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27 Cards in this Set
- Front
- Back
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RNA differences |
-2' carbon has an hydroxyl group instead of 2 Hydrogens -uridine takes place of thymine -unstable |
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MRNA |
Intermediaries that carry genetic information from DNA to the ribosomes |
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TRNA |
Adapters between amino acids and the codons in mRNA |
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RRNA |
Structural and catalytic components of ribosomes |
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SnRNA |
Structural components of spliceosomes |
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MiRNA |
Short single-stranded RNAs that block expression of complementary mRNAs |
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Prokaryote transcription |
The mRNA codon on the mRNA are translated into an amino acid sequence by the ribosome |
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Eukaryotes Transcription |
-The primary transcript is a precursor to the mRNA -The pre-mRNA is modified at both ends and Intron's are removed to produce the mRNA -after processing, the mRNA is exported to the cytoplasm for translation by ribosomes |
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Template strand |
DNA strand that is copied via complementary base pairing during transcription |
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Non template strand |
DNA strand that is not used during transcription -has the same sequence as that RnA copy |
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Synthesis |
The replacement of the three prime hydroxyl with a phosphodiester linkage synthesis is five prime to three |
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Upstream Sequences |
Bases preceding the initiation site (-) To the left of the promoter |
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Initiation in Prokaryotes |
1. Binding of RNA polymerize to a promoter region in DNA 2. Localized unwinding of the two strands of DNA by RNA polymerize to provide a single-stranded template 3. Formation of phosphodiester bonds between the first few ribonucleotide's in the Nascent RNA chain |
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Sigma factor |
The addition of the sigma factor subunit allows initiation at promoter sites |
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Prokaryote Elongation |
1. One DNA strand used as template for RNA synthesis 2. RNA is synthesized five prime to three prime direction 3. Genes can be encoded on different DNA strands |
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P-independent termination |
1. Template strand contains: inverted repeats followed by a track of 6 A nucleotides 2. RNA polymerase transcribes template strand 3. Inverted repeats hydrogen bond forming hairpin structure 4. When are in a polymerize encounters hairpin it will pause 5. Weak hydrogen bonds between A's that follow and the U's in the newly synthesized strand will break, releasing transcript from DNA |
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Rho-dependent termination |
1. Rho binds 50-90bp region of transcript with many C's and no secondary structure 2. Rho follows RNA pol along transcript 3. Rna pol pauses at termination site (sometimes a hairpin) 4. Rho catches up and uses its helicase activity to unwind the DNA-RNA base pairs, releasing the transcript |
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Eukaryotic Transcription |
1. Have more diverse promoters 2. Have three different RNA polymerase a 3. Require RNA processing of primary mRNA transcript to produce mRNA |
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RNA polymerase II |
-recognizes and binds to promoter sequences with the aid of transcription factors - |
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TFII |
Transcription factors that bind to regulatory sequences and interact directly or indirectly with RNA polymerize two |
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Initiation Eukaryotes |
-begins when the TF11D binds to the TATA box - |
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Enhancers |
-When promoters alone are not sufficient to initiate transcription, these guys are called in -promotes transcription of a gene by stabilizing transcription initiation complex at promoter -bind activator proteins to form a protein bridge that links the proteins at the enhancer sequence to the initiation complex at the promoter -the bridge bends the DNA so that the proteins at both locations are brought close enough to interact |
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MRNA processing in eukaryotes |
Addition of 5' cap Addition of poly-A tail 3' Splicing out introns |
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Function of 5' cap |
-protection of mRNA from rapid degradation -enhancing translation efficiency by orienting the ribosome on the mRNA -facilitating subsequent intron splicing -Facilitating transport of mRNA out of the nucleus |
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Function of polyadenylation |
Facilitating transport of mature mRNA across the nuclear membrane to the cytoplasm |
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R-Loop Hybridization |
-seven DNA introns produce unpaired loops -the loops are formed because they contain introns, which can't pair with the mature mRNA -excision of intron sequences must be precise |
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Mutation and splicing |
Mutations can create novels splice sites where they don't belong and disrupt a normal splicing signal that can cause inclusion of Introns |
