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DNA and RNA (Biochemistry Exam 2)
Replication, Transcription, and Translation (Prof. Maurer - WUSTL)
Undergraduate 3

Additional Biochemistry Flashcards




Steps of Bacterial Replication
  1. Primosome formation 
  2. Gamma Complex binds to Primed Single Strand of DNA 
  3. Gamma Complex assembles beta-clamp dimer with hydrolysis of ATP 
  4. DNA polymerase associates with beta-clamp 
  5. 2 DNA polymerases are bound together by the T connecter. 
  6. DNA Synthesis
Primosome formation

(Primosome formation = Step 1 of bacterial DNA replication.)


  1. Dna A binds to OriC sequence 
    • Ori C is AT rich. AT base pair is weaker than GC. 
    • Dna A Bends and partially unwinds DNA. 
  2. Dna B (a helicase) is recruited and unwinds DNA.
    • Bidirectional bubble forms w/ 2 oppositely directed replication forks. 
    • Single-stranded DNA-binding proteins bind ssDNA to keep it single stranded. 
  3. Dna G (an RNA polymerase) is recruited by Dna B. 
    • Dna G creates the RNA primer - once in the leading strand and many times in the lagging strand.  (See Dna G flashcard for more details.)
Dna A
Enzyme that binds to the Ori sequence to initiate bacterial replication. Bends DNA by 40 degrees globally and 28 degrees locally. Partially unwinds DNA.
Dna B
Helicase that unwinds DNA during bacterial replication. Forms a bidirectional bubble with 2 oppositely directed replication forks. Recruits Dna G.
Dna G

Replication-priming RNA polymerase that adds RNA primer to the template strand during bacterial replication. Does this once in the leading strand and many times in the lagging strand. Structurally distinct from eukaryotic primases. Low processivity and fidelity. Can't distinguish between NTPs and dNTPs. Steps:


  1. Binds to single stranded DNA.
  2. Finds initiation site. (AC followed by 8 - 10 nucleotides.)
  3. 2 NTPs bind
    • 1st to initiation site 
      • "A" NTP binds opposite a T in the Ori C sequence; attacks next nucleotide (always a "C" NTP) at the elongation site.
    • 2nd to elongation site (always a C.)
  4. RNA primer synthesis is intitiated.
  5. Growing RNA is transferred to initiation site.
  6. Primer is transferred to DNA.
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