Essential idea: Information transferred from DNA to mRNA is translated into an amino acid sequence.
"The genes in DNA encode protein molecules, which are the "workhorses" of the cell, carrying out all the functions necessary for life ... In the simplest sense, expressing a gene means manufacturing its corresponding protein" http://www.nature.com/scitable/topicpage/translation-dna-to-mrna-to-protein-393
The image above shows a table used to translate mRNA codons (which have been transcribed from DNA) into amino acids.
Understandings, applications and skills
| 7.3.U1 | Initiation of translation involves assembly of the components that carry out the process. [Examples of start codons are not required. Names of the tRNA binding sites are expected as well as their roles.] |
| 7.3.U2 | Synthesis of the polypeptide involves a repeated cycle of events. |
| 7.3.U3 | Disassembly of the components follows termination of translation. [Examples of stop codons are not required.] |
| 7.3.U4 | Free ribosomes synthesize proteins for use primarily within the cell. |
| 7.3.U5 | Bound ribosomes synthesize proteins primarily for secretion or for use in lysosomes. |
| 7.3.U6 | Translation can occur immediately after transcription in prokaryotes due to the absence of a nuclear membrane. |
| 7.3.U7 | The sequence and number of amino acids in the polypeptide is the primary structure. |
| 7.3.U8 | The secondary structure is the formation of alpha helices and beta pleated sheets stabilized by hydrogen bonding. |
| 7.3.U9 | The tertiary structure is the further folding of the polypeptide stabilized by interactions between R groups. [Polar and non-polar amino acids are relevant to the bonds formed between R groups.] |
| 7.3.U10 | The quaternary structure exists in proteins with more than one polypeptide chain. [Quaternary structure may involve the binding of a prosthetic group to form a conjugated protein.] |
| 7.3.A1 | tRNA-activating enzymes illustrate enzyme–substrate specificity and the role of phosphorylation. |
| 7.3.S1 | Identification of polysomes in electron micrographs of prokaryotes and eukaryotes. |
| 7.3.S2 | The use of molecular visualization software to analyse the structure of eukaryotic ribosomes and a tRNA molecule. |
[Text in square brackets indicates guidance notes]
Presentation and notes
The presentation is designed to help your understanding. The notes outline is intended to be used as a framework for the development of student notes to aid revision.
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Weblinks
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Translation
Video tutorial on translation by Stephanie Castle Translation by St. Olaf College How translation works by McGraw and Hill Visual of translation by HHMI Translation by Harvard Uni DNA Translation by John Kyrk Polysomes Polyribosomes by Sumanas Inc. |
Protein structure
Proteins and Protein Structure by Terry Brown Proteins (structure, bonding and function) by June Steinberg Levels of protein structure by Biotopics Amino acids and proteins by John Kyrk Protein Structures and Protein Folding by John Gianni Life Cycle of a Protein by Sumanas |
Nature of Science
Developments in scientific research follow improvements in computing—the use of computers has enabled scientists to make advances in bioinformatics applications such as locating genes within genomes and identifying conserved sequences. (3.7)
