Lecture 17 Flashcards
What is the difference between structural genes and regulatory genes?
Structural Genes: Encoding proteins
Regulatory Genes: Encoding products that interact with other sequences and affect the transcription and translation of these sequences
What is the significance of DNAse 1 sensitivity?
These hypersensitive sites are a more open chromatin configuration site, upstream of the transcription start site
What is the structural significance of repressors?
Bind to silencers to prevent transcription
What is the structural significance of enhancers?
DNA sequence stimulating transcription a distance away from promoter
What is the structural significance of insulators?
DNA sequence that blocks or insulates the effect of enhancers
What are DNA binding proteins and how are they categorized?
Proteins that bind to DNA to aid the transcription of certain genes; categorized according to the motif of the proteins
Explain CHIP and how it is used for identifying DNA/protein interactions
Can be used to identify DNA-binding sites of a specific protein and the locations of modified histone proteins
- DNA and associated proteins on chromatin are crosslinked
- DNA-protein complexes are sheared into 500 bp DNA fragments by sonification or nuclease digestion
- Cross-linked DNA fragments associated with the proteins of interest are selectively immunoprecipitated from the cell debris using an appropriate protein-specific antibody
- Associated DNA fragments are purified and their sequence is determined; enrichment of specific DNA sequences represents regions on the genome that the protein of interest is associated with in vivo
What is the significance of alternative splicing?
In the T-antigen gene, it leads to the production of the small t antigen and the large t antigen in response to the mammalian virus SV40; can also lead to the formation of cancer in other genes; ultimately, leads to new proteins being made based on how the exons are spliced together
How are genes able to respond to multiple inducers (multiple response elements)?
When an inducer binds to its response element, that leads to the transcription
What is constitutive expression?
Continuously expressed under normal cellular conditions
What is positive versus negative control?
Positive Control: Stimulates gene expression
Negative Control: Inhibit gene expression
What is a motif?
Simple structure within the domain that fits into the major groove of the DNA; examples include helix-turn-helix, zinc fingers, and leucine zipper
What is a domain?
60-90 amino acids, responsible for binding to DNA, forming hydrogen bonds with DNA
How do amino acids in DNA-binding proteins interact with DNA?
By forming hydrogen bonds with DNA base
What are chromatin remodeling complexes?
Bind directly to DNA sites and reposition nucleosomes
What are mediators?
Multiprotein complex that functions as a transcriptional coactivator in all eukaryotes; main function of mediator complexes is to transmit signals from the transcription factors to the polymerase
