What is the composition of protoplasm

• Exosomes are saucer-shaped vesicles of 30–100 nm in diameter, which are delimited by a lipid bi-layer and which float at a density of 1.13–1.19 g ml −1 in sucrose gradients. These vesicles are secreted by various cells in culture. • Analysis of the protein composition of exosomes that are secreted by various cells reveals the presence of some common proteins, which define exosomes as a bona fide secreted subcellular compartment, as well as the presence of some cell-type-specific proteins, which could mediate the different functions of exosomes that are produced by different cell types. • All of the proteins that have been identified in exosomes are localized in the cell cytosol or endosomal compartments, never in the endoplasmic reticulum, Golgi apparatus, mitochondria or nucleus. Exosomes also contain some plasma-membrane proteins, which have been described also in endosomal compartments. These observations are consistent with the proposed origin of exosomes as internal vesicles of late multivesicular compartments. • Formation of the internal vesicles of multivesicular bodies by inward budding from the limiting membrane involves a budding event of inverse membrane orientation compared with the classical intracellular budding events that take place in a cell. All inverse budding events seem to be correlated with an inversion of the transmembrane partition of the lipid phosphatidylserine. • Membrane exchanges between cells have been described during the interactions of T ...

Protoplasm refers to the living substance which makes up a cell. Biologists tend to speak about the cell nucleus and the cytoplasm It is surrounded in plant cells by a cell wall. The entire cell of animal cells is made of protoplasm, surrounded by a cell membrane. In living organisms, the protoplasm consists of around 75–80 percent water Hugo von Mohl first used the word "protoplasm" in 1846 to describe the substance in plant cells besides the cell wall, the cell nucleus and the vacuole Protoplasm Definition In general, the word protoplasm is used to refer to the living parts of a cell. However, the term protoplasm is not widely used these days, since it was originally used to indicate that a cell comprises only two elements, a nucleus and a plain, homogeneous cytoplasm. We now realize the cytoplasm is very complex, and it contains complicated organelles. Nevertheless, we now refer to the protoplasm outside of the nucleus as the cytoplasm in eukaryotes, such as plants and animals, and the protoplasm inside the nucleus as nucleoplasm. In prokaryotes the content of a cell is called the cytoplasm collectively. Structure of Protoplasm and its Components Structural, it comprises 3 parts, like 1) Plasma/cell membrane 2) Cytoplasm 3) Nucleus Component of Protoplasm The major component of a protoplasm is the cytoplasm that exists in eukaryotes between the cell membrane and the nucleus. The cytoplasm is responsible for maintaining an environment which will allow the various organel...

ADVERTISEMENTS: In this article we will discuss about Protoplasm:- 1. Meaning of Protoplasm 2. Nature of Protoplasm 3. Properties. Meaning of Protoplasm: The term protoplasm (Gr., protos = first + plasma = anything formed) was first coined in 1840 by who used the word to designate the living substance in the embryo of animals. Earlier the protoplasm was first of all observed by (1772) and the French zoologist (1935) first of all recognised its significance and called it “sarcode”. Later, Hugo Von Mohl applied this term to embryonic cells of plants. In 1861, Schultze established the similarity which exists in the protoplasm of animal and plant cells, thus, offering a theory which was later called the “protoplasm theory” which states that the cell is an accumulation of living substances having a nucleus and limiting cell membrane. Gradually, protoplasm came to mean all living matter out of which plants and animals are formed. ADVERTISEMENTS: Huxley (1868) referred to protoplasm as the “physical basis of life”. It was first thought that protoplasm was a definite chemical substance, but investigations have shown that it is not a single chemical substance but is made up of different compounds and that it differs in every species of plant and animal life and probably in every different kind of cell. For quite a long time, the protoplasm and cytoplasm were regarded to be synonyms. However, after recent investigations the protoplasm is a term used for the transparent, homogeneous ...