Essential idea: Information stored as a code in DNA is copied onto mRNA.
"The genetic code is frequently referred to as a blueprint because it contains the instructions a cell requires in order to sustain itself. We now know that there is more to these instructions than simply the sequence of letters in the nucleotide code, however. For example, vast amounts of evidence demonstrate that this code is the basis for the production of various molecules, including RNA and protein ... In transcription, a portion of the double-stranded DNA template gives rise to a single-stranded RNA molecule."
The image above shows how DNA is used as a template to create portable molecules of genetic code, i.e. mRNA, that can leave the nucleus for translation in other regions of the cell.
Understandings, applications and skills
|7.2.U1||Transcription occurs in a 5’ to 3’ direction. [RNA polymerase adds the 5´ end of the free RNA nucleotide to the 3´ end of the growing mRNA molecule.]|
|7.2.U2||Nucleosomes help to regulate transcription in eukaryotes.|
|7.2.U3||Eukaryotic cells modify mRNA after transcription.|
|7.2.U4||Splicing of mRNA increases the number of different proteins an organism can produce.|
|7.2.U5||Gene expression is regulated by proteins that bind to specific base sequences in DNA.|
|7.2.U6||The environment of a cell and of an organism has an impact on gene expression.|
|7.2.A1||The promoter as an example of non-coding DNA with a function.|
|7.2.S1||Analysis of changes in the DNA methylation patterns.|
[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.
Transcription by St. Olaf College
mRNA Splicing by Sumanas Inc (contains more detail than you need)
3D Animation of RNA Splicing by the DNA Learning Center
RNA Splicing by McGraw and Hill (contains more detail than you need)
Alternative Splicing explained in this tutorial by Nobelprize.org
Nature of Science
Looking for patterns, trends and discrepancies—there is mounting evidence that the environment can trigger heritable changes in epigenetic factors. (3.1)
DNA and Genetics is fast evolving area of Biological research. One of the very interesting areas of current research is Epigenetics. How does this fit in with what you know about DNA and how is it contrary to accepted theory?
Learn more about Epigenetics by Learn.Genetics
Theory of knowledge
The nature versus nurture debate concerning the relative importance of an individual’s innate qualities versus those acquired through experiences is still under discussion. Is it important for science to attempt to answer this question?