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48 Cards in this Set
- Front
- Back
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What is mRNA? |
Messenger RNA; codes for proteins |
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What is rRNA? |
Ribosomal RNA; forms the core of the ribosome structure and catalyzes protein synthesis |
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What is tRNA? |
Transfer RNA; serves as adaptors between mRNA and amino acids during protein synthesis |
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What is the start codon? |
AUG |
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What are the stop codons? |
UAG, UAA, UGA |
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What does it mean when a tRNA is activated or charged? |
There is an amino acid attached |
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Where are the amino acids bound to the tRNA? |
2' or 3' OH |
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What is the common shape we see for tRNA? |
Clover leaf |
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What does it mean that tRNAs are isoaccepting? |
One tRNA can use the wobble position to provide the amino acid for more than one codon |
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What is aaRS? |
Aminoacyl tRNA synthetase; enzymes that add amino acids to tRNA |
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What are the two classes of aaRS? |
Class I adds to 2' OH Class II adds to 3' OH |
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What units make up the 70s subunit of the ribosome? |
50s and 30s |
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What are the 3 sites on a ribosome? |
E, P, A |
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What does the 16s subunit do? |
- scaffold for protein binding - 30s - 50s and tRNA interaction - anti shine delgarno |
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What does the 23s subunit do? |
- scaffold for protein binding - 30s - 50s and tRNA interaction - catalyzes peptide bond formation - ribozyme - allows easy movement of hydrophobic protein residues |
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What is the shine delgarno sequence? |
- 3-10 nucleotides long - 16 nucleotides upstream of AUG start site - one for each translation site (polycistronic) |
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What is the equivalent of the shine delgarno sequence in eukaryotes? |
Kozak consensus sequence |
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What binds UAA and UAG in prokaryotes? |
RF-1 |
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What binds UAA and UGA in prokaryotes? |
RF-2 |
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What binds GTP in prokaryotes? |
RF-3 |
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What is the preferred carbon source for E. coli? |
Glucose |
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What is beta gal? |
Breaks down lactose |
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What is the lacI repressor? |
- tetramer - binds 2 operators - causes kinks in DNA between operators |
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What does lactose do in the lac operon? |
Induces transcription by removing negative control |
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How long are primers? |
10 ribonucleotides |
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What are the lengths of Okazaki fragments? |
1000-2000 in prokaryotes and 100-200 in eukaryotes |
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What removes primers? |
DNA pol I/Ribonuclease H |
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What does ligase do? |
Closes gap in the sugar phosphate backbone between DNA and RNA primer |
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What is another name for helicase? |
DnaB |
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What is helicase's inhibitor? |
DnaC |
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What is topoisomerase? |
Relieves twisting forces |
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What are SSBs? |
Single strand binding proteins; stabilizes single strands |
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What is the sliding clamp? |
Holds DNA pol III in place |
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What does telomerase do? |
Adds additional repeats to the template strand so that the ends of the DNA strands can be replicated |
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What are telomeres? |
Repeated sequences at the end of chromosomes |
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Why can proofreading not occur 3' to 5'? |
If a base is removed, there would be no energy source from phosphate to continue elongation |
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What are the steps in DNA replication? |
- binding of initiator protein to replication origin - binding of helicase to initiator protein - loading of helicase onto strand - helicase opens helix and binds primase - RNA primer synthesis enables DNA polymerase to start first DNA chain - formation of replication forks |
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What is inducible negative control? |
Ligand binds to a repressor protein, allowing transcription to occur |
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What is repressible negative control? |
Ligand binds to a protein, blocking transcription from occurring |
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What does CAP stand for? |
Catabolite activator protein |
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What is CAP? |
Binds the CAP site when itself bound by cAMP |
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What inhibits cAMP formation? |
Glucose |
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What is inducible positive control? |
Activator protein must be bound to the gene after being found by a ligand |
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What is repressible positive control? |
Activator is usually bound and requires a ligand to detach |
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Low glucose + lactose available = |
Lac genes strongly expressed |
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High glucose + lactose unavailable = |
Lac genes not expressed |
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Low glucose + lactose unavailable = |
Lac genes not expressed |
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High glucose + lactose available = |
Very low level of gene expression |
