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28 Cards in this Set
- Front
- Back
3 Major Classes of RNA |
mRNA rRNA tRNA |
|
RNA Pol I |
Transcribes most rRNA genes |
|
RNA Pol II |
transcribes protein coding genes, miRNA, and various other small RNAs |
|
RNA Pol III |
Transcribes tRNA, 5S rRNA and various other small RNAs |
|
Structures on ends of Mature mRNA |
5' Cap (phosphorylated guanine) and 3' Poly A tail |
|
First Amino Acid in every peptide and codon |
Methionine AUG |
|
4 levels of gene expression control |
Transcriptional RNA processing RNA transport Translation |
|
Prokaryote mRNA features (4) |
No introns No 5' cap (just modifies methionine) No Poly A Tail More likely to be polycistronic |
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Direction of translation |
5' to 3' |
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3 Binding sites for tRNA in RNA Pol II |
A;P;E |
|
What do stop codons code for? |
Release Factor |
|
Charged tRNA |
has an amino acid at its 3' end |
|
Function of Aminoacyl-tRNA synthetases |
Adds amino acids to tRNA |
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When can Control of gene expression be regulated? (4) |
Transcription control RNA processing control RNA transport Control Translational control Post translational control |
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4 Methods of Transcriptional control |
Accessibility of the gene Gene silencing by DNA methylation Transcriptional activators/repressors Freqeuncy of transcription initiation. |
|
Nucleosome |
8 histone proteins (146 bp) |
|
Epigenetics |
Heritable changes in gene expression not caused by changes to DNA sequence |
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2 methods of epigenetic control |
DNA methylation Histone modification |
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DNA methylation |
on Cytosine Prevents transcription by attracting transcription blocker proteins or by blocking transcription factor binding |
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Histone acetylation |
switches on genes |
|
HAT enzymes |
Histone acetyl transferase add acetyl groups to histones |
|
HDAC enzymes |
Histone Deacetylases repress transcription |
|
HMT enzymes |
Histone Methyl transferase Involved in DNA methylation |
|
3 methods of transmitting expression patterns to daughter cells |
Positive feedback loop of transcription regulators Propagation of condensed chromatin structure Propagation of DNA methylation state |
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Combinatorial control of transcription |
Groups of regulatory proteins work together to express a gene |
|
Enzyme involved in gene splicing |
Spliceosome |
|
trp operon |
Tryptophan binds to inactive repressor which activates it Repressor then binds to operating preventing RNA Pol from binding |
|
lac operon |
Lactose binds to active repressor inactivating it allowing RNA pol to bind to promotor RNA Pol binding is stimulated by CAP which is activated by cAMP produced when glucose levels are low |