Explain how a gene directs thesynthesis of a protein. Include in your explanatio

Question

Explain how a gene directs thesynthesis of a protein.

Include in your explanation thewords amino acid, anti-codon, codon, cytoplasm, DNA,

mRNA, nucleotide, nucleus,ribosome, RNA polymerase, tRNA, transcription, and

translation.

This is what I could come up with so far:

A gene is made up of DNA, which resides in the nucleus of a cell.RNA polymerase will 'read' a gene by matching each nucleotide (thebuilding blocks of DNA: A, C, T or G) in a gene according to thebase pairing rule with a complementary RNA nucleotide: A is matchedwith U, T with A, C with G and G with C. This will form a strand ofmessenger RNA which is transported to thecytoplasm.

Explanation / Answer

Protein synthesis is the creation of proteinsusing DNA andRNA. Proteinscan often be synthesized directly from genes by translatingmRNA. When aprotein is harmful and needs to be available on short notice or inlarge quantities, a proteinprecursor is produced. A proproteinis an inactive protein containing one or more inhibitorypeptides that can be activated when the inhibitorysequence is removed by proteolysisduring post-translational modification. A preproteinis a form that contains a signal sequence (an N-terminal signalpeptide) that specifies its insertion into or throughmembranes; i.e., targets them for secretion. The signal peptide iscleaved off in the endoplasmicreticulum. Preproproteinshave both sequences (inhibitory and signal) still present.

For synthesis of protein, a succession of tRNA molecules chargedwith appropriate amino acids have to be brought together with anmRNA molecule and matched up by base-pairing through theiranti-codons with each of its successive codons. The amino acidsthen have to be linked together to extend the growing proteinchain, and the tRNAs, relieved of their burdens, have to bereleased. This whole complex of processes is carried out by a giantmultimolecular machine, the ribosome, formed of two main chains ofRNA, called ribosomal RNA (rRNA), and more than 50 differentproteins. This molecular juggernaut latches onto the end of an mRNAmolecule and then trundles along it, capturing loaded tRNAmolecules and stitching together the amino acids they carry to forma new protein chain.

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