The UG4 gene is expressed in stem tissue and leaf tissue of the plant Arabidopsis thaliana. To study mechanisms regulating UG4 expression, six small deletions of DNA sequence upstream of the gene-coding sequence are made. The locations of deletions and their effect on UG4 expression are shown here. Why does deletion D raise UG4 expression in leaf tissue but not in stem tissue?

Key Concepts

Gene Regulation

Gene regulation refers to the mechanisms that control the expression of genes, determining when and how much of a gene product is produced. This can involve various elements such as promoters, enhancers, and silencers, which interact with transcription factors to modulate gene activity. Understanding these regulatory elements is crucial for interpreting how specific deletions can affect gene expression in different tissues.

Tissue-Specific Expression

Tissue-specific expression is the phenomenon where certain genes are expressed in specific tissues or developmental stages of an organism. This is often regulated by the presence of unique transcription factors or regulatory elements that are active only in those tissues. In the case of the UG4 gene, its differential expression in leaf versus stem tissue suggests that distinct regulatory mechanisms are at play in these tissues.

Deletion Mutations

Deletion mutations involve the removal of a segment of DNA, which can impact gene expression by altering the regulatory regions that control transcription. Depending on the location and size of the deletion, it can either enhance or repress gene expression. In this scenario, understanding how deletion D affects the regulatory landscape upstream of the UG4 gene is key to explaining its increased expression in leaf tissue.