Sticky end and Blunt end | Restriction patterns |
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DNA ends refer to the properties of the end of DNA molecules, which may be sticky ends (cohesive ends), blunt ends or in other forms. The concept is used in molecular biology, especially in cloning or when subcloning inserts DNA into vector DNA. Such ends may be generated by restriction enzymes that cut the DNA – a staggered cut generates two sticky ends, while a straight cut generate blunt ends.
sticky end :
A sticky or cohesive end has protruding single-stranded strands with unpaired nucleotides called overhangs, each overhang can anneal with another complementary one to form base pairs.
Longer overhangs are called cohesive ends or sticky ends. They are most often created by restriction endonucleases when they cut DNA. Very often they cut the two DNA strands four base pairs from each other, creating a four-base 5' overhang in one molecule and a complementary 5' overhang in the other. These ends are called cohesive since they are easily joined back together by a ligase. Also, since different restriction endonucleases usually create different overhangs, it is possible to cut a piece of DNA with two different enzymes and then join it with another DNA molecule with ends created by the same enzymes. Since the overhangs have to be complementary in order for the ligase to work, the two molecules can only join in one orientation. This is often highly desirable in molecular biology.
Blunt ends
The simplest DNA end of a double stranded molecule is called a blunt end. In a blunt-ended molecule both strands terminate in a base pair. Blunt ends are not always desired in biotechnology since when using a DNA ligase to join two molecules into one, the yield is significantly lower with blunt ends. When performing subcloning, it also has the disadvantage of potentially inserting the insert DNA in the opposite orientation desired. On the other hand, blunt ends are always compatible with each other.
DNA ends refer to the properties of the end of DNA molecules, which may be sticky ends (cohesive ends), blunt ends or in other forms. The concept is used in molecular biology, especially in cloning or when subcloning inserts DNA into vector DNA. Such ends may be generated by restriction enzymes that cut the DNA – a staggered cut generates two sticky ends, while a straight cut generate blunt ends.
sticky end :
A sticky or cohesive end has protruding single-stranded strands with unpaired nucleotides called overhangs, each overhang can anneal with another complementary one to form base pairs.
Longer overhangs are called cohesive ends or sticky ends. They are most often created by restriction endonucleases when they cut DNA. Very often they cut the two DNA strands four base pairs from each other, creating a four-base 5' overhang in one molecule and a complementary 5' overhang in the other. These ends are called cohesive since they are easily joined back together by a ligase. Also, since different restriction endonucleases usually create different overhangs, it is possible to cut a piece of DNA with two different enzymes and then join it with another DNA molecule with ends created by the same enzymes. Since the overhangs have to be complementary in order for the ligase to work, the two molecules can only join in one orientation. This is often highly desirable in molecular biology.
Blunt ends
The simplest DNA end of a double stranded molecule is called a blunt end. In a blunt-ended molecule both strands terminate in a base pair. Blunt ends are not always desired in biotechnology since when using a DNA ligase to join two molecules into one, the yield is significantly lower with blunt ends. When performing subcloning, it also has the disadvantage of potentially inserting the insert DNA in the opposite orientation desired. On the other hand, blunt ends are always compatible with each other.
7 سال پیش
در تاریخ 1396/05/22 منتشر شده
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