Understanding the Impact of Radioactive Thymine on E. coli Cell Division

What would be the result if radioactive thymine was added to an actively dividing culture of E. coli bacteria?

• A. Only the original cell would be radioactive
• B. Only one daughter cell would be radioactive
• C. DNA in both daughter cells would be radioactive
• D. DNA would not be affected by radioactive thymine

Answer: (C)

When radioactive thymine is introduced to an actively dividing culture of E. coli bacteria, it becomes incorporated into the DNA during DNA replication. E. coli, like all living organisms, utilizes thymine, one of the four nucleotides that comprise DNA. During cell division, specifically during the S phase of the cell cycle, the DNA is replicated so that each daughter cell receives a complete copy of the genetic material. Since thymine is a key component of DNA, the introduction of radioactive thymine means that during replication, E. coli will synthesize new DNA strands incorporating the radioactive version of thymine in place of the non-radioactive form. Consequently, both daughter cells, which arise from the division of the parent cell, will contain DNA that has incorporated the radioactive thymine. Therefore, when the E. coli completes its cell division, both daughter cells will have DNA that is radioactive, as they each receive one copy of the parent’s DNA that includes the radioactive thymine. This demonstrates how the genetic material is passed on during cellular division and highlights the significance of nucleotide incorporation in replication processes.

When it comes to the impact of radioactive materials on living organisms, you'd be surprised at how a single component can modify an entire process. Take radioactive thymine and E. coli as an example. Now, you might be wondering: what happens when you throw radioactive thymine into a pool of these rapidly dividing bacteria? Well, let me explain!

To kick things off, E. coli, like every living organism, has to create new cells to survive, and they do this through cell division. Picture this process like a well-choreographed dance—each move is crucial, and timing is everything. The S phase of the cell cycle is particularly critical, as this is when DNA replication occurs. During this phase, the bacteria replicate their DNA, ensuring that each new daughter cell receives a complete set of genetic information.

Now, here comes the twist. When radioactive thymine is added to these cultures, E. coli will naturally incorporate that into its DNA while copying it. Yup, you heard that right. Just like a chef needing flour to whip up a perfect cake, E. coli requires thymine to bake its genetic recipe! And lo and behold, after the dance of division, both daughter cells are now sporting that radioactive touch in their DNA.

This raises an interesting point: wouldn’t you agree it’s fascinating how biological systems are so finely tuned? They adapt to incorporate what’s available. In our case, those clever little bacteria are not picky—the radioactive thymine slides right into their genetic makeup. So, both daughter cells end up with DNA rich in radioactive thymine after the division is complete.

But why does this matter? Well, understanding how nucleotides incorporate into DNA sheds light on important biological processes, such as replication and mutation. Think about it: this knowledge helps in everything from medical research to biotechnology developments. It’s like having a backstage pass to the inner workings of life itself!

In summary, the addition of radioactive thymine to an actively diving culture of E. coli results in DNA from both daughter cells becoming radioactive, demonstrating the elegance and precision of DNA replication. So, next time you think about the mechanics of life, remind yourself of how even a single radioactive molecule can illustrate such a profound concept! This intricate relationship between thymine and DNA lays the groundwork for understanding more complex genetic phenomena.