(51)
1. Forklare ribosomets funktion. Kort beskrive dets struktur som store rRNA-protein komplekser opbygget af to subunits i alle organismer
Devlin, s.242-245
Stryer, s. 823

Function - Ribosomes are workbenches for protein synthesis. They coordinate the interplay of charged tRNAs, mRNA and proteins, which leads to protein synthesis.

Structure - Ribosomes are complex ribonucleoprotein particles made up of 2 dissimilar subunits - a big and a small one. Each subunit includes an RNA core, folded into a specific 3-dimensional structure, upon which proteins are positioned through protein-RNA and protein-protein interactions. The RNA makes up a total of 2/3 of the ribosome, while the protein part 1/3. The key sites in a ribosomes are composed almost entirely of RNA.

Polysome - several ribosomes can translate a single mRNA molecule simultaneously.

Ribosomes occur either free in cytosol or are bound to rER membranes.

The free ribosomes synthesize proteins that remain within the cytosol or become targeted to the nucleus, mitochondria or some other organelle.

Membrane-bound ribosomes synthesizes proteins that will be secreted from the cell or make up and function in other cellular membranes and vesicles.

tilbage til molekylær biologi