What are some challenges of using mutations only to adapt to changing environmental conditions? How does gene regulation overcome these challenges?
What will be an ideal response?
Bacteria have two basic strategies for adaptation:
Mutations can produce desirable new traits, as is the case with mutations that make bacteria resistant to the antibiotics we take to kill them.
But there are three main issues with mutation:
1) mutations occur randomly. Because of this, they can be lethal if they make a vital protein inactive. The random nature of mutations also means that a lot of bacteria must die so that enough mutations can be tested to find the ones that are successful.
2) some desirable traits may actually require multiple mutations, which can take considerable time. Bacteria faced with a new and hostile environment may not have a lot of time to adapt.
3) imagine the environment changes again back to its original condition. Mutations are only reversible by additional rounds of mutations, which brings us back to the original two problems. So basically mutations are not an easy on/off switch.
A bacterium living in the real world must be able to alter multiple activities within minutes, then alter them back if conditions change once more. So in addition to mutation, bacteria also need a rapid, reversible strategy for change. This short-term strategy involves controlling which proteins are produced under a given set of conditions (i.e. gene regulation).
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A. is missing several important genes essential for DNA replication. B. requires protein factors found in blood. C. lacks numerous biosynthetic pathways and thus has numerous nutritional requirements. D. is missing the pathway for peptidoglycan synthesis.