Question

PLEASE ANSWER BOTH , AND ONLY IF YOU ARE SURE

1] Restriction endonucleases are: [ answer is not all of the above - answer can be more than one]

a] Bacteria keeps their own DNA modified preventing digestion by their own enzyme.

b] Scientists received Nobel Prize in 1978 for discovering restriction endonucleases.

c] Enzymes found in bacteria that digests DNA.

d] Each restriction enzyme recognizes a specific DNA sequence

e] Bacteria uses their own restriction enzymes for their defense against viral infection.

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!!!!!Question 41 Which of the following dye binds onto a DNA molecule externally?

a] Cyanin dye

b] Ethidium bromide.

c] Methyl green.

Answer 1

1. Options c and d are correct explaination of of what are restriction endonucleases. these are highly specific enzymes and cleave the dna by recognising specific sequences in the target. And they are found in bacteria. Their they are helping them to protect themselves from viral infection by cleaving the viral DNA.

2. Methyl green binds to DNA externally . It has an electrostatic interaction with the major groove of the DNA. It does not intercalate or insert in the DNA unlike other dyes.