DNA Structure and Function: Key Concepts Flashcards
What is DNA melting?
The process where double-stranded DNA separates into single strands when heated, occurring at a specific melting temperature (Tm).
Why is DNA melting important for PCR?
It enables strand separation in the denaturation step, allowing primers to anneal and DNA synthesis to occur during amplification.
What is tautomerization of DNA bases?
A process where bases shift between common (keto/amino) and rare (enol/imino) forms, potentially causing mismatched base pairing.
How does tautomerization affect DNA replication?
Rare tautomers can pair incorrectly, leading to replication errors and mutations.
What was Griffith’s experiment?
Demonstrated the “transforming principle” where heat-killed virulent bacteria transformed non-virulent bacteria into virulent ones.
How did the Hershey-Chase experiment prove DNA’s role in heredity?
Showed that only DNA (not protein) from bacteriophages entered bacterial cells to direct replication.
What must be removed from eukaryotic genes before expressing them in E. coli?
Introns, as E. coli cannot process them; cDNA is used instead.
Why is codon optimization important for expressing eukaryotic genes in E. coli?
To match E. coli’s preferred codon usage and improve translation efficiency.
What is the purpose of an inducible promoter in E. coli expression systems?
To control when the eukaryotic gene is transcribed, e.g., using IPTG to activate the lac promoter.
