Related Experiment Video
Updated: Jul 17, 2026
14:27
A Cell-Free Assay Using Xenopus laevis Embryo Extracts to Study Mechanisms of Nuclear Size Regulation
Published on: August 8, 2016
Cell size regulation in mammalian cells
Pedro Echave1, Ian J Conlon, Alison C Lloyd
1MRC Laboratory for Molecular Cell Biology and Department of Biochemistry, University College London, London, UK.
Cell Cycle (Georgetown, Tex.)
|January 25, 2007
Summary
Mammalian cells do not have a "cell-size checkpoint" to regulate division. Cell proliferation rate is independent of cell size, influenced by growth factors and mitogens.
Area of Science:
- Cell Biology
- Developmental Biology
- Physiology
Background:
- Cell growth and proliferation are crucial for animal development and homeostasis.
- The coordination between cell growth and cell cycle progression is not fully understood.
- The existence of cell-size checkpoints in mammalian cells remains controversial.
Purpose of the Study:
- To investigate the role of cell-size checkpoints in mammalian cell proliferation.
- To determine if cell size or mass influences the rate of cell division.
- To examine the impact of extracellular factors and culture conditions on cell size and proliferation.
Main Methods:
- Analysis of primary mammalian cell proliferation rates.
- Assessment of cell size and mass in relation to cell cycle progression.
- Comparison of in vitro cultured cells with in vivo cell characteristics.
Main Results:
- Primary mammalian cells proliferate at rates independent of their size or mass.
- Cell size is primarily determined by the balance of extracellular growth factors and mitogens.
- Common culture conditions lead to significantly larger cell sizes (300-500%) compared to in vivo conditions.
Conclusions:
- Evidence suggests the absence of a functional cell-size checkpoint in mammalian cells.
- Cell proliferation is regulated by external factors rather than intrinsic size.
- Current cell culture methods can significantly alter cell size, impacting cell behavior.
Related Concept Videos
02:36Cells Coordinate Growth and Proliferation
Cell size is a significant factor impacting cellular design, function, and fitness. There exists some internal coordination by which cells double their masses before division, thus, achieving homeostasis. Coordination between cell growth and proliferation depends on the checkpoints in between cell cycle phases. Loss of coordination or failure in the checkpoint mechanism can drive the cell to uncontrolled growth and loss of cellular function. Like dividing cells that coordinate cellular growth,...
01:22Cell Size
Cell sizes vary widely among and within organisms. Bacterial cells range between 1-10 micrometers (μm)and are considerably smaller than most eukaryotic cells. The smallest bacteria are 0.1 μm in diameter—about a thousand times smaller than eukaryotic cells, which typically range from 10-100 μm.Surface AreaCells can take in nutrients and water via diffusion through the plasma membrane itself or through specific channels in the membrane. The area of the membrane surrounding the cells limits the...
01:45Positive Regulator Molecules
To consistently produce healthy cells, the cell cycle—the process that generates daughter cells—must be precisely regulated.
02:39Positive Regulator Molecules
Mitotic cell division results in daughter cells that exactly resemble the parent cell. However, errors in the DNA replication or distribution of genetic material may lead to genetic mutations that may be passed down to every new cell formed from the resulting abnormal cell. Propagation of such mutant cells is restricted through checkpoint mechanisms present at different stages of the cell cycle. These checkpoints involve regulator molecules that either promote or demote cell cycle events.
01:22Enlargement of the Plasma Membrane
Cell division and enlargement are processes that require precise control. The control ensures that cell division cannot proceed unless the cell has grown to a specific size. A spherical, dividing cell requires an approximately 1.6X increase in its surface area to double its volume. The secretory pathway also has a significant role in cell membrane enlargement. Secretory vesicles that bud off from the Golgi apparatus and later fuse with the plasma membrane during exocytosis are a major source of...
01:28The Cell Cycle Control System
The cell cycle regulation directs how a cell proceeds from one phase to the next and begins mitosis. The cell cycle control system includes intracellular regulatory molecules and external triggers. They provide "stop" or "advance" signals and operate at specific cell cycle stages termed checkpoints to ensure that a particular process is completed before the cell advances to the next phase.
Cyclins and cyclin-dependent kinases (Cdks) are the primary cell cycle regulators and function at the cell...
Cyclins and cyclin-dependent kinases (Cdks) are the primary cell cycle regulators and function at the cell...