Which of the following sequences in double-stranded dna is most likely to be recognized as a cutting site for a restriction enzyme?
a. aagg
ttcc
b. ggcc
ccgg
c. acca
tggt
d.

b. GGCC

CCGG

Explanation:

Restriction enzyme cleaves DNA at the restriction site. Restriction site has 4-8 nucleotide base pairs which are recognized by the restriction enzyme. This site usually has a palindromic sequence which means that the sequence is read as same on both the strands in 5' to 3' direction. Palindromic sequence is used because it increases the chances that both the strands are cut. Enzyme is also able to recognize the sequence no matter from which side it approaches the DNA. The enzyme also works as homodimers sometimes so having the same sequence makes the dimers easier to recognize it. Here, the sequence is GGCC in 5' to 3' direction on both the strands making it a palindromic sequence. Hence it is most likely to be recognized as a cutting site for a restriction enzyme.  

it's not c. i took the quiz and got it wrong. so my best guess is b.

have a great day, and hope this .

the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.