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October, 2006
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Cells: The fundamental, structural, and functional units or subunits of living organisms. They are composed of Cytoplasm containing various Organelles and a Cell membrane boundary.

Transformation of E. coli Cells Using an Adapted Calcium Chloride Procedure

JoVE 10515

Source: Natalia Martin1, Andrew J. Van Alst1, Rhiannon M. LeVeque1, and Victor J. DiRita1
1 Department of Microbiology and Molecular Genetics, Michigan State University

Bacteria have the ability to exchange genetic material (DeoxyriboNucleic Acid, DNA) in a process known as horizontal gene transfer. Incorporating exogenous DNA…


Adult Stem Cells

JoVE 10810

Stem cells are undifferentiated cells that divide and produce more stem cells or progenitor cells that differentiate into mature, specialized cell types. All the cells in the body are generated from stem cells in the early embryo, but small populations of stem cells are also present in many adult tissues including the bone marrow, brain, skin, and gut. These adult stem cells typically produce the various cell types found in that tissue—to replace cells that are damaged or to continuously renew the tissue. The epithelium lining the small intestine is continuously renewed by adult stem cells. It is the most rapidly replaced tissue in the human body, with most cells being replaced within 3-5 days. The intestinal epithelium consists of thousands of villi that protrude into the interior of the small intestine—increasing its surface area to aid in the absorption of nutrients. Intestinal stem cells are located at the base of invaginations called crypts that lie between the villi. They divide to produce new stem cells, as well as daughter cells (called transit amplifying cells) that divide rapidly, move up the villi and differentiate into all the cell types in the intestinal epithelium, including absorptive, goblet, enteroendocrine, and Paneth cells. These mature cells continue to move up the villi as they carry out their functions, except Paneth cell

 Core: Biology

Glial Cells

JoVE 10843

Glial cells are one of the two main types of cells in the nervous system. Glia cells comprise astrocytes, oligodendrocytes, microglia, and ependymal cells in the central nervous system, and satellite and Schwann cells in the peripheral nervous system. These cells do not communicate via electrical signals like neurons do, but they contribute to virtually every other aspect of nervous system function. In humans, the number of glial cells is roughly equal to the number of neurons in the brain. Glia in the central nervous system (CNS) include astrocytes, oligodendrocytes, microglia, and ependymal cells. Astrocytes are the most abundant type of glial cell and are found in organized, non-overlapping patterns throughout the brain, where they closely associate with neurons and capillaries. Astrocytes play numerous roles in brain function, including regulating blood flow and metabolic processes, synaptic ion and pH homeostasis, and blood-brain barrier maintenance. Another specialized glial cell, the oligodendrocyte, forms the myelin sheath that surrounds neuronal axons in the CNS. Oligodendrocytes extend long cellular processes that wrap around axons multiple times to form this coating. Myelin sheath is required for proper conduction of neuronal signaling and greatly increases the speed at which these messages travel. Microglia—known as the macrop

 Core: Biology

Induced Pluripotent Stem Cells

JoVE 10812

Stem cells are undifferentiated cells that divide and produce different types of cells. Ordinarily, cells that have differentiated into a specific cell type are post-mitotic—that is, they no longer divide. However, scientists have found a way to reprogram these mature cells so that they “de-differentiate” and return to an unspecialized, proliferative state. These cells are also pluripotent like embryonic stem cells—able to produce all cell types—and are therefore called induced pluripotent stem cells (iPSCs). iPSCs are potentially valuable in medicine, because a patient who needs a particular cell type—for instance, someone with a damaged retina due to macular degeneration—could receive a transplant of the required cells, generated from another cell type in their own body. This is called autologous transplantation, and it reduces the risk of transplant rejection that can occur when tissues are transplanted between individuals. To create iPSCs, mature cells such as skin fibroblasts or blood cells from a person are grown in culture. Then, genes for multiple transcription factors are delivered into the cells using a viral vector, and the transcription factor proteins are expressed using the cell’s machinery. The transcription factors then turn on many other genes that are expressed by embryonic stem cells, re

 Core: Biology

Plant Cells and Tissues

JoVE 11091

Plant tissues are collections of similar cells performing related functions. Different plant tissues will have their own specialized roles and can be combined with other tissues to form organs such as flowers, fruit, stem, and leaves. Two major types of plant tissue include meristematic and permanent tissue.

