Several temperature-sensitive mutant strains of E. coli display the following characteristics. Predict what enzyme or function is being affected by each mutation. Newly synthesized DNA contains many mismatched base pairs.

Key Concepts

DNA Replication

DNA replication is the biological process by which a cell duplicates its DNA, ensuring that each daughter cell receives an exact copy of the genetic material. This process involves various enzymes, including DNA polymerases, which synthesize new DNA strands by adding nucleotides complementary to the template strand. Errors during replication can lead to mismatched base pairs, which are critical to understand in the context of mutations.

DNA Repair Mechanisms

Cells have evolved several DNA repair mechanisms to correct mismatched base pairs that occur during DNA replication. One key mechanism is the mismatch repair system, which identifies and repairs incorrectly paired nucleotides. Understanding these repair pathways is essential for predicting how temperature-sensitive mutations in E. coli might affect the fidelity of DNA synthesis and the overall stability of the genome.

Temperature-Sensitive Mutations

Temperature-sensitive mutations are genetic alterations that result in a phenotype that is only expressed at certain temperatures. In the context of E. coli, these mutations can affect the function of enzymes involved in DNA replication and repair, leading to increased errors such as mismatched base pairs at non-permissive temperatures. Recognizing how these mutations influence enzyme activity is crucial for predicting the effects on DNA synthesis.