Although all known cellular life and some viruses contain DNA, biologists in the early 1900's had difficulty identifying DNA as the genetic material because of its
apparent simplicity. Although it is a long polymer, it is only composed of four
subunits-A, T, C, and G. It wasn't until the 1940's that scientists came to the
conclusion that DNA was in fact the molecule that contained the genetic
material. In 2-3 sentences, describe how DNA molecules store genetic
information for cells.

your a sped   no one cares

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

: -)

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.