Cancer includes many diseases that share a central feature: uncontrolled cell division. This lesson explains how errors in DNA can disrupt cell-cycle control and how changes to proto-oncogenes may speed cell-cycle progression.
The cell cycle is governed by overlapping controls and checkpoints. One important checkpoint process monitors whether DNA has been properly replicated during the S phase. These safeguards reduce the chance that damaged or incorrectly copied DNA will be passed to daughter cells, but they cannot eliminate every error.
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What is a gene mutation?
A gene mutation is a change in the DNA nucleotide sequence within a gene. It may affect the protein produced from that gene.
What is the role of cell-cycle checkpoint surveillance during S phase?
It monitors important conditions, including proper DNA replication, helping limit the passage of replication errors to daughter cells.
How can mutations accumulate in a dividing cell population?
If a mutated cell continues dividing, it can pass its DNA changes to daughter cells. Further errors may occur and be inherited in later generations.
How are proto-oncogenes and oncogenes related?
Proto-oncogenes are normal genes that promote cell-cycle progression. When altered to increase cell-cycle activity, they are called oncogenes.
How might early activation of Cdk affect a cell?
It may push the cell past a checkpoint before all required conditions are met. If the resulting cells keep dividing, they may acquire additional mutations.
Quiz questions
What shared feature characterizes the diseases collectively called cancer?Answer: Uncontrolled cell division.
What is a tumor in the context of abnormal cell growth?Answer: A mass of cells resulting from cell growth.
What effect did inhibiting folic acid uptake by tumor cells have in early research?Answer: It reduced tumor-cell growth.
Jane C. Wright identified methotrexate as an effective treatment for which cancers?Answer: Breast and skin cancers.
Based on Concepts of Biology by Samantha Fowler, Rebecca Roush, James Wise (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.