Term
| What is the ribosome like? |
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Definition
| There are several subunits which come together. The 40S +60s, for example, make the 80s subunit, but there is also another subunit. The s stands for how it responds to centrifugation. |
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Term
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Definition
| These are TLN initiation factors. There are alot of these (like 13?) |
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Term
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Definition
| TLN elongation factors. There are only about 3 of these. |
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Term
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Definition
| Release factors. There is only one of these known. |
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Term
| What is the thing that brings in the amino acid? |
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Definition
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Term
| What does tRNA have on the inside that gets the right amino acid to the right spot on the nascent peptide? |
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Definition
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Term
| How many amino acids are there? How many codons are there? What does this mean? |
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Definition
| 20 AA's. 64 codons. This means you can fu...never mind. It means that there are alot of codons for different AA's, but the codons do actually act a little differently even though they get the same AA. |
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Term
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Definition
| Wobble happens with arginine. Perfect base pairing is required only for the first 2 bases of the codon, but the last one can be anything. |
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Term
| What tRNA does initiation? Is it special? |
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Definition
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Term
| What is it called when a tRNA has an AA attached to it? |
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Definition
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Term
| Is the adding of an amino acid to a tRNA catalyzed? If so, by what? |
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Definition
| Yes, but aminoacyl tRNA synthases (one for each tRNA) |
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Term
| How does the AA attach to the tRNA? |
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Definition
| Amino acid gets activated by having AMP attached (was ATP and then pyrophosphate got released). Then it can attach. Once it attaches, it gives away the AMP. |
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Term
| What are the 3 binding sites of the ribosome? What do they do? |
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Definition
| A, P, E. A site binds aminoacyl-tRNA. P binds a peptidyl-tRNA (like the tRNA attached to the nascent peptide). E site binds the free tRNA before it is released. |
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Term
| What does the 7 methyl-guanosine cap do? |
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Definition
| This is the 5' cap. This is where the ribosome attaches and then scans until it finds the start codon. |
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Term
| What is the start codon? Can anything with these letters be a start codon? |
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Definition
| AUG is the start codon, but not anything is a start codon. Has to have a consensus sequence around it and other stuff. |
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Term
| At the initiation of translation, what is in the P site of the ribosome? |
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Definition
| met-tRNA is in the P site, because this is special met-tRNA. You still get a start codon after scanning. |
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Term
| When does eIF2-GTP bind? What happens to it after? |
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Definition
| eIF2-GTP binds the 40s subunit during the initiation process. When the ribosome finds the start codon, GTP is hydrolyzed to GDP and eIF2 falls off. Then the 60s subunit binds. |
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Term
| what is bound to the charged tRNAs? What's with that? What has to happen to it? |
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Definition
| eEF1A-GTP is bound, but it has to leave for the peptide bond to form. But it has to be eEF1A-GDP to leave. SO, need a special protein to do that. |
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Term
| What protein hydrolyzes GTP on eEF1-A? Why is this important? What determines whether this enzyme will work? |
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Definition
| The GAP protein hydrolyzes eEF1A-GTP to eEF1A-GDP. This allows the tRNA to bind the A site. The longer the tRNA sits in the A site, the greater chance that the GAP will come in and do its job. This is why codon-anticodon interactions determine what AA gets attached (good codon-anticodon interaction makes for longer sitting in the A site) |
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Term
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Definition
| They regenerate eEF1A-GDP to eEF1A-GTP |
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Term
| What kind of bond forms between two AA's? How does it happen? What kind of enzyme does it? |
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Definition
| You get a peptide bond. This is called a peptidyl transferase reaction and is catalyzed by a ribozyme. The tRNA falls off as this happens. The first AA is almost always MET. |
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Term
| After a peptide bond forms, what happens? |
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Definition
| So, the tRNA separates from the AA and moves to the E site. The previous charged tRNA is now in the P site and a peptide bond forms. A new tRNA comes into the A site. |
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Term
| What provides the energy for movement of the ribosome? |
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Definition
| hydrolysis of eEFG2-GTP to GDP. |
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Term
| What are polysomes? Why are they important? |
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Definition
| Elongation rate of translation is only about 13aa per second. SO, get multiple ribosomes attaching to the RNA at once. These ribosomes make different copies of the same protein. they DO NOT work on the same copy of the protein, beotch. |
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Term
| What is the proofreading mechanism involving amino acids and tRNA? |
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Definition
| Aminoacyl tRNA synthase makes sure it adds the right aa to the right tRNA codon. Mistakes do happen, but only 1 per 10^4 |
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Term
| How does translation termination happen? How does a stop codon actually work? |
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Definition
| Stop codon signals gene end. (Stop codon signals no specific tRNA, so nothing else gets added.) When a stop codon is in the A site, eRF binds and the finished protein is hydrolyzed from the last tRNA. Ribosomal subunits dissociate. |
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Term
| Why would targeting bacterial translation be useful? |
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Definition
| Antibiotics can stop bacteria from living haha |
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Term
| In response to stress, what does PKR do? |
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Definition
| protein kinase R phosphorylates eEIF2-GTP to eIF2-GDP. This means that the initiation complex of met-tRNA and the ribosome cant come together! |
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Term
| Talk about RNA interference. |
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Definition
| micro RNAs are small dsDNAs which act as transcriptional repressors. They work with RISC complex to bind to and cleave complimentary mRNA sequences. |
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Term
| At what level does RNA interference work? |
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Definition
| post-transcriptional. pre translational. |
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Term
| What kind of RNAs that do interference are exogenous? |
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Definition
| siRNAs come from viruses. |
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Term
| How does HIV get alot of proteins out of a genome? |
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Definition
| Frameshifting. Intentionally. |
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Term
| What protein is involved with preparing miRNA for action? |
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Definition
| Dicer chops it up in the right places. |
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