The answer to this question is C. Depressants
Answer:
C. At least five mass-extinction events have occurred during the last 500 million years.
Explanation:
- The history of mass extinct is related to the five mass extinctions that are caused over by the 350 million years n which many species have disappeared in there short geologic time.
- A massive extinction is caused in the Permian Triassic extinction event i.e about 250 mn years ago which on an estimate has killed 90% of the species.
- The Cretaceous–Paleogene extinction event that occurred over 66 million years ago is known to have wiped out the dinosaurs and many other species.
During prophase, the complex of DNA and proteins contained in the nucleus, known as chromatin, condenses. The chromatin coils and becomes increasingly compact, resulting in the formation of visible chromosomes. Chromosomes are made of a single piece of DNA that is highly organized.
Answer:
DNA from a gene of interest can be inserted into a plasmid, then the modified plasmid can be inserted into a bacterial cell to replicate a gene of interest many times.
Explanation:
Plasmids are the extra-chromosomal circular DNA present in bacterial cells. Plasmids are able to replicate themselves independent of genetic DNA. Their ability to self replicate allows them to maintain themselves in the bacterial cells. This is why plasmids are used as cloning vectors in recombinant DNA technology.
A gene of interest is isolated from the donor cell and is inserted into the plasmid. The recombinant plasmid is introduced into bacterial cells where it replicates the ligated desired gene and allows the gene cloning. For example, the human insulin gene is ligated with plasmid and the recombinant plasmid is introduced in <em>E. coli</em> where it replicates the human insulin gene and allows the production of desired copies of the gene.
