When a typical restriction enzyme cuts a DNA molecule, the cuts are uneven, giving the DNA fragments single-stranded ends. These ends are useful in recombinant DNA work becausea. they enable a cell to recognize fragments produced by the enzyme.b. they serve as starting points for DNA replication.c. the fragments will bond to other fragments with complementary ends.d. they enable researchers to use the fragments as molecular probes.

What do restriction endonucleases do?

What is a plasmid?a. an organelle found in many bacteria and certain eukaryotesb. a circular DNA molecule that replicates independently of the main chromosome(s)c. a type of virus that has a DNA genome and infects certain types of human cells, including lung and respiratory tract tissued. a type of virus that has an RNA genome, codes for reverse transcriptase, and inserts a cDNA copy of its genome into cells

After finding a gene that causes a disease, researchers often introduce the defective allele into mice to create an animal model of the disease. Why are these models valuable?a. They allow the testing of potential drug therapies without endangering human patients.b. They allow the sequencing of the mutant allele.c. They allow the production of large quantities of the defective gene product, usually a protein.d. They allow the study of how the gene was transmitted from parents to offspring.

DNA technology has many medical applications. Which of the following is not done routinely at present?a. production of hormones for treating diabetes and dwarfismb. analysis of gene expression for more informed cancer treatmentsc. gene editing by the CRISPR-Cas9 system in viable human embryos to correct genetic diseasesd. prenatal identification of genetic disease alleles

Expression of a cloned eukaryotic gene in a bacterial cell involves many challenges. The use of mRNA and reverse transcriptase is part of a strategy to solve the problem ofa. post-transcriptional processing.b. post-translational processing.c. nucleic acid hybridization.d. restriction fragment ligation.

Which of the following sequences in double-stranded DNA is most likely to be recognized as a cutting site for a restriction enzyme?a. AAGGTTCCb. GGCCCCGGc. ACCATGGTd. AAAATTTT

A biochemist hopes to find a gene in human cells that codes for an important blood-clotting protein. She knows that the nucleotide sequence of a small part of the blood-clotting gene is CTGGACTGACA. Briefly outline a possible method she might use to isolate the desired gene.

A biologist isolated a gene from a human cell, inserted it into a plasmid, and inserted the plasmid into a bacterium. The bacterium made a new protein, but it was nothing like the protein normally produced in a human cell. Why? (Explain your answer.)a. The bacterium had undergone transformation.b. The gene did not have sticky ends.c. The human gene contained introns.d. The gene was not synthesized from scratch.