Question

For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below. Not all words or phrases will be used; use each word or phrase only once.

Two fragments of DNA can be joined together by __________. Enzymes that cut DNA straight across the double helix produce fragments of DNA with ___________.

A) blunt ends
B) DNA polymerase
C) staggered ends
D) DNA ligase
E) vectors

Answer 1

DNA fragments with staggered or sticky ends can be joined together by DNA ligase; blunt ends refer to straight cut DNA fragments that can also be joined, albeit less efficiently. The enzyme responsible for splicing DNA and facilitating genetic engineering applications is DNA ligase, and vectors such as plasmids are used to transport DNA fragments.

Step-by-step explanation:

Two fragments of DNA can be joined together by DNA ligase. Enzymes that cut DNA straight across the double helix produce fragments of DNA with blunt ends. Conversely, enzymes that cut at specific sequences, creating overhangs, produce staggered ends, which are also known as sticky ends.

These sticky ends can anneal to complementary DNA fragments cut by the same restriction enzyme, and they are then permanently joined by the enzyme DNA ligase in the process known as ligation. This method is crucial in the formation of recombinant DNA, which is instrumental in various genetic engineering applications. Plasmids, which serve as vectors in gene cloning, can also carry these DNA fragments from one organism to another.