Meristematic tissue, the primary growth tissue in plants, is capable of self-renewal and indefinite cell division. Every cell in the plant originates from a meristem. Meristematic tissue is classified into one of three types depending on its location inside the plant - apical, lateral, and intercalary. Apical meristems are meristematic tissue located at the tip of root and stem, which enable elongation of plant length. Lateral meristems are present in the radial portion of the stem and root and increase the thickness or girth of the maturing plant. Intercalary meristems occur only in monocots at the base of the internode and leaf blade. The intercalary meristems increase the length of the leaf blade. Permanent plant tissues are either simple (composed of similar types of cells) or complex (consisting of different kinds of cells). For example, dermal tissue is a simple permanent tissue that forms the outer protective covering. It protects the plant from physical damage and enables gas exchange. In non-woody plants, the dermal tissue is a layer of t

 Core: Biology

Embryonic Stem Cells

JoVE 10811

Embryonic stem (ES) cells are undifferentiated pluripotent cells, meaning they can produce any cell type in the body. This gives them tremendous potential in science and medicine since they can generate specific cell types for use in research or to replace body cells lost due to damage or disease.

ES cells are present in the inner cell mass of an embryo at the blastocyst stage, which occurs at about 3–5 days after fertilization in humans before the embryo is implanted in the uterus. Human ES cells are usually derived from donated embryos left over from the in vitro fertilization (IVF) process. The cells are collected and grown in culture, where they can divide indefinitely—creating ES cell lines. Under certain conditions, ES cells can differentiate—either spontaneously into a variety of cell types, or in a directed fashion to produce desired cell types. Scientists can control which cell types are generated by manipulating the culture conditions—such as changing the surface of the culture dish or adding specific growth factors to the culture medium—as well as by genetically modifying the cells. Through these methods, researchers have been able to generate many specific cell types from ES cells, including blood, nerve, heart, bone, liver, and pancreas cells. Regenerative medicine concerns the creation of living, functio

 Core: Biology

What are Cells?

JoVE 10687

Cells are the foundational level of organization of life. An organism may be unicellular, as with prokaryotes and most eukaryotic protists, or multicellular where the functions of an organism are divided into different collections of specialized cells. In multicellular eukaryotes, cells are the building blocks of complex structures and can have various forms and functions.

Cells are the building blocks of all living organisms, whether it is a single cell that forms the entire organism (e.g., a bacterium) or trillions of them (e.g., humans). No matter what organism a cell is a part of, they share specific characteristics. A living cell has a plasma membrane, a bilayer of lipids, which separates the watery solution inside the cell, also called cytoplasm, from the outside of the cell. Furthermore, a living cell can replicate itself, which requires that it possess genetic information encoded in DNA. DNA can be localized to a particular area of the cell, as in the nucleoid of a prokaryotic cell, or it can be contained inside another membrane, such as the nucleus of eukaryotes. Eukaryote means "true nucleus." The word prokaryote, hence, implies that the cell is from a group which arose before membrane-bound nuclei appeared in the history of life. Prokaryotic cells lack internal membranes. In contrast, eukaryotes have internal membran

 Core: Biology

Using a Hemacytometer to Count Cells

JoVE 5048

Many biomedical experiments require manipulation of a known quantity of cells, in order to achieve accurate, reproducible, and statistically-relevant data. Therefore, learning how to count cells is a particularly essential technique for any successful biomedical scientist. The most common way to count cells is by using a hemacytometer - an instrument that bears two laser-etched grids, which…

 Basic Methods in Cellular and Molecular Biology

Galvanic Cells- Concept

JoVE 11177


Electrochemistry is a branch of chemistry that studies the relationship between electrical energy and a chemical change. These chemical reactions involve the movement of electrons from one species to another. This movement either generates current, or it is driven by applied current.

The key reaction in electrochemistry is the…

 Lab: Chemistry

Tissue Regeneration with Somatic Stem Cells

JoVE 5339

Somatic or adult stem cells, like embryonic stem cells, are capable of self-renewal but demonstrate a restricted differentiation potential. Nonetheless, these cells are crucial to homeostatic processes and play an important role in tissue repair. By studying and manipulating this cell population, scientist may be able to develop new regenerative therapies for injuries and diseases.

 Developmental Biology
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