Covers the phases of the cell cycle, from G1 through S, G2 and mitosis to the quiescent G0 state, then the key regulators: cyclins, cyclin-dependent kinases and their inhibitors, grouped into INK4 and CIP/KIP families. It goes on to the G1/S, G2/M and spindle assembly checkpoints, the role of p53 in DNA damage response, and how disturbances lead to cancer, arrest or apoptosis. It closes with clinical points on CDK inhibitors, genetic disorders and cyclin-based biomarkers.
Topic 59 of 70 in the MU Sofia syllabus for Biochemistry (Dental Medicine, Year 2). The free AceMed note covers it in 7 sections, about 549 words (4 min of reading), with 10 flashcards.
In this note
Molecular Mechanisms of Cell Cycle Regulation
Key Regulators of the Cell Cycle
Checkpoints in the Cell Cycle
Molecular Mechanisms
Disturbances in Cell Cycle Regulation
Clinical Significance
Summary
Molecular Mechanisms of Cell Cycle Regulation
Overview of the Cell Cycle
Definition: The cell cycle is a series of stages through which a cell passes to divide and produce two daughter cells.
Phases:
G1 Phase (Gap 1): Cell growth and preparation for DNA synthesis.
S Phase (Synthesis): DNA replication.
G2 Phase (Gap 2): Further growth and preparation for mitosis.
M Phase (Mitosis): Division of the nucleus and cytoplasm to form two daughter cells.
G0 Phase: A quiescent state where cells exit the cycle and do not divide.
Key Regulators of the Cell Cycle
Cyclins:
Function: Regulatory proteins whose levels fluctuate throughout the cell cycle.
Types: Cyclins D, E, A, and B, each associated with different cell cycle phases.
Cyclin-Dependent Kinases (CDKs):
Function: Enzymes that, when activated by binding to cyclins, phosphorylate target proteins to drive cell cycle progression.
Regulation: Controlled by the presence of cyclins, phosphorylation, and CDK inhibitors (CKIs).
CDK Inhibitors (CKIs):
Function: Proteins that bind to and inhibit the activity of cyclin-CDK complexes.
Types: Two main families – INK4 (e.g., p16) and CIP/KIP (e.g., p21, p27).
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