All Flashcards
Define regulatory sequences.
DNA sequences that control gene expression by increasing or decreasing transcription; located near promoter regions.
What is the definition of enhancers?
Regulatory sequences that increase transcription.
What is the definition of silencers?
Regulatory sequences that decrease transcription.
Define epigenetic changes.
Heritable changes in gene function without altering the DNA sequence itself.
What is DNA methylation?
The addition of a methyl group to a DNA base, typically cytosine, leading to gene repression.
What is histone modification?
Changes to the structure of histone proteins, such as acetylation or methylation, that alter chromatin structure and affect DNA accessibility to transcription machinery.
Define phenotype.
The observable characteristics of a cell or organism, determined by gene expression.
What is cell differentiation?
The process by which different cell types acquire distinct functions and characteristics through differential gene expression.
Define operons.
Groups of genes transcribed together into a single mRNA molecule, controlled by a single promoter (primarily in prokaryotes).
Define coordinated regulation.
Groups of genes controlled together for efficient expression of genes involved in the same cellular process.
Differentiate between enhancers and silencers.
Enhancers: Increase transcription. Silencers: Decrease transcription.
What are the differences between DNA methylation and histone acetylation?
DNA Methylation: Generally represses gene expression. Histone Acetylation: Generally promotes gene expression.
Compare and contrast the lac and trp operons.
lac operon: inducible, activated by lactose. trp operon: repressible, repressed by tryptophan.
Differentiate between genotype and phenotype.
Genotype: Genetic makeup. Phenotype: Observable traits resulting from gene expression.
Compare gene regulation in prokaryotes and eukaryotes.
Prokaryotes: Primarily operons. Eukaryotes: Transcription factors and epigenetic modifications.
Compare the roles of activators and repressors in transcription.
Activators: Increase transcription by aiding RNA polymerase binding. Repressors: Decrease transcription by blocking RNA polymerase binding.
What happens when DNA is methylated?
Gene expression is typically repressed.
What is the effect of histone acetylation?
Increased gene expression due to relaxed chromatin structure.
What happens when lactose is present in the lac operon?
The repressor protein is inactivated, allowing transcription of the lac operon genes.
What is the effect of low glucose levels on the lac operon?
CAP protein binds to the promoter, enhancing RNA polymerase binding and increasing transcription.
What happens when tryptophan levels are high in the trp operon?
The trp operon is turned off, preventing further tryptophan synthesis.
What is the effect of mutations in regulatory sequences?
Can lead to dysregulation of gene expression and diseases, including cancer.