Overview
This lecture explains the process of binary fission in bacteria, highlighting its steps, comparisons with mitosis, and key cellular events involved.
Terminology and Basics
- Binary fission is the process by which most bacteria split into two identical cells.
- "Binary" means two parts; "fission" means splitting apart.
- Binary fission is analogous to mitosis but is not the same because bacteria lack a nucleus.
Differences from Mitosis
- Mitosis refers to nuclear division in eukaryotic (nucleus-containing) cells; prokaryotes like bacteria do not have a nucleus, so the process is named differently.
- The division process in bacteria is more similar to that of plant cells than animal cells in some aspects.
Steps of Binary Fission
- DNA replication: the bacterial chromosome (a single, circular DNA molecule) is copied.
- The origin of replication starts DNA duplication, allowing replication in both directions, speeding up the process.
- The cell doubles its DNA and also duplicates components like ribosomes and other cell contents.
- The cell elongates, preparing to divide into two normal-sized cells.
- DNA and cellular contents are split evenly between two groups.
- A septum (partition) forms between the two halves, leading to the physical separation of cells.
- The division of cytoplasm and cell components is called cytokinesis.
Comparison with Plant Cell Division
- Both processes involve DNA and cellular components being divided into two piles.
- In bacteria, the partition formed is called a septum; in plants, it is called a cell plate.
- Both set up a new cell wall before final separation.
Key Terms & Definitions
- Binary fission — a form of asexual reproduction where one bacterial cell divides into two identical cells.
- Mitosis — division of the nucleus in eukaryotic cells.
- Cytokinesis — the division of the cell’s cytoplasm and contents after DNA has been separated.
- Origin of replication — the specific site on bacterial DNA where replication begins.
- Septum — the new partition that forms between two dividing bacterial cells.
Action Items / Next Steps
- Review diagrams comparing binary fission in bacteria and cell division in plants.
- Be able to describe each step of binary fission.
- Study the differences between binary fission and mitosis.