The cell cycle describes how a cell grows, copies its DNA, and prepares to divide. Understanding its phases and chromosome organization explains how body cells replace worn-out cells while preserving genetic information.
A somatic cell is a body cell other than a cell that produces eggs or sperm. Cells that produce eggs and sperm are germ cells. Most somatic cells divide at some point during life, although some cells—such as mature red blood cells and most neurons—do not normally divide.
All flashcards
What happens during G₁, S, and G₂?
In G₁ the cell grows and performs normal functions; in S it replicates its DNA; in G₂ it prepares for mitosis.
How do mitosis and cytokinesis differ?
Mitosis divides the nucleus and distributes genetic material; cytokinesis divides the cytoplasm and cell body.
How do cyclins and cyclin-dependent kinases (CDKs) regulate the cell cycle?
They work with other molecules to regulate whether a cell passes checkpoints and progresses through the cycle.
How can a proto-oncogene contribute to cancer?
If altered to become overactive, a proto-oncogene can become an oncogene that drives inappropriate cell division.
How do benign and malignant tumors differ?
Malignant tumors can damage surrounding tissues and may spread; benign tumors do not pose this threat.
Quiz questions
What role do kinetochores play during mitosis?Answer: They provide sites where spindle microtubules attach to chromosomes.
What does the metaphase checkpoint verify before chromosome separation begins?Answer: That chromosomes are aligned and sister chromatids are attached to spindle microtubules.
What happens to sister chromatids during anaphase?Answer: They separate and move toward opposite ends of the cell.
Which structure pinches an animal cell's cytoplasm during cytokinesis?Answer: A contractile band of actin microfilaments forming a cleavage furrow.
What is a typical role of tumor suppressor genes?Answer: They can restrain division, respond to DNA damage, or promote cell death.
Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.