Question

DNA libraries containing small pieces of DNA are usually propagated using bacterial ______. When libraries contain large fragments of DNA, they are usually propagated using bacterial or yeast ______ chromosomes?

1) plasmid
2) vector
3) genome
4) nucleus

Answer 1

Option (1), DNA libraries with small DNA fragments use bacterial plasmids for propagation, whereas libraries with larger DNA fragments use artificial chromosomes, either bacterial or yeast based, for propagation.

Step-by-step explanation:

DNA libraries containing small pieces of DNA are usually propagated using bacterial plasmids. When libraries contain large fragments of DNA, they are usually propagated using bacterial or yeast artificial chromosomes. Therefore, the answers to the blanks in the student's question are: 1) plasmid 2) artificial chromosomes. Cloning of DNA into plasmids is common for small genome fragments, allowing precise studies of genes.

For larger fragments, methods such as the use of Yeast Artificial Chromosome (YAC) systems allow for the inclusion of much larger pieces of DNA than can be accommodated by typical plasmid vectors. These YACs contain essential yeast chromosomal elements, such as one centromere and two telomeres, enabling the replication of these large DNA fragments within yeast cells.