Tsütoplasmat

Tsütoplasmat, commonly referred to as cytoplasm in English, is the contents of a cell enclosed by the plasma membrane, excluding the nucleus. In eukaryotic cells it comprises the cytosol—the gel-like aqueous phase rich in water, ions, metabolites, and soluble enzymes—and the organelles suspended within it, such as mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and peroxisomes. In plant cells chloroplasts and large central vacuoles are also part of the cytoplasmic space. In prokaryotes the cytoplasm includes the cytosol, ribosomes, and the nucleoid region where the chromosome resides.

The cytoplasm houses most cellular metabolism. It is the site of glycolysis, amino acid synthesis, and other reactions, and it contains free ribosomes for protein synthesis. It also serves as a medium for diffusion and as a scaffold for the cytoskeleton, which includes actin filaments, intermediate filaments, and microtubules. The cytoskeleton organizes cell shape, enables movement, and helps position organelles and vesicles.

The cytoplasm is a crowded, highly organized milieu. Macromolecular crowding affects reaction rates and diffusion. Organelles perform specialized tasks, but many processes remain interconnected through signaling pathways that traverse the cytosol.

Differences between cell types reflect morphology and function. In plant cells, chloroplasts contribute to energy metabolism, and the vacuole modulates turgor pressure. In animal cells mitochondria and lysosomes are common sites of energy production and macromolecule degradation. In bacteria and other prokaryotes, the cytoplasm contains ribosomes and the nucleoid but lacks membrane-bound organelles.

Etymology: from Greek cyto- cell and plasma something formed.