When you start the PCR amplification reaction, you have a template which has sequences where the primers will anneal. The forward primer anneals in the sense strand and the reverse one in the complementary sequence (see attached figure).
After the first PCR cycle, two types of fragments are obtained. First those which come from tha 5'-3' sequence, that are 3'-5' and will anneal the reverse primer in the following cycle. This fragments have the correct 3' end, but the 5' includes part of the template that doesn't correspond to our target (see attached figure)
Second, those fragments that come from the 3'-5' sequence, that are 5'-3' and will anneal the forward primer. This fragments also have the correct 3' end, but the 5' includes part of the template that doesn't correspond to our target (see attached figure).
Now, during the second cycle, are produced the first fragments that have the precise length of the sequence that we want to amplify (see attached figure).
So, it's not until the third cycle that the reaction starts amplifying exactly the sequence of desired length.
Elephant poaching is an example
One of the most important benefits that wetlands provide is their capacity to maintain and improve water quality. When healthy, wetlands have a rich natural diversity of plants and animals. These can act as filtering systems, removing sediment, nutrients and pollutants from water.
:D
Answer:I got it
Explanation:
Carbon Dioxide Concentrations in the Atmosphere Are Increasing
Global Temperature Rise
Shrinking Ice Sheets
Warming Oceans
Glacial Retreat
Decreased Snow Cover
Sea Level Rise
Declining Arctic Sea Ice
Ocean Acidification