Essential Idea:
Information transferred from DNA to mRNA
is translated into an amino acid sequence
Understandings:
- Initiation of translation involves assembly of the components that carry out the process
- Synthesis of the polypeptide involves a repeated cycle of events
- Disassembly of the components follows termination of translation
- Free ribosomes synthesise proteins for use primarily within the cell
- Bound ribosomes synthesise proteins primarily for secretion or for use in lysosomes
- Translation can occur immediately after transcription in prokaryotes due to the absence of a nuclear membrane
- The sequence and number of amino acids in a polypeptide is the primary structure
- The secondary structure is the formation of alpha helices and beta pleated sheets stabilised by hydrogen bonding
- The tertiary structure is the further folding of the polypeptide stabilised by interactions between R groups
- The quaternary structure exists in proteins with more than one polypeptide chain
Applications:
- tRNA-activating enzymes illustrate enzyme-substrate specificity and the role of phosphorylation
Skills:
- Identification of polysomes in electron micrographs of prokaryotes and eukaryotes
- The use of molecular visualisation software to analyse the structure of eukaryotic ribosomes and a tRNA molecule