3.8.2.2 Regulation of transcription and translation Flashcards
What is the role of specific transcriptional factors in eukaryotic transcription?
Specific transcriptional factors stimulate or inhibit the transcription of target genes by moving from the cytoplasm into the nucleus where they bind to specific DNA sequences near the gene promoter.
How does oestrogen initiate transcription?
Oestrogen binds to an oestrogen receptor forming an oestrogen-receptor complex. This complex acts as a transcription factor by binding to specific DNA sites near target genes stimulating transcription.
What is epigenetics?
Epigenetics involves heritable changes in gene function without alterations to the base sequence of DNA often influenced by environmental factors.
How does increased DNA methylation inhibit transcription?
Increased methylation of DNA occurs at cytosine bases and prevents transcription factors from binding to the DNA thereby inhibiting transcription.
How does decreased acetylation of histones inhibit transcription?
Decreased acetylation increases the positive charge on histones strengthening their association with DNA making the chromatin more condensed and less accessible to transcription factors thereby inhibiting transcription.
What is the relevance of epigenetics in the development of cancer?
Epigenetic changes such as hypermethylation of tumour suppressor genes or hypomethylation of oncogenes can lead to uncontrolled cell division and cancer development.
How can epigenetic changes be targeted in disease treatment?
Drugs can be used to reverse epigenetic changes such as DNA methylation inhibitors or histone deacetylase inhibitors which can reactivate silenced genes.
What is RNA interference (RNAi)?
RNA interference (RNAi) is a process where small RNA molecules such as siRNA or miRNA bind to complementary mRNA molecules preventing their translation and thereby inhibiting gene expression.
How does siRNA inhibit translation?
siRNA forms a complex with proteins binds to complementary mRNA and induces its degradation preventing translation.
How does miRNA inhibit translation?
miRNA binds to target mRNA molecules often partially complementary and inhibits their translation by blocking ribosome attachment or causing mRNA degradation.
How can data be interpreted to investigate gene expression?
Data interpretation may involve identifying changes in gene expression levels through techniques such as qPCR assessing the effects of transcriptional factors or analysing the impact of epigenetic modifications.
How can data be evaluated for genetic vs environmental influences on phenotype?
Evaluation involves comparing phenotypic data from genetically identical individuals in different environments statistical analysis of heritability or examining epigenetic changes linked to environmental factors.
