Biology Practice Test: Biotechnology and Genetic Engineering

Each restriction enzyme recognizes a short, specific sequence and cuts the DNA there, often leaving sticky ends. Joining fragments is the job of DNA ligase, not restriction enzymes.

Small fragments slip through the pores of the gel more easily, so they move the farthest. The largest fragment is slowed the most and stays nearest to the wells.

The sugar-phosphate backbone is negatively charged, so DNA is attracted to the positive end of the gel. Opposite charges attract, so a positive molecule would move the other way.

PCR copies a chosen DNA segment over and over through cycles of heating and cooling, turning a trace amount into millions of copies. Gel electrophoresis separates DNA but cannot make more of it.

The insulin gene is spliced into a small circular plasmid, which is put back into bacteria; they then read the gene and make the human protein. Feeding insulin to bacteria does not give them the gene to make it.

DNA ligase forms the bonds that join two DNA pieces into one continuous strand. The restriction enzyme makes the cuts beforehand, and RNA polymerase is used in transcription.

The Bt gene codes for a protein that harms the caterpillars that eat the plant, so farmers can use less spray. It does not give the plant new abilities such as nitrogen fixation.

Almost all of the genes are in the nucleus, so the clone matches the nucleus donor. The surrogate mother only provides a place to develop and passes on no genes.

People have different lengths of repeated DNA regions, so matching band positions at several regions point to the same person. The number of bands or how far they travel alone says nothing about a match.

The guide RNA matches a target sequence, and Cas9 cuts there, so scientists can disable, remove or replace a specific gene. It works on DNA at one chosen location, not on the whole genome.