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9 Cards in this Set
- Front
- Back
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In bacteria the genes encoding ribosomal RNA, tRNA, and mRNA are transcribed by different RNA polymerases
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False. Bacteria have only one RNA polymerase that transcribes all genes; in contrast, eukaryotic cells have three different polymerases, each dedicated to one of the three classes of genes.
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In bacteria, but not in eukaryotes, most mRNAs encode more than one protein
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True. Prokaryotic mRNAs are often transcripts of entire operons. Ribosomes can initiate translation at internal AUG start sites of these "polycistronic" mRNAs.
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Most DNA-binding proteins bind to the major groove of the double helix.
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. The major groove of double-stranded DNA is sufficiently wide to allow a protein surface, such as one face of an helix, access to the base pairs.
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Of the major control points in gene expression (transcription, RNA processing, RNA transport, translation, and control of a protein's activity), transcription initiation is used for the vast majority of gene regulation events.
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True. It is advantageous to exert control at the earliest possible point in a pathway. This conserves metabolic energy because unnecessary products are not made in the first place.
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The zinc atoms in DNA-binding proteins that contain zinc finger domains contribute to the binding specificity through sequence -specific interactions, that they form with the bases.
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False. The zinc atoms in zinc finger domains are required for the correct folding of the protein domain; they are internal to these domains and do not contact the DNA
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Lipids in a lipid bilayer rotate rapidly around their long axis
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True
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Lipids in a lipid bilayer rapidly exchange positions with one another in the plane of the membrane.
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True
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Lipids in a lipid bilayer do not flip-flop readily from one lipid monolayer to the other.
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True
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hydrogen bonds that form between lipid head groups and water molecules are continually broken and re-formed
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True
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