Protein Synthesis: from the Nucleus to the Ribosomes

Protein Synthesis: from the Nucleus to the Ribosomes

The central dogma of molecular biology states that DNA will be converted into RNA by a process called transcription and RNA will be converted to protein by a process called translation. Translation in non-reversible whereas transcription could be reverted: there are viruses, such as HIV, that can make DNA from RNA with the enzyme called reverse transcriptase.

The nuclear envelope is built from a double-layered membrane. The inner and outer membranes of the nuclear envelope connect to form pores which are com-plicated structures controlling travel between the nucleus and the cytoplasm. Inside of the nuclear envelope there is the nucleoplasm.

Nuleoplasm contains chromatin (chromosomes). Chromosomes store genetic information in the form of DNA molecules. Each chromosome consists of a chain of nucleosomes, which are condensed long DNA molecules and their associated histone proteins. Chromatin is just another word for non-condensed chromo-somes. Visible parts of chromatin (globules, filaments) correspond with non-functional DNA.

Ribosomes, which are particles that contain RNA and proteins, synthesize pro-teins. The rough endoplasmic reticulum (RER) has ribosomes along its sur-face, and the proteins they create are either secreted or incorporated into mem-branes in the cell. The Golgi apparatus (AG) is made of membranous sacs which are flattened and stacked, it modifies, packages, and sorts proteins and carbohy-drates for the cell; this is not an essential component of cell.