Cell Biology

Cell division is the process that lets one parent cell split into two or more daughter cells. In single-celled organisms, it serves as a way to reproduce. In multicellular organisms, it helps with growth, development, and tissue repair.

Cell division also makes reproductive cells, including sperm and eggs. Because this process is tightly regulated, errors in cell division can lead to disease. Cancer is one major example of what can happen when cell division goes wrong.

JoVE's Cell Division...

Cell cycle analysis tracks how DNA levels change as a cell grows, copies its genome, and divides into two daughter cells by mitosis. These DNA shifts let scientists sort cells by the phase of the cell cycle they are in, based on DNA content.

The method in this page uses DNA staining to measure those changes. It includes bromodeoxyuridine, or BrdU, which is a thymidine analog that becomes part of newly made DNA strands, and propidium iodide, or PI, which stains all DNA. Together, these dyes...

Mitosis is the process of cell division that splits a cell’s genetic material equally into two daughter cells. It moves through six phases, and each phase has its own visible changes in the chromosomes and other cell parts. Fluorescence live cell imaging lets scientists watch these changes in real time.

This approach gives a closer look at how mitosis is controlled and how it can fail. That matters in cell biology and in diseases such as cancer. The page also explains key points for getting a...

Cell motility and migration help cells move during normal growth and in disease. During development, cell movement helps build complex tissues and organs. The same movement process can also be used by tumor cells. When that happens, cancer cells spread in a process called metastasis.

A key part of cell movement is the actomyosin system. Actomyosin is an internal network made of actin and myosin molecules. Together, these proteins create contractile force that can pull a cell in different...

Cell movement can be measured with a Boyden chamber, also called a transwell migration assay. Scientists use this setup to study how cells respond to chemical cues during development, immunity, and disease states such as cancer.

The chamber uses an insert that separates the wells of a multiwell plate into top and bottom compartments. The cells being tested are placed in the top compartment. A chemoattractant, which is a chemical signal that draws cells toward it, is placed in the bottom...

The extracellular matrix (ECM) is a network of molecules that gives cells and tissues structural support and helps cells communicate with one another. Three-dimensional cell culture methods let scientists study this environment more closely in the lab. They are useful because they better model how cells behave in living tissue.

Cell movement through a 3D matrix is similar to movement across a flat 2D surface in some ways. Cells still need to attach and move forward. But in the ECM, they also...

Cells move materials in and out of the cell by endocytosis and exocytosis. Endocytosis brings substances in from the extracellular environment, while exocytosis releases molecules to the outside. Both processes use vesicles, which are lipid membrane-bound sacs.

These membrane transport steps are important for normal cell physiology. They also matter when the process goes wrong and disease states develop. Understanding the molecular architecture and mechanisms of endocytosis and exocytosis...

Cell-surface biotinylation assay is a method for tracking membrane proteins that move inside a cell through endocytosis. Endocytosis is the process cells use to take proteins from the membrane into the cytoplasm. Once inside, those proteins may be broken down or returned to the membrane by recycling.

This assay uses a biotin derivative, a small chemical tag related to biotin, to label proteins on the cell surface. The tag can then be chemically cleaved away from proteins that stay exposed on...

FM dyes are fluorescent molecules used to track vesicle recycling in cells. They help scientists follow how membrane vesicles are taken up and then returned to the cell surface. Because of these properties, FM dyes are useful tools for studying vesicle activity.

These dyes insert into the outer leaflet of phospholipid bilayer membranes. After membrane insertion, they enter the cell through endocytosed vesicles. When those vesicles recycle back to the membrane, the dyes are released.

FM dyes...

Cell metabolism includes the reactions that help cells build molecules and break them down. In anabolic reactions, cells join small units such as amino acids or nucleotides to make larger molecules. In catabolic reactions, cells break molecules into smaller components.

These reactions depend on energy, which cells often use or release as ATP, a high-energy molecule. ATP helps power the chemical changes that keep cells active and growing. Together, anabolic and catabolic reactions are the core...

ATP levels and cell viability can be measured with a bioluminescence assay. The method uses the firefly luciferase-luciferin reaction, which produces light when luciferase converts luciferin into oxyluciferin. That reaction needs energy from ATP to proceed, so the light signal can be used to estimate ATP in cells.

ATP is the cell’s energy currency, so its level can reflect cellular metabolism and overall cell health. This page explains how glucose metabolism during cellular respiration leads...

Reactive oxygen species, or ROS, are oxygen-derived molecules that can oxidize other molecules in cells. They are chemically active, and when ROS build up without control, they can damage DNA and other biological molecules. At the same time, ROS can also act in normal signaling inside the body.

Research on ROS links these molecules to metabolism and disease. Studies also show that ROS can help activate transcription factors, which are proteins that control gene activity. They can also take...

Cells can die in several ways, including necrosis, apoptosis, and autophagic cell death. These pathways can be triggered by cell injury, low nutrient levels, or signaling proteins. They help scientists understand how cells respond to stress and damage.

Necrosis is often described as an accidental form of cell death. By contrast, evidence suggests that apoptosis and autophagy are programmed, or planned, processes controlled by the cell. Researchers study these pathways to see how they differ...

TUNEL staining helps detect apoptotic cells by marking fragmented DNA. Apoptosis is a form of programmed cell death, and one of its key signs is nuclear DNA fragmentation by nucleases. These enzymes are activated by caspases, the proteins that carry out the cell death program.

The assay uses terminal deoxynucleotidyl transferase, an enzyme that adds dUTP nucleotides to the free 3' ends of broken DNA. The dUTPs carry chemical tags that can produce fluorescence or color. This makes apoptotic...

Annexin V and propidium iodide (PI) staining helps identify how cells are dying. The method is used to tell apoptosis from necrosis. It does this by tracking two signals that change as a cell dies.

Annexin V is a protein that binds phosphatidylserine, a phospholipid that normally stays on the inner side of the cell membrane. During the early stages of apoptosis, phosphatidylserine flips to the outer membrane leaflet. PI is a DNA-binding dye that can enter cells only when the membrane is...