Ekspresi genTranslasi

Ekspresi Gen Transkripsi Translasi

TranslasiTranslasi adalah proses sintesis protein dari template mRNA Proses ini melibatkan beberapa molekul kunci, antara lain mRNA, tRNA, ribosom (unit kecil & unit besar), peptidil/protein polimerase, dan faktor pelepas (release factor). Proses translasi terbagi dalam 3 tahap, yaitu: initiasi, elongasi, dan terminasi.

The codons found within the mRNA.mRNA contains codons that will encode for specific amino acids.Eukaryotic mRNA, the substrate for translation, has a unique 3'-end called the poly-A tail.

Kodon Triplet

tRNA is another keymolecule. It contains an anticodon that is complementary to the mRNA codon to which it binds. The first codon is typically AUG. Attached to the end of tRNA is the corresponding amino acid. Methionine corresponds to the AUG codon.

t-RNA

t-RNA

t-RNA

Ribosom

Proses translasi terbagi dalam 3 tahap, yaitu: Initiasi elongasi terminasi.

The small subunit of the ribosome attached to the mRNA. A methylated cap is found at the 5'-end. Translation initiation begins when the small subunit of the ribosome attaches to the cap and moves to the translation initiation site.

Elongasi

ElongasiThe large subunit now binds to create the peptidyl (or P) site and the aminoacyl (or A) site. The first tRNA occupies the Psite. The second tRNA enters the A-site and is complementary to the second codon.The methionine is transferred to the A-site amino acid, the first tRNA exits, the ribosome moves along the mRNA, and the next tRNA enters. These are the basic steps of elongation.As elongation continues, the growing peptide is continually transferred to the A-site tRNA, the ribosome moves along the mRNA, and new tRNAs enter.All mRNAs are read in the 5 to 3 direction

TerminasiApabila pada A-site terbaca kodon stop (UAA/UAG/UGA), maka protein release factor akan menduduki A-site dan translasi segera berakhir (terminated) Kompleks ribosom terurai, dan protein yang dihasilkan akan terlepas.

PolisomClusters of ribosomes may sit on a mRNA and make proteins, each making a strand of polypeptides. These clusters are called polyribosomes. When they are free in the cytoplasm, they are called free polyribosomes (linked by the mRNA). Or, they may bind to rough endoplasmic reticulum.

Ekspresi Gen Pada Sel EukariotikPada sel eukariotik, transkripsi berlangsung di dalam nukleus, dan translasi di sitoplasmaTranslasi berlangsung setelah transkripsi selesai

Ekspresi Gen Pada Sel ProkariotikDalam sel prokariotik, transkripsi dan translasi berlangsung di sitoplasma simultan

ersinaga2003@yahoo.com.sg

**biosintesis protein-transkripsi- ernawati sinaga**********************biosintesis protein-transkripsi- ernawati sinaga*biosintesis protein-transkripsi- ernawati sinaga**