6.5 Eukaryotic Gene Expression Flashcards
How is the phenotype of a cell or organism determined?
- by a combination of genes that are expressed, and the levels that they are expressed
What is it called when there are differences between cell type?
Differential gene expression
What are the 5 stages in which eukaryotic gene expression CAN be regulated at?
- Chromatin structure
- Epigenetic inheritance
- transcription initiation
- RNA processing
- Translation initiation
How can eukaryotic gene expression be regulated in chromatin structure?
- think of it as a spool and thread
- if DNA is tightly wound, it is less accessible for transcription
In regards to chromatin structure, how can a tightly wound DNA be modified to make it more accessible for transcription?
- Histone acetylation
2. DNA Methylation
What occurs in histone acetylation?
- adds acetyl groups to histones, which loosens the DNA
What occurs in DNA methylation?
- adds methyl groups to DNA, which causes the chromatin to condense
What is euchromatin? (2)
- DNA that is loosely packed and available for transcription
- done by histone acetylation
What is heterochromatin?
- DNA that is tightly coiled around histones and unavailable for transcription
- done by DNA methylation
What occurs in epigenetic inheritance? (2)
- chromatin modifications don’t alter the nucleotide sequence of DNA
- but the modifications can be heritable to future generations
In epigenetic inheritance, can modifications be reversed? What does this explain in terms of twins?
- modifications can be reversed, unlike mutations
- explains why one identical twin may inherit a disease while the other doesn’t
What occurs in transcription initiation?
- since chromatin modifications allow DNA to be more accessible, specific transcription factors bind to CONTROL ELEMENTS
what are control elements?
- sections of non coding DNA that serve as binding sites
Why are control elements essential?
- Gene expression can be increased or decreased
by binding of activators or repressors to control elements.
What is RNA splicing?
- alternative splicing of pre-mRNA
