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BIOL211:CH18
CH18 - Control of Gene Expression in Eukaryotes
| Question | Answer |
|---|---|
| An enhancer is _____. | A coding region of DNA that may be located within an intron. Enhancers, which increase gene transcription, can be located upstream or downstream of the gene and within introns. |
| can eukaryotic regulatory sequences function if their 5’ to 3’ orientation is reversed? | yes |
| Why does DNase cut only transcriptionally active genes? | because DNA wrapped around histones is protected from degradation by nucleases. |
| What effect do histone deacetylases have on chromatin structure? | Histone deacetylases remove acetyl groups from histones and make them more positively charged. |
| Where is a eukaryotic promoter found and what does it contain? | Eukaryotic promoters are always found upstream of the gene and almost always contain the TATA sequence (TATAAA) to which the TATA binding protein binds. |
| Which proteins have analogous functions in eukaryotes and in E. coli? | TATA binding protein and sigma protein |
| All eukaryotic promoters are bound by which protein that is involved in the initiation of transcription of mRNA in eukaryotes? | TATA binding protein |
| What is the significance of splicing patterns in mRNA? | Splicing patterns in mRNA are critical to protein formation. Differences in post-transcriptional splicing patterns can result in the formation of different proteins or significant changes in the conformation of the protein produced. |
| In smooth and striated muscle cells the DNA for tropomyosin is the same, yet the mRNAs produced are different. Which of the following statements explains this phenomenon? | The splicing patterns of the mRNA in the two cells differ, most likely due to differing conditions within the two cell types. The presence of cell-type-specific compounds influences the splicing patterns of the mRNA. |
| The life span of an mRNA molecule can be controlled by the activities of _____. | The RISC protein complex, which binds 22bp single-stranded RNA and assists this fragment to bind to its complementary mRNA; this binding triggers another enzyme to degrade the mRNA. |
| What does p53 protein do? | It is a TUMOR SUPPRESSOR; a regulatory transcription factor that activates transcription of cell cycle control genes. It activates genes that induce apoptosis in cells with extensively damaged DNA. |
| CHROMATIN is made of what components? | DNA+proteins (histones) |
| These ___ acetylate chromatin and these ____ deacetylate chromatin. | HATs: histone acetyl transferases add negatively-charged acetyl groups to chromatin. HDAC's: histone deacetylases: remove acetyl groups from chromatin, making it more positively charged. |
| Why is insulin is made in our pancreas and not in other cells? | Because the specific TRANSCRIPTION FACTORS for insulin production are present only in the pancreas. In pancreas cells, the DNA is "open" for the promoter to bind and transcription to begin. |
| What is BASAL TRANSCRIPTION MACHINERY and what does it do? | It is a protein complex that binds to promoter for eukaryotic TRANSCRIPTION INITIATION (Step 1) |
| What are ENHANCERS and how do they work in eukaryotic TRANSCRIPTION INITIATION? | enhancers are DNA sequences; they are regulatory elements that are far from the promoter that stimulates the activity of the promoter when t.f.s. bind to them |
| What are the DNA sequences that do the opposite of ENHANCERS? | SILENCERS: they slow down the rate of transcription when protein binds to them |
| In TRANSCRIPTION INITIATION, what happens next, after the BASAL TRANSCRIPTION MACHINERY binds do the PROMOTER? | (step 2) TATA box binding protein (TBP: "TATA box binding protein" binds to TATA box) |
| In TRANSCRIPTION INITIATION, what happens next, after TATA box binding protein binds to the TATA box? | (step 3) transcription factors (proteins): they bind to ENHANCER |
| In TRANSCRIPTION INITIATION, what happens next, after t.f.'s bind to ENHANCER? | (step 4) RNA polymerase binds to the complex of basal t.f. and promoter and starts Transcription. |
| What are the 2 domains of the REGULATORY TRANSCRIPTION FACTORS? | 1. regulatory domain: binds to other proteins in the basal t.c. complex or other proteins such as coactivators 2. recognition domain: the part of the regulatory TFs that binds to DNA (making direct contact w DNA) |
| In this level of gene expression control, the PRIMARY TRANSCRIPT undergoes splicing of various exons, resulting in a possible estimated 100K proteins from 20K human genes. | ALTERNATIVE SPLICING |
| What is miRNA? | small single-stranded RNAs called micro RNAs (miRNAs). miRNA is another way of controlling gene expression via controlling mRNA stability or the translation of mRNAs. |
| What is RNA INTERFERENCE? | It is a mechanism to control the expression (translation) of RNA. it blocks protein formation by blocking translation or making mRNA subject to degradation by other enzyme. |
| What is the RISC protein complex? | TBD |
| Define the OPERON and describe its relevance to eukaryotes. | In the OPERON, several different structural genes are under the regulation of single promoter. Is in bacteria and is rare in eukaryotes. |
Created by:
boborii
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