How are the structures of RNA and DNA similar?
A. Their sugar-phosphate backbones are formed by phosphodiester linkages.
B. Adenine pairs with thymine in both.
C. They both have the same tertiary structure.
D. They both contain the sugar ribose.
Ans: A. Their sugar-phosphate backbones are formed by phosphodiester linkages.
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Which molecule catalyzes covalent bond formation between fragments of DNA.
A. helicase. B. ligase. C. polymerase. D. primase. E. nuclease.
You want to determine whether a person has a certain mutant gene. The process involves using restriction enzymes and a heat-stable DNA polymerase obtained from a thermophilic bacterium to amplify many copies of the gene. This process is
a. gel electrophoresis. b. shuttling vectors. c. PCR. d. site-directed mutagenesis.
The enzyme responsible for bioluminescence in bacteria is
a. bioluminase. b. photolyase. c. luciferase. d. phosphatase.
You are working in a human genetics laboratory that studies causes and treatments for eye cataracts in newborns
This disease is thought to be caused by a deficiency in the enzyme galactokinase, but the human gene that encodes this enzyme has not yet been identified. At a talk by a visiting scientist, you learn about a strain of baker's yeast that contains a mutation called gal1– in its galactokinase gene. Because this gene is needed to metabolize galactose, the mutant strain cannot grow in galactose medium. Knowing that all living things evolved from a common ancestor and that distantly related organisms often have homologous genes that perform similar functions, you wonder whether the human galactokinase gene can function in yeast. Because you have an optimistic temperament, you decide to pursue this line of experimentation. You isolate mRNA gene transcripts from human cells, use reverse transcriptase to make complementary DNA (cDNA) copies of the mRNA molecules, and ligate the cDNAs into circular plasmid DNA molecules that can be stably propagated in yeast cells. You then transform the pool of plasmids into gal1– yeast cells so that each cell receives a single plasmid. What will happen when you spread the plasmid-containing cells on Petri dishes that contain galactose as a carbon source? How can this approach help you find the human gene encoding galactokinase?