Unit 6: Topic 5 - Regulation of Gene Expression Flashcards
What are regulatory sequences?
Regulatory sequences are sequences of DNA that act as binding sites for regulatory proteins, which can promote or inhibit transcription.
What are epigenetic changes?
Epigenetic changes are reversible modifications to DNA or histones that affect gene expression without changing the DNA sequence. Epigenetic changes can be influenced by environment and, in some cases, inherited from parents.
Examples of epigenetic changes include DNA methylation and histone modification.
What is DNA methylation?
DNA methylation is when a methyl group is added to a specific places on the DNA, where it blocks the proteins and reduces gene expression for transcription.
What is histone modification?
Histone modification is when histones (proteins that DNA wrap around of) are tightly packed together, so the proteins cannot access the DNA (gene is turned off).
How is the phenotype of a cell or organism determined?
Although every cell in a multicellular organism contains the same DNA, the organism contain cells that look and function differently. The phenotype of a cell or organism is determined by the combination of genes that are expressed and the levels at which they are expressed.
What are factors that affect phenotypes of an organism at the cellular level?
- Observable cell differentiation results from the expression of genes for tissue-specific proteins.
- Gene regulation results in differential gene expression and influences both the proteins a cell produces and the cell’s function.
- Induction of transcription factors during developmental results in sequential gene expression.
What are transcription factor? How does induction of transcription factor work?
Transcription factors are proteins that regulate the transcription of genes. Transcriptional factor binding to the regulatory region of a gene induces or represses its gene expression. By binding to DNA at a specific target sequence, a transcription factor makes it harder or easier for RNA polymerase to bind to the promoter of the gene. https://cdn.kastatic.org/ka-perseus-images/6e36b83cfdb73e9c706f3b7bdeb71398d4d5badd.png
What are operons in prokaryotes? What are inducible operons and repressible operons?
Prokaryotes use operons to regulate gene expression. An operon is a group of related genes with a single promoter. The group of genes is transcribed into a single mRNA molecule.
Inducible Operons are usually off (structural genes not expressed), which means that repressor proteins are normally bounded to the operator of the operon and block transcription. Under certain conditions, an inducer binds to the repressor protein and causes it to change shape and unbind from the operator. Once the repressor protein is released from the operator, RNA polymerase transcribes the genes and they are expressed. An example of an inducible operon is the lac operon.
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The structural genes in repressible operons are usually expressed or on. This means that repressor proteins are normally not bound to the operator of the operon. Under certain conditions, a corepressor binds to the repressor protein and changes its shape so that it can bind to the operator and block the transcription and expression of the structural genes. An example of a repressible operon is the trp operon.
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In eukaryotes, how are groups of genes coordinately regulated?
Eukaryotic genes are controlled by sets of transcription factor, proteins that bind to specific DNA sequences in or near a gene and promote or repress its transcription into an RNA. In eukaryotes, groups of genes may be influenced by the same transcription factors to coordinately regulate expression.
