BIO282 Lecture Notes - Lecture 10: Gene Expression, Consensus Sequence, Conserved Sequence
• Genetic material is the exact same in all cells
How do different cells of an organism containing same DNA sequences perform different functions ?
Gene Expression
Gene Expression
Gene expression is the flow of genetic information from DNA via RNA (transcription) to protein
(translation).
- In an organism all cells contain the same genetic information.
• Various cells can do diverse functions by expressing different genes.
Transcription
On this topic you will learn-
• Broader meaning/importance of gene expression
• RNA polymerases in prokaryotes and eukaryotes
• Transcription process
• Initiation and termination of transcription
• Promoters in prokaryotic and eukaryotic genes
• Sigma factors and their role in transcription
• Differences in three eukaryotic RNA polymerases and their promoters
Gene: part of DNA that gets transcribed into an RNA
5`UTR- 5`Untranslated region
3`UTR- 3`Untranslated region
If it doesn’t code a protein will it still be a gene? Yes there are some so the definition above it the
best.
Protein coding sequence (ORF) - part of mRNA that gets translated into a protein
Promoter- a part of DNA recognized by RNA polymerase for transcription
The gene goes from left to right. One is the coding and other one is the template strand. At eh time
of transcription the coding strand has not role. The template strand is the one that is recognised by
the RNA. The green bit is the part that is transcribed. The open reading frame is the part that makes
the protein. The translated region at the 5” end is not read. The end of the gene is noted through the
terminator sequences. Anything to the (right) is the upstream region and after the gene (left in the
picture below) is the downstream region.
There is a promoter just before the gene. This region is recognised by the RNA. There is so much
DNA so the promoter makes it recognisable for the binding and transcription.
These terms must be clear to you.
What are coding and template strands?
It is not always fixed that the top strand is coding and the bottom strand is the template. RNA
(Green) is being produced and it has the same as the coding strand. But RNA can’t have T.
Coding strand does not play a role in transcription.
Coding and Template strand are almost the same (T->U)
Template strand is not used for coding
Cells produce two types of RNAs
• Informational RNAs- contain message of amino acid sequence of proteins. (get translated into
proteins)
• Functional RNAs- rRNAs, tRNAs, snRNAs, scRNAs (not translated into proteins)
The enzyme that synthesizes RNAs is called RNA polymerase
Functional do not get changed, they function directly without translation.
Document Summary
Genetic material is the exact same in all cells. Gene expression is the flow of genetic information from dna via rna (transcription) to protein (translation). In an organism all cells contain the same genetic information: various cells can do diverse functions by expressing different genes. On this topic you will learn: broader meaning/importance of gene expression, rna polymerases in prokaryotes and eukaryotes, transcription process. Initiation and termination of transcription: promoters in prokaryotic and eukaryotic genes. Sigma factors and their role in transcription: differences in three eukaryotic rna polymerases and their promoters. Gene: part of dna that gets transcribed into an rna. Yes there are some so the definition above it the best. Protein coding sequence (orf) - part of mrna that gets translated into a protein. Promoter- a part of dna recognized by rna polymerase for transcription. One is the coding and other one is the template strand. At eh time of transcription the coding strand has not role.
