Molecular Basis of Inheritance — Important Questions

DNA gyrase, DNA topoisomerase I

DNA gyrase and DNA topoisomerase I are involved in maintaining the supercoiled state of DNA during packaging in prokaryotes. DNA ligase joins DNA fragments, RNA polymerase synthesizes RNA, and DNA helicase unwinds DNA.

Heterocatalytic - synthesis of RNA and proteins, Autocatalytic - synthesis of DNA itself

Heterocatalytic function involves DNA directing synthesis of molecules other than itself (RNA, proteins). Autocatalytic function involves DNA directing its own synthesis (replication).

AUG

AUG is the universal initiation codon that codes for methionine and starts protein synthesis in all organisms. UAA, UAG, and UGA are stop codons that terminate protein synthesis.

Inducer inactivates repressor

When lactose is present, it acts as an inducer that binds to the repressor protein, inactivating it. This allows the operon to be switched on and enzymes for lactose metabolism to be produced.