Replication in Living Cells Prokaryotes Eukaryotes Both 1. New chromosomes remain attached to cell membrane 2. Proteins check for errors 3. Starts at one place 4. Proceeds in two directions 5. Copies of DNA condense into chromosomes that separate 6. Starts at many places
The correct answer and explanation is:
Here’s the completed chart with correct placement of each statement under Prokaryotes, Eukaryotes, or Both:
| Statement | Prokaryotes | Eukaryotes | Both |
|---|---|---|---|
| 1. New chromosomes remain attached to cell membrane | ✓ | ||
| 2. Proteins check for errors | ✓ | ||
| 3. Starts at one place | ✓ | ||
| 4. Proceeds in two directions | ✓ | ||
| 5. Copies of DNA condense into chromosomes that separate | ✓ | ||
| 6. Starts at many places | ✓ |
Explanation (300 words):
DNA replication is a critical process in all living cells, ensuring that genetic material is accurately passed to daughter cells. While the fundamental process is similar across domains of life, there are key differences between prokaryotes and eukaryotes due to structural and organizational differences in their cells.
Prokaryotes, such as bacteria, have a single circular chromosome. Replication typically begins at one origin of replication and proceeds in two directions around the circle, allowing for efficient duplication. A notable characteristic in prokaryotes is that newly replicated chromosomes remain attached to the cell membrane, which assists in segregating DNA during cell division. Since their genome is small and simple, prokaryotes manage with a single origin and fewer regulatory checkpoints.
Eukaryotes, which include plants, animals, and fungi, have multiple linear chromosomes housed in a nucleus. Because of their larger genome size, replication must be more complex and efficient. Replication starts at many places along each chromosome to ensure the entire genome is copied in a reasonable amount of time. After DNA is copied, it condenses into visible chromosomes, which then line up and are pulled apart during mitosis. This condensation is crucial for accurate segregation.
Both prokaryotes and eukaryotes utilize proteins to check for errors during replication. These include proofreading enzymes like DNA polymerase, which can remove and correct mismatched nucleotides, helping to ensure genetic fidelity. Also, in both domains, DNA replication proceeds in two directions from each origin (bidirectional replication), forming replication forks that move outward.
Understanding the similarities and differences in replication mechanisms across cell types helps illustrate how evolution shaped DNA handling to fit the specific needs of simple versus complex organisms.