Answer: We are evolving to the environment, and the changes around us. And those that don't die
Explanation:
They put pressure on us to adapt in order to survive the environment we are in and reproduce. It is selection pressure that drives natural selection ('survival of the fittest') and it is how we evolved into the species we are today. Genetic studies have demonstrated that humans are still evolving.
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.
Answer:
cell membrane, DNA and RNA, cytoplasm, and ribosomes
Explanation:
Bacteriophage means “eater of bacteria,” and these spidery-looking viruses may be the most abundant life-form on the planet. HIV, Hepatitis C, and Ebola have given viruses a bad name, but microscopic phages are the good guys of the virology world.