Question

Example of restriction endonuclease that produce blunt ends

Answer 1

Restriction endonucleases which produce blunt ends are without or have absence of single stranded sequences, these are the second group of endonucleases where the both strands of DNA or deoxyribonucleic acids are cut at the same specific place so that single stranded pieces ar not left on the ends of it, therefore, unlike their counterparts produce blunt instead of sticky ends. An example of it, include Sma1 (1 is in roman) from Serratia marcescens and Sca1 (1 is in roman) from Streptomyces caespitosis, all belong to the category of second group endonucleases which produce blunt or non-sticky ends.
Fragments with blunt ends may be or might get used as such. Small linkers are sometimes added to the ends for separation of the specific genes later in. Blunt ends are also made sticky ends or cohesive ends, to increase its cohesiveness or stickiness poly A and poly T sequences are added to gene editing or coding with the special help of enzyme terminal transferase.

Answer 2

Answer

• Some restriction enxzymes cut DNAs along the axis of symmetry of the restriction sites.

• They break two phosphodiester bonds, one in either strand of the restriction site at the axis of symmetry.

• Hence two blunt ends are formed.

• Eg: Alu I ,Bal I

• Several restriction enzymes cut one strand at left side of the axis of symmetry and the other strand at the right side of the axis.

• Then they break hydrogen bonds between basepairs lying between the two cyt sites.

• As a result, DNA fragments with single stranded extensions are formed.

• The single stranded rxtensions are called cohesive ends or sticky ends.

• The sticky ends of DNA fragments produced by restriction enzyme are complementary to each other.

• Eg: Eco RI, Bam HI