Term
| What makes up a ribosome? |
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Definition
| 1 large subunit, 1 small subunit |
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Term
| What is contained in each ribosomal subunit? |
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Definition
| Proteins, at least 1 rRNA |
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Term
| What are the large and small prokaryotic subunits? |
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Definition
Large: 50S; has 23+5 rRNAs
Small: 30S; has 16S rRNAs |
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Term
| What are the large and small eukaryotic subunits? |
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Definition
Large: 60S; has 28S, 5.8S, 5S rRNAs
Small: 40S; has 18S |
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Term
| Where are eukaryotic rRNAs synthesized, and by what enzyme? |
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Definition
| In the nucleolus, by RNA polymerase 1 |
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Term
| Which rRNA portion is NOT transcribed in the nucleolus? |
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Definition
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Term
| How are ribosome subunits assembled in eukaryotes? |
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Definition
| Combine the processed rRNAs with ribosomal subunits from the cytoplasm |
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Term
| What are the three tRNA binding sites of ribosomes? |
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Definition
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Term
| What do A, P, and E stand for (on the tRNA binding sites) |
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Definition
Acceptor
Peptidyl transferase
Exit site |
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Term
|
Definition
A site: binds incoming aminoacyl tRNA
P site: binds tRNA to growing polypeptide chain
E site: where uncharged tRNA exits |
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Term
| What enzyme transcribes tRNA? |
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Definition
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Term
| What is tRNA charging and what enzyme catalyzes the reaction? |
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Definition
| Linking specific amino acids to specific tRNAs, done by aminoacyl-tRNA synthetases |
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Term
| What is linked to the 3' end of the tRNA? |
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Definition
| the carboxyl-terminus of amino acid |
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Term
| What are the three stages of prokaryotic translation? |
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Definition
| Initiation, Elongation, Termination |
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Term
| What is the Shine Delgarno sequence? |
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Definition
|
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Term
| What is the function of the Shine-Delgarno sequence? |
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Definition
| It allows the 30S subunit to bind mRNA to a complementary sequence on the 16S rRNA |
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Term
| Where is the AUG start codon found? |
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Definition
| 7 nucleotides downstream of the SD sequence |
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Term
| Where is the AUG start codon alligned? |
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Definition
| With the P site of the small subunit |
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Term
| What does the IF2-GTP complex do? |
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Definition
| It binds methionyl-tRNAfmet |
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Term
| After tRNAfmet binds in the P site, what happens? |
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Definition
| Initiation factors are released and the large subunit (50S) binds the small subunit (30S) |
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Term
| What happens in elongation? |
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Definition
- Specific aminoacyl tRNA binds to A site with EF-TU-GTP
- Peptide bond forms b/w amino acids on the tRNA
- A site breaks the bond between the amino acid and tRNA in the P site |
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Term
| True or False: Breaking the bond b/w the amino acid and tRNA in the P site requires ATP |
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Definition
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Term
| In what direction does the ribosome move during elongation? |
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Definition
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Term
| What is required for ribosome movement? |
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Definition
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Term
| When does elongation stop? |
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Definition
| When it reaches a stop codon in the A site |
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Term
| What happens in termination? |
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Definition
- Release factor 1 or 2 binds to a stop codon
- p.p. chain is released from the tRNA in the P site
- mRNA is released
- Ribosome subunits dissociated |
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