Dna Replication Transcription And Translation

Understanding DNA replication:

DNA replication is semi-conservative: each new DNA molecule contains one original strand and one newly synthesized strand.

Tracking through replications:

Initial state:

• 1 DNA molecule with both strands radioactive (let's call them R-R)

After 1st replication:

• Original strands separate
• Each pairs with a new non-radioactive strand (N)
• Result: 2 DNA molecules, both hybrid (R-N)

After 2nd replication:

• The 2 hybrid molecules (R-N) replicate
• Each R-N produces:
  • 1 hybrid molecule (R-N)
  • 1 non-radioactive molecule (N-N)
• Result: 4 DNA molecules total
  • 2 with radioactive strand (R-N)
  • 2 without radioactive strand (N-N)

After 3rd replication:

• The 2 hybrid (R-N) and 2 non-radioactive (N-N) molecules replicate
• From 2 hybrid (R-N):
  • Each produces 1 hybrid (R-N) and 1 non-radioactive (N-N)
  • Total: 2 hybrid (R-N) + 2 non-radioactive (N-N)
• From 2 non-radioactive (N-N):
  • Each produces 2 non-radioactive (N-N)
  • Total: 4 non-radioactive (N-N)
• Result: 8 DNA molecules total
  • 2 with radioactive thymidine (R-N)
  • 6 without radioactive thymidine (N-N)

Answer: 2

The goal is to determine the time required for the synthesis of an mRNA for a protein with a molecular weight of 110 kDa in a bacterium with a transcription rate of 50 nucleotides/min.

1. First, calculate the number of amino acids present in the protein. Given the protein's molecular weight is 110 kDa and the average molecular weight of an amino acid is 110 Da, the number of amino acids is: .

2. The mRNA will require codons for each amino acid. Each codon consists of 3 nucleotides, so the total number of nucleotides required for 1,000 amino acids is: .

3. Assuming no additional sequences, the mRNA transcript is simply the number of nucleotides that need to be synthesized, which is 3,000 nucleotides.

4. Given the transcription rate is 50 nucleotides/min, the time needed to transcribe 3,000 nucleotides is: .

5. Confirming the range provided: The calculated time (60 min) falls within the expected range of 60 to 60. Hence, the solution is correct and verified.

Therefore, the time taken for synthesis of the mRNA is 60.0 min.

In transcription, adenine in the DNA template pairs with uracil in RNA. Since adenine’s mole fraction in DNA is 0.16, uracil’s mole fraction in RNA will also be 0.16.