This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Basics of DNA, Subject name: Biochemistry
Restriction endonuclease cleaves 
Select and explain. 
A. Double stranded DNA, B. Single stranded DNA, C. Single stranded RNA, D. Polypeptide
A: Double stranded DNA
Answer: A: Double stranded DNA 
Explanation: Restriction endonuclease Cleaves double stranded DNA at palindromic sites/ restriction sites 5' --AAGCTT-- 3'3' --TTCGAA-- 5' A palindromic sequence is a sequence which reads the same backwards as forwards. Found in bacteria Can create sticky ends or blunt ends Restriction endonuclease Sticky ends Blunt ends single-stranded overhangs no overhangs Example - EcoRI Example -SmaI