The correct answer is d. 3.5 billion years.
Prokaryotes were the first forms of life on Earth long before simple multicellular life appeared because of their ability to withstand extreme conditions. It is believed that the first living forms were bacteria combined with archaea in the microbial mat (multi-layered sheet).
<span>pernicious form of anemia</span>
I believe that it's Bilateral symmetry. Hope it's right. :)
Answer:
D) Because sticky ends can be temporarily held together by hydrogen bonding between the two strands.
Explanation:
Restriction enzymes cut the DNA at specific restriction sites and by the mechanism of action they can form two types of ends:
- sticky ends-single-stranded overhangs are formed
- blunt ends-without overhangs.
The main advantage of sticky ends (their overhangs) is that they can complementary bind to another overhand formed by the same restriction enzyme. So, for example in cloning, if the DNA of interest and plasmid vector are cut with the same restriction enzyme, that forms sticky ends, fragment of DNA will fit into a bacterial plasmid in one direction.
On the other hand, blunt ends can be inserted into vector in both directions: head-to-tail or tail-to-head.
