Chapter 6 · Recombinant DNA & the Human Genome Project: practice questions

What is the benefit of the sticky ends produced when DNA is cut by restriction enzymes?

• AThey break down protein because they act as digestive enzymes
• BThey raise the temperature so that the DNA strands can separate
• CThey prevent fragments from sticking together because they are identical
• DThey help DNA fragments join together because they are complementary

How is recombinant DNA formed?

• ABy breaking DNA down into simple sugars
• BBy converting protein into DNA inside the cell
• CBy combining DNA from two different sources
• DFrom RNA only, without using any DNA

What is a plasmid?

• AThe cell membrane that surrounds the bacterium and controls what enters it
• BA protein in muscles that helps the fibres contract, like actin and myosin
• CA small circular DNA molecule in bacteria, separate from the main chromosome
• DA type of vitamin that the body needs in small amounts to stay healthy

Which is the correct order of steps for producing recombinant DNA?

• ATranslation of the gene into protein, then transcription of that protein into DNA, then cutting it with ligase
• BBuild a protein from the gene, then cut the gene with ligase, then cool the host cell until it divides
• CCut out the gene, insert it into a cut plasmid and join it with ligase, then introduce the plasmid into a host cell
• DIntroduce the empty plasmid into the host cell, then cut out the gene, then heat the cell to join them together

Where do restriction enzymes originally come from?

• AFrom viruses themselves, as a means of infection
• BFrom muscle cells, to digest old proteins
• CFrom green plants, as part of photosynthesis
• DFrom bacteria, as a defence against viruses

After the recombinant plasmid is introduced into the host bacteria, what happens?

• AThe bacteria multiply, express the gene, and produce the required protein
• BThe plasmid comes back out of the bacteria, taking the gene along with it
• CThe bacteria die immediately because the foreign gene is toxic to them
• DThe gene breaks down into free nucleotides before it can be expressed

The enzyme that forms the bonds sealing the sugar-phosphate backbone between DNA fragments is:

• ALigase (the joining enzyme)
• BThe heat-stable polymerase
• CAmylase
• DThe restriction enzyme

In an experiment, we cut the gene and the plasmid and put them together, but no stable joining occurred. What is most likely missing?

• AThe restriction enzyme
• BLigase (the joining enzyme)
• CMore heat
• DPCR primers

Dolly was made by placing the nucleus of a mammary cell from a white-faced sheep into an egg, with its nucleus removed, from a black-faced sheep. The embryo grew in a third, black-faced sheep. What did Dolly look like?

• AWhite-faced, like the sheep that gave the nucleus
• BBlack-faced, like the sheep that gave the egg
• CHalf white and half black, from two mothers
• DBlack-faced, like the surrogate mother sheep

What is the best explanation for why producing insulin with modified bacteria is better than extracting it from animals?

• ABecause animal insulin is more expensive and purer
• BBecause animals do not produce insulin
• CBecause bacteria produce large, cheap amounts of insulin identical to human insulin
• DBecause bacteria do not multiply