7.2 factors effecting gene expession Flashcards
(15 cards)
The name of a sequence of triplets on a section of DNA used to from a strand of pre-RNA
Cistron
Describe how free nucleotides are bonded together in the correct sequence in pre-mRNA
RNA polymerase
Hydrogen bonds from between complementary bases
Sequence of bases determines sequence of pre-mRNA
Phosphodiester bonds
Condensation reaction
Explain the function of the codons at each of a strand of mRNA, during the process of translation
Start needed to begin protein synthesis
Stop needed to end protein synthesis
Suggest why a variety of different protein structures could’ve be formed from the polypeptides synthesised using the mRNA molecules from a single gene
Genes activated an inactivated by transcription factors, altering the sequence of amino acids produced
Changes in bond e.g. H bonds
Different 3D shape
Change in secondary or tertiary shape due to variation in mRNA
Suggest how IAA can cause cells to produce proteins by interacting with transcriptions factors
IAA binds to transcription factors
Causing a secondary messenger
Activity in promoter region
Forming mRNA
Genes transcribed and proteins formed
Explain how the formation of mRNA enables 25 000 genes to produce 100 000 proteins
It was assume 1 gene makes 1 protein
1 gene can make more than one mRNA
Removal of Exons by spicing produces different proteins
Post transcriptional change
How epigenetic changes can affect the functioning of the genome
Methyl groups attach to gene at CpG sites preventing transcription factor binding and repressing gene expression.
Acetyl group attach to a histone reducing condensation allowing transcription factor binding and gene expression
Histones are modified effecting binding of other proteins to DNA
Because DNA Is wrapped around histones
Why is gene expression regulated
To allow variation in proteins created
To avoid unwanted proteins at the wrong time
To allow permanent differentiation
What effects gene expression
Transcription factors (nucleus)
Post transcriptional change (cytoplasm)
Epigenetic chromatin accessibility
What is a transcription factor
A protein which regulates transcription of a gene
How transcription factors work part 1
Change the ability of RNA polymerase to bind to correct locus on DNA
Interfere with promoter region of DNA where RNA polymerase must bind
Factors can stop or help polymerase binding
Each factor contains a complementary site for the promoter
Promoter region
Non coding region of DNA immediately before the gene
Enhancer region
Sometimes multiple promoter are used to cause gene expression
Change structure of chromatin when activated
Multiple transcription factors can be used
Post transcriptional change
mRNA is modification after transcription to pre-mRNA to cause greater variation in the gene.
Pre MRNA includes intros (Non coding areas) and exons
Process of post transcriptional change
Pre-MRNA is capped to avoid attack from enzymes
Introns are removed from the mRNA
RNA splicing occurs: the exons join together to form a single long mRNA molecule
By spliceosome enzymes
In some cases exons are moved as well to give different proteins
