Cellular component

Abstract: The invention relates to host cells and methods of preparing a substantially RNA-free cellular component, comprising culturing cells producing the cellular component in a medium and lysing the cells to produce a cell lysate, wherein the cell lysate contains the cellular component and sufficient RNase activity to degrade substantially all of the RNA molecules present in the cell lysate. The invention also relates to substantially RNA-free cellular components.

Abstract: This chapter introduces the most important molecular and cell biological principles needed to understand stem cells. Humans and animals, as well as plants and trees, contain many different functional organs and tissues. They are composed of a large variety of cells. Cells are therefore the basic building blocks, which make up the organism. All animal cells have a similar structure: an outer layer called the plasma membrane, made up of a double layer of lipid molecules, and an inner fluid known as cytoplasm. Most cell organelles are themselves separated from the cytoplasm by their own membranes. The form of the cell is determined and supported by the cytoskeleton, a flexible scaffolding composed of polymers of protein molecules which form a network that shapes the cell and allows it to move and walk. Inside the cell countless proteins—sometimes in cooperation with RNA molecules—facilitate the chemical and physical reactions and transport of other molecules required to carry out specific cellular functions. Although cells can have different shapes and functions, the DNA sequence in all cells of a given individual is in principle identical (with the exception of certain blood cells). Other prominent structures in the cell are the mitochondria. These organelles are present in large numbers and generate the energy required by the cell.

Abstract: The invention relates to a method of purifying a cellular component substantially free of chromosomal DNA. The method comprises culturing cells producing the cellular component in a medium. The chromosomal DNA of the cells is then exposed to a restriction enzyme such that it is cleaved. The cellular component to be purified is resistant to such cleavage.

Abstract: Cells are the individual units of life. They are made up of protoplasm surrounded by a membrane that separates them from their environment. Cells contain structures or organelles that carry out functions vital for the cell's survival. Each structure or organelle is also surrounded by, or composed of, membrane which allows compartmentalization of the various cell functions. Protoplasm within the cell is known as cytoplasm. Cells also contain genetic material that directs activity, and machinery for obtaining energy. Energy in the form of nutrient macromolecules is taken into vacuoles by the process of endocytosis and digested by enzymes contained in lysosomes. Energy is released in discrete packages of ATP via aerobic respiration in the mitochondria. Cell theory states that all organisms are made up of cells and their products; new cells arise only from existing cells; all cells have the same fundamental make-up and chemical processes; the activity of the organism results from the interdependence and cooperative work of groups of cells. The eukaryotic cell is divided into two regions: the nucleus, a spherical or oval structure usually situated near the centre containing the genetic material, and the cytoplasm in which lie the other organelles and the fluid surrounding them (the cytosol). Metabolic processes within the cell synthesize (and degrade) proteins for use by the cell or for export. These processes are catalysed by enzymes, which are proteins. Cells differ in their structure depending on their function and no cell can be described as typical. However, there are features common to most cells and the various organelles are found in most body cells (Figure 1).