Question

The term 'chimeric DNA' refers to
(А) DNA with overhanging stretches
(B) DNA with palindromic sequence
(C) A recombinant DNA
(D) Molecular scissors

Answer 1

DNA is a long polymer of deoxyribonucleotides. It is an acidic substance present in the nucleus, which was first identified by Friedrich Meischer in 1869. He named it "Nuclein". Altmann found these substances to be acidic in nature, hence he named it nucleic acid. The length of DNA is usually defined as the number of nucleotides or a pair of nucleotides referred to as base pairs (bp) present in it. This also is the characteristic of an organism.

Complete answer:
In prokaryotes, DNA is not scattered throughout the cell although they do not have a defined nucleus. DNA is found in cytoplasm in the super coiled stage. The coils are maintained by non-histone basic protein polyamine which has a positive charge. The packaged structure of DNA is called nucleoid or gonopore eukaryotes, this organisation is much more complex and is carried out by a set of positively charged basic proteins called histones.
Now let us know about types of DNA :-
DNA with overhanging stretches :- Some restriction enzymes (RE) Such as EcoRI cut the strand of DNA a little away from the centre of the palindrome sites, but between the same two bases on the opposite strands. This leaves single- stranded portions at the ends. There are overhanging stretches called sticky ends or cohesive ends on each strand.
DNA with palindromic sequence :- It is called Palindromic DNA. It has a base sequence which reads the same on both strands either in 5' to 3' or 3' to 5' directions. Different types of palindromic sequences are recognized by restriction endonucleases.
A recombinant DNA :- restriction endonucleases are used in genetic engineering to form recombinant molecules of DNA . These are composed of DNA from different sources . These are called chimeric DNA.
Molecular scissors :- the restriction enzymes that serve as knives to cut genes into defined fragments . The first restriction endonuclease was Hind II. Thus this option is not correct.

Our required answer is C) A recombinant DNA.

Note: Repetitive DNA : It is the part of DNA which contains the same sequence of nitrogen bases repeated more than once in the genome. The area with a long sequence of short repetitive DNA is called satellite DNA because it separates out during density gradient ultracentrifugation as small dark bands.