When agarose gel electrophoresis is used to study DNA a DNA

When agarose gel electrophoresis is used to study DNA. a. DNA is loaded near the positive electrode because it is negatively charged. b. Pieces of DNA are separated by size, with larger sizes moving further. c. Molecular weight standards are not needed as the movement of DNA in agarose is well understood. d. DNA moves form the negative electrode towards the positive electrode because it is negatively charged. d. DNA moves from the negative electrode towards the positive electrode because it is negatively charged. e. Pulsed Field Gel Electrophoresis might be needed if the pieces are smaller than 10 kilobases. Type I and Type II restriction enzymes (Res) differ in that a. Prokaryotes have type I and eukaryotes have type II. b. Type I produce blunt ends and Type II produce staggered ends. c. Type I enzymes but 1000 base pairs away from the sequence they recognize whereas Type II cut within the recognition sequence. d. Type I enzymes cut only modified DNA but type II can cut any DNA. Restriction Fragment Length Polymorphisms: a. are identical between any two members of a species. b. are based on DNA bands observed after cutting with a restriction enzyme. c. are based on differences seen when changes in the sequence fail in a restriction enzyme recognition site. DNA probes used in a variety of experiments can be labeled for detection with all of the below EXCEPT: a. radioactive phosphate b. radioactive sulfur c. biotin d. digoxigenin e. all of the above can be used to label DNA The GC ratio of DNA is very important in many DNA technologies because: a. G and C will fluoresce whereas A and T will not. b. G and C will have 3 hydrogen bonds between them, resulting in a higher melting point. c. Restriction enzymes recognize sequences containing only G and C. d. The GC ratio is actually NOT important at al. To construct a gene library, DNA can be inserted into E. coli by: a. Transformation b. Electroporation

Solution

20. Answer d : . DNA fragment is negatively charged so they move towards positive electrode.

DNA larger than 25 kb can be detected by pulse field gel electrophoresis.

21. Answer c: Type I enzyme cut 1000 base pair away from the sequence they recognize

22. Answer d: Restriction fragment length is fragment of DNA cut by restriction enzyme that is different in length for each genetically related group and is used to trace family relationship.

23. Answer e. All can be used to label DNA

24. Answer b: Because of GC pair PCR amplification of DNA become difficult as this has higher melting point