D) Long chains of amino acids used for building, repair, and maintenance
Proteins are made up of amino acids, and they are used to create substances (like hair, nails, etc.)
Hope this helps!!
<h2>Answer:</h2>
Bacteria provide genetic engineers with <u>_vector_ </u>and <u>_host_.</u>
<h3>Explanation:</h3>
Vector are vehicles or carriers which are used to carry the gene of interest. They are usually plasmids which are bacterial circular genome which can replicate independently.
Hence bacterial plasmids are used for the insertion of gene of interest and its transfer to the host cell.
As plasmids is taken from the bacteria, so mostly bacteria is used as the host for the gene of interest.
B. 2n.............................
The answer is the T tubules.
