Cell cycle Archives - Laboratory Notes

Post-Translational Modifications in Cell-Cycle Regulation

admin — Mon, 31 Aug 2026 09:29:07 +0000

Post-translational modifications are essential regulators of cell-cycle progression. Learn how phosphorylation, ubiquitination, acetylation, SUMOylation, methylation, and other PTMs control CDKs, cyclins, checkpoints, DNA replication, mitosis, and protein degradation.

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Timed Proteolysis as a Molecular Engine of Cell-Cycle Progression: Key Proteins Whose Degradation Drives Cell-Cycle Transitions

admin — Sat, 22 Aug 2026 23:12:32 +0000

Timely protein degradation is essential for orderly cell-cycle progression. Explore key cell-cycle regulators, their degradation mechanisms, and how their turnover controls G1/S transition, mitosis, chromosome segregation and mitotic exit.

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Cdc25

admin — Wed, 19 Aug 2026 15:26:51 +0000

Cdc25 phosphatases activate CDKs to drive both the G1–S and G2–M transitions. By removing inhibitory phosphates from CDK1 and CDK2, Cdc25 triggers DNA replication and mitotic entry. Checkpoint kinases such as Chk1 inhibit Cdc25 during DNA damage, while Cdc25 overexpression promotes genomic instability and contributes to tumour progression.

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Retinoblastoma Protein (pRb)

admin — Wed, 19 Aug 2026 12:55:16 +0000

pRb is a major tumour‑suppressor that governs the G1–S transition by restraining E2F transcription factors and maintaining a repressive chromatin state. When pRb becomes hyperphosphorylated, cells commit to DNA replication. Loss of pRb function leads to uncontrolled proliferation, replication stress and genomic instability, making it a key player in cancer development.

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Cdh1

admin — Wed, 19 Aug 2026 11:56:08 +0000

Cdh1 is a major activator of the APC/C complex, responsible for mitotic exit, G1 maintenance and replication licensing. By degrading Cyclin B, Aurora A, Plk1 and Geminin, Cdh1 prevents premature S‑phase entry and maintains genomic stability. Its dysregulation contributes to replication stress, chromosomal instability and cancer development.

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Endoreduplication

admin — Wed, 19 Aug 2026 07:52:46 +0000

Endoreduplication is a specialised cell‑cycle variant in which cells repeatedly replicate their DNA without mitosis, producing polyploid nuclei. Driven by Cyclin E, CDK2, APC/C–Cdh1 and E2F7/8, this process enhances cell size, biosynthetic capacity and stress tolerance in plants, insects and mammalian tissues.

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Asymmetric Cell Division

admin — Wed, 19 Aug 2026 07:16:59 +0000

Asymmetric cell division produces daughter cells with different sizes, molecular compositions or developmental fates. Guided by polarity complexes, spindle orientation and unequal segregation of determinants such as Numb and Prospero, this process maintains stem‑cell pools, drives tissue development and prevents uncontrolled proliferation. Its disruption contributes to degenerative disease and cancer.

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Cell Cycle Checkpoint

admin — Tue, 18 Aug 2026 20:51:53 +0000

Cell‑cycle checkpoints act as surveillance systems that monitor DNA integrity, replication completeness and spindle attachment. The G1, G2 and spindle checkpoints prevent cells with damage or misaligned chromosomes from dividing, ensuring accurate genome transmission and protecting against genomic instability and cancer.

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Cell Cycle Genes

admin — Tue, 18 Aug 2026 18:40:49 +0000

Cell‑cycle genes coordinate the progression of G1, S, G2, and M phases through cyclins, CDKs, checkpoints, and replication machinery. Their precise regulation ensures accurate DNA duplication, faithful chromosome segregation, and controlled cell proliferation. Understanding these genes is essential for explaining genomic stability and the molecular basis of cancer.

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G1/S transition

admin — Tue, 18 Aug 2026 18:18:41 +0000

The G1/S transition is the critical checkpoint where a cell commits to DNA replication. It integrates cyclin–CDK activity, Rb phosphorylation, and E2F activation to ensure accurate S‑phase entry. Proper regulation protects genomic stability and prevents uncontrolled proliferation.

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Embryonic Cleavage Cycle

admin — Tue, 18 Aug 2026 11:44:17 +0000

Embryonic cleavage cycles transform a single‑celled zygote into a multicellular embryo through rapid, synchronous divisions. This article explains cleavage patterns, maternal control, and the mid‑blastula transition.

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Binary Fission

admin — Tue, 18 Aug 2026 09:04:06 +0000

Binary fission is a rapid and efficient form of asexual reproduction in prokaryotes. It involves DNA replication, chromosome segregation, and septum formation, resulting in two identical daughter cells.

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Cell Cycle: Concepts, Contexts, and Terminology

admin — Tue, 18 Aug 2026 08:09:34 +0000

Reliability Index *****Note: We welcome your feedback. If you notice any errors, inconsistencies, or have suggestions for improvement, please share...

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S Phase (Cell Cycle)

admin — Mon, 17 Aug 2026 10:07:19 +0000

The S phase is the period of the cell cycle in which DNA is replicated, producing identical copies of the genome for distribution to daughter cells. It is tightly regulated to maintain accuracy and prevent genomic instability.

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G₂ Phase (Cell Cycle)

admin — Sun, 16 Aug 2026 11:51:03 +0000

The G₂ phase is the period after DNA replication during which the cell checks for errors, repairs damage, and prepares for mitosis. It is essential for accurate chromosome segregation and genomic stability.

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Terminally Differentiated Cell

admin — Sun, 16 Aug 2026 09:45:08 +0000

Terminally differentiated cells are highly specialized cells that have undergone a differentiation program and generally withdraw permanently from productive cell division. This article explains the molecular mechanisms of terminal differentiation, its relationship with cell-cycle exit, and the differences between terminal differentiation, quiescence, and cellular senescence.

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Cellular Quiescence

admin — Sun, 16 Aug 2026 09:06:51 +0000

Cellular quiescence is a reversible non-proliferative state in which cells temporarily withdraw from the active cell cycle while remaining viable and metabolically active. This article explores the molecular mechanisms regulating quiescence, its relationship with the G₀ phase, cell-cycle re-entry, stem-cell maintenance, metabolism, transcription, and cellular quality control, as well as its distinction from senescence and terminal differentiation.

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Ubiquitin-Proteasome System in Cell Cycle Regulation

admin — Fri, 14 Aug 2026 15:36:16 +0000

The ubiquitin-proteasome system is the master regulator of the cell cycle, controlling cyclin degradation, checkpoint progression, and mitotic exit. This comprehensive guide covers UPS mechanisms in G1/S transition, S phase, mitosis, and cancer therapy.

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G0 phase

admin — Thu, 24 Aug 2023 09:38:30 +0000

The G0 phase is a reversible state of cellular dormancy where cells exit the cell cycle. Discover how quiescence protects stem cells, its role in aging, and the mechanisms that regulate this vital cellular state.

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Anaphase-Promoting Complex/Cyclosome (APC/C)

admin — Wed, 19 Jul 2023 07:54:17 +0000

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