Does the synthesis of intracellular proteins need to go through the endoplasmic reticulum

The synthesis of intracellular proteins does not need to go through the endoplasmic reticulum. Synthesis is on free ribosomes, and endoplasmic reticulum is processing. However, intracellular proteins do not necessarily need to be processed, and intracellular proteins such as cytoplasmic matrix proteins, mitochondria, chloroplast partial proteins, and nuclear proteins do not need to be processed by the endoplasmic reticulum and Golgi apparatus.

Membrane proteins, secreted proteins, lysosomal proteins and other proteins need to be processed into mature proteins by the endoplasmic reticulum, and then further processed into mature proteins by the Golgi apparatus, and then sorted, concentrated, packaged, secreted to the extracellular or transported to various membrane structures in the cell.

The difference between secretory and intracellular protein synthesis processes.

1. First of all, the transcription of DNA in the nucleus forms messenger RNA, messenger RNA passes through the nuclear pore of the nucleus and combines with ribosomes, ribosomes use amino acids in the cytoplasm to use messenger RNA as a template to synthesize proteins, and the synthesized proteins are further processed and folded in the rough endoplasmic network attached to ribosomes, and transported to the Golgi apparatus in the form of vesicles, 2. The Golgi apparatus is further processed by it, and finally fused with the cell membrane in the form of vesicles, and the secreted proteins in the vesicles are secreted to the outside of the cell.

Proteins are synthesized on free ribosomes (amino acid dehydration condensation), and endoplasmic reticulum, Golgi apparatus, etc., are processing sites.

For example, cytoplasmic matrix proteins, mitochondria, chloroplast partial proteins, nuclear proteins and other intracellular proteins. They do not need to be processed by endoplasmic reticulum and Golgi apparatus. And proteins such as membrane proteins, secreted proteins, lysosomal proteins, etc.

They need to be processed by the endoplasmic reticulum into more mature proteins, and then further processed by the Golgi apparatus to become mature proteins, and most of them need the process of endocytosis and exocytosis.

Therefore, intracellular proteins do not need to go through organelles such as endoplasmic reticulum.

Biological knowledge should not be memorized by rote, and it will be easier to understand and remember by trying to think about analysis from a functional point of view.

Yes, intracellular proteins do not require endoplasmic reticulum and Golgi processing.

Intracellular proteins are synthesized from free ribosomes in the cytoplasm and do not undergo endoplasmic reticulum, Golgi apparatus processing, and exocytosis of the cell membrane.

Intracellular proteins do not need to be transported outside the cell membrane and only function inside the cell, such as respiratory enzyme DNA polymerase, various aminotransferases, DNA helicase, RNA polymerase and other enzymes necessary for cellular life activities.

There are free ribosomes and ribosomes attached to the endoplasmic reticulum in the cell. Free ribosomes are the ones that make intracellular proteins, which do not pass through the endoplasmic reticulum and the Golgi apparatus. Ribosomes attached to the endoplasmic reticulum, the ribosomes only convert amino acids into peptide chains, and further processing is handed over to the endoplasmic reticulum and the Golgi apparatus, and finally secreted outside the cell by the cell membrane.

In fact, there are many types of intracellular proteins, and different proteins may be formed in different ways.

No. Proteins are all synthesized on ribosomes and start in the cytoplasmic matrix, but some proteins are synthesized in the endoplasmic reticulum soon after the synthesis begins, these proteins are:1

extracellular secreted proteins, such as antibodies, hormones; 2.transmembrane proteins, and determines the arrangement of membrane proteins in the membrane; 3.Enzymes that need to be tightly separated from other cellular combinations, such as various hydrolytic enzymes of lysosomes; 4.

Proteins that need to be modified, such as glycoproteins.

Ribosomes, formerly known as "ribonucleosomes" or "nucleosomes", are generally considered to be a type of organelle in cells.

Ribosomes are present in cells except mammalian mature red blood cells, plant sieve tube cells. In general, prokaryotic cells have only one ribosome, whereas eukaryotic cells have two types of ribosomes (where the ribosomes in the mitochondria are not the same as the cytoplasmic ribosomes).

It should be pointed out that ribosomes are sometimes not considered to be a class of organelles, but intracellular macromolecules, because of their structural differences from those of other organelles, such as the absence of membrane coating, the composition of two subunits, and the ability to attach to the endoplasmic reticulum or be free of the cytoplasm due to functional requirements.

Ribosomes are responsible for the central law of the process of moving from RNA to protein in the cell, a process known in biology as translation. Before translation, the small subunit of ribosomal will first bind to messenger RNA (mRNA) transcribed from the nucleus, and then combine with the large subunit of ribosomal to form a complete ribosome, and then use the amino acid molecules transported by transfer RNA (tRNA) in the cytoplasmic matrix to synthesize polypeptides. When the ribosome completes the translation of a single strand of mRNA, the large and small subunits are separated again.

There are two types of endoplasmic reticulum, rough endoplasmic reticulum and smooth endoplasmic reticulum.

A large number of ribosomes are attached to the rough endoplasmic reticulum, which is capable of synthesizing membrane proteins and secreted proteins.

The rough endoplasmic reticulum is not only a scaffold for ribosomes, but also a transport channel for secreted proteins synthesized on ribosomes. In addition, it can be used to modify the polypeptide chain synthesized by ribosomes, or for its own assembly and generation.

The function of the rough endoplasmic reticulum is to synthesize protein macromolecules and transport them from the cell or to other parts of the cell.

Endoplasmic reticulum. Processing of proteins:

Including glycosylation, hydroxylation, acylation, disulfide bonding.

formation, etc., the main of which is glycosylation, where almost all proteins synthesized in the endoplasmic reticulum are eventually glycosylated. The effects of glycosylation are: to make proteins resistant to the action of digestive enzymes; Gives proteins the function of conducting signaling; Some proteins fold properly only after glycosylation.

Glycans are generally linked to 4 amino acids.

, divided into 2 types:

O-linked glycosylation: OH linkage with Ser, THR, and HYP, and the linked sugar is galactose or N-acetylgalactosamine, in the Golgi apparatus.

O-linked glycosylation. N-linked glycosylation: Nh2 linked to asparagine residues, and the sugar is N-acetylglucosamine.

The endoplasmic reticulum is an N-linked glycosylation. The donor of sugar is nucleotide sugar, such as CMP-sialic acid.

GDP-mannose, UDP-N-acetylglucosamine, etc. Sugar molecules are first transferred by glycosyltransferases to dolichol phosphate molecules on the membrane to assemble oligosaccharides.

Chain. It is then transferred by oligosaccharyltransferases to asparagine residues of a specific sequence of the newly synthesized peptide chain (ASN-X-Ser or ASN-X-THR).

The synthesis of secreted proteins requires the processing of endoplasmic reticulum and Golgi apparatus, and some intracellular proteins, such as lysosome hydrolase, require the processing of endoplasmic reticulum and Golgi apparatus

So the answer is: false.