The Cell Cycle and Mitosis
This lesson connects molecular mechanisms, cell behavior and biological evidence. Instead of memorizing isolated terms, follow what changes, what is measured, where the process occurs and why the outcome matters to a living system.
Big idea
During G1 a cell grows, during S phase DNA is replicated, and during G2 the cell prepares for division. Checkpoints monitor size, DNA integrity, replication and chromosome attachment before progression.
Learning goals
- Interphase: During G1 a cell grows, during S phase DNA is replicated, and during G2 the cell prepares for division.
- Cell-cycle checkpoints: Checkpoints monitor size, DNA integrity, replication and chromosome attachment before progression.
- Mitosis: Prophase, metaphase, anaphase and telophase distribute duplicated chromosomes into two nuclei.
- Cytokinesis: Cytokinesis divides the cytoplasm after nuclear division, producing two daughter cells.
- Growth control: Regulatory proteins and external signals coordinate division; failures can lead to uncontrolled proliferation.
Core concepts
1. Interphase
During G1 a cell grows, during S phase DNA is replicated, and during G2 the cell prepares for division.
Observation or application: A cell doubles its DNA before chromosomes are separated.
2. Cell-cycle checkpoints
Checkpoints monitor size, DNA integrity, replication and chromosome attachment before progression.
Observation or application: A cell with damaged DNA pauses for repair rather than entering mitosis immediately.