Macromolecules Of The Cell

The six basic molecules are used by all cells to construct five essential macromolecules. These include proteins, RNA, DNA, phospholipids, and sugar polymers, known as polysaccharides. Amino acids are linked together by peptide bonds to construct a protein. A peptide bond is formed by linking the carboxyl end of one amino acid to the amino end of second amino acid. Thus, once constructed, every protein has an amino end and a carboxyl end. An average protein may consist of Macromolecules of the...

The Problem of Immune Rejection

Stem cell therapies all require that the cells, usually isolated from human embryos, be injected into a patient, where they will effect whatever repairs are necessary. This is equivalent to a tissue or an organ transplant, and like any conventional transplant, the stem cells will have to deal with the patient's immune system. Transplants are categorized according to the source of the transplant tissue. Autografts are transplants of tissue from one part of an individual to some other area of the...

Immune Deficiencies

Cell Second Form

All animals have an immune system that is designed to combat invading microbes, and without it we face certain death from a multitude of diseases. The immune system consists of an enormous population of white blood cells that appear in many different forms, the most important of which are the B cells, T cells, and macrophages. B and T cells are lymphocytes that develop in bone marrow and the thymus, respectively. Macrophages are phagocytic blood cells that confront invaders head-on by eating...

Cardiovascular Disease

A potentially deadly form of cardiovascular disease affecting the coronary arteries is currently being treated with stem cells in animal models. Coronary arteries carry blood to the cardiomyocytes, or heart muscle cells, and if they become blocked or otherwise damaged, the cardiomyocytes die from lack of oxygen. In serious cases, this can lead to a massive heart attack and death of the patient. In milder cases, damage to the heart is minimal, but coronary circulation is insufficient to allow...

Growing Organs from Cultured Stem Cells

Stem Cell Research Growing Organs

In the summer of 2002, researchers at the biotech company Advanced Cell Technology published a paper in the journal Nature Biotechnology in which they described their attempts to grow kidneys from cloned cow embryos. This article, entitled Generation of Histocompatible Tissues Using Nuclear Transplantation, was also intended to demonstrate the effectiveness of therapeutic cloning, whereby an animal is cloned and the subsequent embryos are used as a source of histocompatible (immune-system...

Collecting Human Embryonic Stem Cells

Chromosome Idiograms 500 Bph

Human embryonic stem cells were collected for the first time in 1998 by two different research teams, one headed by Dr. James Thomson at the University of Wisconsin, and the other by Dr. John Gearhart at Johns Hopkins University. Thomson's group obtained cells from five-day-old blastocysts that were obtained from in vitro fertilization (IVF) clinics Gearhart's team isolated cells from two- to four-month-old fetuses that were obtained after elective abortions. The cells obtained from the...

Future Prospects for Adult Stem Cells

Adult stem cells can differentiate into several different cell types, but the plasticity of these cells is in question. However, many people, scientists included, are uncomfortable with the current practice of obtaining stem cells from human blastocysts or fetuses and hope that adult stem cells will eventually resolve the issue. Even if the social objections to the use of human ES cells did not exist, the study of adult stem cells would still be essential because the human ES cells now being...