7.2 Factors affecting gene expression Flashcards
What are transcription factors?
proteins that bind to DNA in the nucleus and affect the process of transcribing genetic material
How do transcription factors regulate gene expression?
Transcriptions factors (tf) bind to specific base sequence to control gene expression:
- promotor sequences: tf bind to stimulate transcription
- enhancer sequences: tf bind and regulate activity of DNA by changing chromatin structure - making it more/less available to RNA polymerase, stimulating/preventing transcription of the gene
What is RNA splicing?
When pre-mRNA is modified and joined to spliceosomes to produce mature mRNA
How does RNA splicing result in different products from a single gene?
What is epigenetics?
the study of genetic control by factors other than base sequences
What are the types of epigenetic modification?
DNA methylation
DNA demethylation
histone modification
RNA splicing
How do epigenetic modifications allow cell differentiation to occur?
with epigenetics - a cell becomes specialised for a particular function and produces only its own specific proteins/ ‘housekeeping’ proteins.
What is DNA methylation and its effect?
adding a methyl group to a CpG site (cytosine next to guanine)
prevents transcription
affects histone structure to make more/less DNA accessible to RNA polymerase
What is DNA demethylation and its effect?
removal of a methy group from a methylated DNA
enables genes to be active so they can be transcribed
What is histone acetylation and its effect?
addition of acetyl group (-COCH3) to lysine in the histone - activates the chromatin allowing genes to be transcribed
What is histone methylation and its effect?
adding a methyl group to a lysine in the histone
depending on lysine position, methylation may cause inactivation/activation of the region of DNA
