Summarize the similarities and differences in rolling-circle replication, theta replication, and linear eukaryotic replication.

Rolling-circle replication, theta replication, and linear eukaryotic replication are all methods of DNA replication, but they have some key differences.

Similarities:
- All three methods involve the synthesis of new DNA strands based on a template strand.
- They all require the use of enzymes such as DNA polymerase to catalyze the replication process.
- The end result of all three methods is the production of two identical DNA molecules from one original molecule.

Differences:
- Rolling-circle replication is a method commonly used by some viruses and plasmids, where a single strand of DNA is used as a template to produce multiple copies of a circular DNA molecule.
- Theta replication is a method commonly used by bacteria, where the circular DNA molecule forms a "theta" structure and replication occurs bidirectionally from a single origin of replication.
- Linear eukaryotic replication occurs in eukaryotic cells, where the DNA is organized into linear chromosomes. Replication occurs bidirectionally from multiple origins of replication, and the ends of the chromosomes are protected by telomeres.

In summary, while all three methods involve DNA replication, they differ in the structure of the DNA molecule being replicated and the specific mechanisms involved in the replication process.