- Revision summary list for topic 7.2 Transcription
- Mindmaps
- Exam style question about gene expression
- Model answer
- Model answer
- Model answer
- 7.2 Transcription HL 1/1
Learn and test your biological vocabulary using these 7.2 Transcription flashcards.
Revision summary list for topic 7.2 Transcription
- The direction of Transcription is in a 5’ to 3’ direction as RNA polymerase adds the 5´ end (phosphate) of the free RNA nucleotide to the 3´ end of the growing mRNA molecule.
- Transcription is partly regulated by Nucleosomes in eukaryotes.
- Eukaryotes modify mRNA after transcription.
- Splicing of mRNA increases the number of different proteins an organism can produce.
- Gene expression is regulated by proteins that bind to specific base sequences in DNA. E.g. methylation.
- Gene expression is affected by the environment of a cell and of an organism.
Skills
- Awareness that the promoter region is an example of non-coding DNA.
- The skill to analyse changes in the DNA methylation patterns in connection with gene expression.
Mindmaps
These diagram summaries cover the main details of topic 3.5 Genetic modification.
Study them and draw your own list or concept map, from memory if you can.
Exam style question about gene expression
Explaining the control of gene expression, methylation and promoter regions is an important skill from this topic.
Answer the question below on a piece of paper, then check your answer against the model answer below.
Explain how nucleosomes, promoters and methylation can control of gene expression in eukaryotes. [4]
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This quiz contains multiple choice questions covering the understandings and skills in this topic.
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RNA polymerase adds an RNA nucleotide to a growing mRNA molecule during transcription.
In which direction does this happen?
The direction of Transcription is in a 5’ to 3’ direction as RNA polymerase adds the 5´ end (phosphate) of the free RNA nucleotide to the 3´ end of the growing mRNA molecule.
In eukaryotes DNA is often found associated with proteins, as shown in the diagram.
What is ithe name and function of these structures?
Transcription is partly regulated by the presence of nucleosomes in eukaryotes.
Their structure has two turns of DNA around each core of 8 histone proteins.
In eukaryote cells molecules of mRNA leave the nucleus and attach to ribosomes.
Which of the following can happen to them during this time?
Eukaryotes modify mRNA after transcription, introns are removed and the exons can be spliced in a variety of ways.
How could this be possible?
Splicing of mRNA increases the number of different proteins an organism can produce. Several different mRNA molecules can exist after RNA processing because exons are spliced in different ways.
In some parts of DNA there are proteins bound to the molecule. In some cases this also methylation. What is thought to be the function of these extra molecules?
Gene expression is regulated by proteins that bind to specific base sequences in DNA. - (eg. methylation)
A study of a gene responsible for the formation of red anthocyanin pigment in Maize plants found that plants homozygous in the gene for pigmentation developed bright red color when exposed to sun light and when the light was covered the bright red phenotype was not observed.
Which of the following points best explain this situation?
Gene expression can be affected by the environment of a cell and of an organism. In this case the light intensity affects expression of the anthocyanin gene causing the ed colour.
Which explanation best describes why the promoter region is 'non-coding DNA'?
Awareness that the promoter region is an example of non-coding DNA. It is not transcribed into mRNA used to build a protein, but it is involved in the control of gene expression.
In research geneticists were able to compare methylation in genes thought to be linked with drought tolerance in rice. This graphs shows the methylation levels found.
What can be concluded from this data about the correlation between methylation patterns and drought tolerance?
The skill to analyse changes in the DNA methylation patterns in connection with gene expression.
The diagram shows the general principal that more methylation is found in the drought tolerant rice.
There is no evidence that this is the cause, nor which genes are specifically involved.
Drag and drop activities
Test your ability to construct biological explanations using the drag and drop questions below.
Modification of pre-mRNA is an important process in producing mature mRNA for translation.
Drag and drop the correct words or phrase into the gap to outline mRNA modification.
nuclear pore sequence modified alternative transcription anti-sense increasing transcribed spliced introns sense exons pre-mRNA mature replication cosplicing
mRNA is from the DNA strand.
The mRNA formed directly from the DNA base is known as and is not ready for translation and needs to be .
This pre-mRNA contains introns and . The are removed and the exons together to produce mRNA ready for translation.
The introns can be spliced in different sequences, known as splicing. These alternatives will translate into polypeptides with amino acid chains in different positions, the variety of polypeptides that the cell can produce.
The mature mRNA leaves the nucleus via the to travel to a ribosome for .
mRNA transcribed from the DNA base sequence of a gene is modified before transcription.
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