenic crops are tested extensively and monitored by government agencies. The goal is to protect ecological stability.
Category: Agricultural Biotechnology
Question 15
The FlavrSavr tomato was engineered mainly to resist insect pests.
Correct Answer
False
False. The FlavrSavr tomato, the first genetically modified crop sold to consumers, was engineered to soften and rot more slowly, giving it a longer shelf life. It did not stay on the market because of problems with growing and shipping it.
Category: Agricultural Biotechnology
Question 16
The mouse, the fruit fly and the nematode C. elegans are all widely used model organisms.
Correct Answer
True
True. Model organisms are studied in depth because what is learned about them applies to other species, including humans. Yeast and the plant Arabidopsis are other common examples.
Category: Genomics and Proteomics
Question 17
Single-gene mutations cause the majority of diseases in developed countries.
Correct Answer
False
False. Single-gene mutations account for only a small share of diseases, about 5 percent in developed countries. Most common diseases, such as heart disease, involve many genes plus environmental factors like diet.
Category: Genomics and Proteomics
Question 18
Genome-wide association studies search for single nucleotide polymorphisms that are linked to a disease.
Correct Answer
True
True. These studies compare the genomes of large groups of people with and without a disease. They reveal associations, which do not by themselves prove that a variant causes the disease.
Category: Genomics and Proteomics
Question 19
Metagenomics studies the genome of a single species grown in pure culture.
Correct Answer
False
False. Metagenomics studies the collective genomes of many species from one environment. It avoids pure culture, which fails for many microbes that live in mixed communities.
Category: Genomics and Proteomics
Question 20
Every cell type in a multicellular organism produces the same set of proteins.
Correct Answer
False
False. Although nearly all cells carry the same genes, different cell types express different genes and so make different proteins. The genome stays constant while the set of proteins varies.
Category: Genomics and Proteomics