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12 Cards in this Set
- Front
- Back
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what is gene expression? |
the overall process by which genetic information flows from genes to protein. it makes it possible for cells to produce specific proteins when and where they're needed |
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what is the promoter? |
site where transcription enzyme (RNA polymerase) attaches and initiates transcription |
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what is an operator and its function? |
An operator is a DNA control sequence. It acts as a switch and determines whether RNA polymerase can attach to the promoter and start transcription of the genes. |
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What is an operon? |
a cluster of genes w/ related functions (this includes the control sequences; exists only in prokaryotes) |
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what are histones? |
small proteins that attach to the DNA double helix |
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what is epigenetic inheritance? |
inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence —> such as the methylation of histone proteins or x chromosome inactivation |
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what are the steps in initiating gene transcription? |
1. activator proteins binds onto DNA control sequences called enhancers (enhancers are usually located far away on the chromosome from the gene they help regulate) 2. DNA-bending protein brings the activator protein closer to the promoter 3. the activator interacts with other transcription factor proteins, which then bind as a complex at the gene's promoter. this whole process allows for the correct attachment of RNA polymerase to the promoter and the initiation of transcription. This process needs to occur to get the RNA strand |
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what are microRNAs (miRNAs) and what do they do? |
small RNA molecules that can bind to complementary sequences on mRNA molecules. miRNAs form a complex with proteins, and this complex can bind to any mRNA molecule with 7-8 nucleotides of complementary sequences. Once bound, the complex either degrades this part of the mRNA or blocks its translation. Doing this regulates gene expression |
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A procedure called RNA interference (RNAi) |
injecting miRNA into a cell can turn off expression of a gene with a sequence that matches the miRNA |
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even after mRNA is fully processed and sent to the cytoplasm, it can still be regulated through: breakdown of mRNA, initiation of translation, protein activation, and protein breakdown. Explain each process. |
mRNA breakdown: enzymes in the cytoplasm eventually break down mRNA initiation of translation: controls the start of protein synthesis/won't start translation because the needed components are unavailable. protein activation: after translation, some polypeptides need to be modified in order to function, such as needing to cut the polypeptide to get a smaller product that is the active protein protein breakdown: selective breakdown of proteins (this is post-translation); this allows for a cell to adjust what kinds + how much protein it needs, in response to environmental changes. It allows a cell to maintain its proteins in prime working order |
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how does a proto-oncogene become a cancer-causing oncogene? |
oncogenes come from a genetic change that leads to an increase either in the amount of the proto-oncogene's protein product or in the activity of each protein molecule. |
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what is the use of tumor suppressor genes? |
the protein they encode prevents uncontrolled cell growth. they are genes that normally inhibit cell division. |
