Protein synthesis requires the use of mrna, which protein synthesis requires the use of mrna, which carries the message to the nucleus to synthesize new dna during cell division. is translated by the ribosomes into the amino acid sequences of proteins. is made in the nucleolus. must be made by the ribosomes.

is translated by the ribosomes into the amino acid sequences of proteins.

Explanation:

Protein synthesis is also called gene expression and it involves how the information in a DNA molecule to used to synthesize useful gene products called proteins. The process of synthesizing proteins in living cells occurs in two major stages namely: transcription and translation.

Transcription generally involves the synthesis of a mRNA molecule using a DNA template. The mRNA transcript is then used to direct the synthesis of Protein in the next stage (translation). Translation, which occurs in the ribosome, involves the use of the mRNA nucleotide sequence to produce an amino acid sequence, which will eventually become a protein.

1st step: the transcription of the genes of the DNA into pmRNA ( pre-messenger RNA) takes place in the nucleus.

For each gene, only one strand of the DNA is transcribed but this strand varies according to the genes.

RNA synthesis is catalyzed by RNA polymerase, an oligomeric enzyme. There are 3 types in eukaryotes.

Transcription occurs from the 5 'end to the 3' end of the genes.

2nd step: the processing of the pmRNA takes place in the nucleus

at. a cap of 7-methylguanosine triphosphate is added to the 5 'end of the pmRNA

b. a poly-A tail (50 to 250 nucleotides of adenine) is added to the 3 'end of the pmRNA

These modifications protect messenger RNA from too rapid degradation in the cytoplasm.

c. excision of introns (the parts of the gene that do not encode a polypeptide) of the pmRNA

d. splicing of the exons (the coding strands) of the pre-messenger RNA.

The pre-messenger RNA thus mature becomes messenger RNA (mRNA).

The mRNA is then exported to the cytoplasm via nuclear pores.

3rd step: the translation of the mRNA into protein takes place in the cytoplasm at the level of ribosomes and requires the presence of transfer RNA (tRNA) loaded with the corresponding amino acids and energy in the form of GTP.

tRNAs are synthesized in the nucleus.

The synthesis proceeds from the N-terminus of the protein to the C-terminus.

4th step (depending on the proteins): co-translational or post-translational modifications such as glycosylation (covalent binding of oses to proteins) which takes place in the endoplasmic reticulum and is then finished in the Golgi apparatus.

In prokaryotes, transcription, and translation take place in the cytoplasm and can be simultaneous.