Engineering Life ■ 77viruses living organisms? Nonliving? If neither of those categories
fits the properties of viruses, how should they be classified?(^13) What do you think? Did Venter create “new life” by inserting
synthetic DNA copied from the genome of Mycoplasma mycoides
into a cell of Mycoplasma capricolum from which the DNA had
been removed? Be prepared to support your opinion in a class
discussion.
(^14) Doing science Go to the National Science Foundation website
(http://www.nsf.gov), and search for and read “Biologists Replicate
Key Evolutionary Step in Life on Earth” (Press Release 12-009,
January 16, 2012). State the hypothesis that the biologists were
testing, describe their experimental design, and explain their
results. Was their hypothesis supported? What experiment do you
think they should try next? State a hypothesis that you would test
using their multicellular yeast samples.
(g) This red blood cell is in a(n) (hypertonic / hypotonic / isotonic)
solution.
(h) In this environment, normal red blood cells (gain / lose / neither
gain nor lose) water.
(i) The total solute concentration outside the cell is (lower than /
higher than / equal to) the total solute concentration inside it.
Leveling Up
(^12) What do you think? Viruses display many of the characteristics
of living organisms. In particular, they reproduce, creating new
virus particles. During reproduction, viruses make copies of their
genetic material, and some of the copies contain mutations
that are beneficial to the virus. For example, HIV (human
immunodeficiency virus), the virus that causes the disease AIDS
(acquired immunodeficiency syndrome) mutates so often that
its surface proteins change faster than we can develop antiviral
drugs. New drug-resistant strains of HIV are appearing constantly.
However, viruses can reproduce only after entering a living cell
of an organism, because viruses hijack the cell’s machinery and
use it to produce new viruses. Where does that combination of
characteristics place viruses on the scale of nonlife to life? Are
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