First Aid: Biochemistry - Molecular Day 1
Terms
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- What histone octamers is DNA looped twice around?
- H2A, H2B, H3, H4 (nucleosome bead)
- What ties nucleosomes together in a string?
- H1
- Heterochromatin is transcriptionally (inactive/active)
- Inactive (condensed)
- Euchromatin is transcriptionally (inactive/active)
- Active (less condensed)
- What are purines; how many rings
- A, G (2 rings)
- What are pyrimidines; how many rings
- C, T, U (1 ring)
- nucleotides linked by what bond
- 3'-5' phosphodiesterase bonds
- what is transversion?
- purine for pyrimidine, or pyrimidine for purine
- what is transversioni
- purine for pyrimidine, or vice versa (different type)
- 4 features of genetic code
- unambiguous, degenerate, commaless/nonoverlapping, universal
- silent mutation
- same aa, often base change in 3rd position of codon
- missense
- changed aa
- nonsense
- changed aa resulting in early STOP codon
- frame shift
- change resulting in misreading of all nucleotides downstream
- Prokaryotes have (single/multiple) origins of replication
- single
- what is transition?
- purine for purine, or pyrimidine for pyrimidine (same type)
- fxs of RNA pol I, II, III (eukaryotes)
- I -> rRNA, II -> mRNA, III -> tRNA
- What inhibits RNA pol II
- alpha-amanitin (in death cap mushrooms)
- how many RNA pol in prokaryotes
- one (makes all 3 kinds of RNA)
- mRNA initiation codon
- AUG (inAUGurates); for met or f-met
- stop codons
- UGA (U Go Away), UAA (U Are Away), UAG (U Are Gone)
- what are regulators of gene expression
- promoter, enhancer, operator
- fx of promoter
- where RNA pol and multiple transcription factors bind to DNA (upstream of gene locus)
- fx of enhancer
- alters gene expression by binding transcription factors (close to, far from, or within gene)
- fx of operator
- where negative regulators (expressors) bind
- fx of exons
- actual genetic info for protein
- fx of introns
- noncoding segments of DNA
- what is splicing
- removal of introns from primary mRNA transcripts
- what binds to primary mRNA transcripts and forms spliceosomes
- snRNP
- Steps in RNA processing
- Capping on 5' end, polyadenylation on 3' end, splicing out of introns
- Initial transcript is called ___; capped and tailed transcript is called ___
- hnRNA, mRNA
- All tRNAs have ___ at 3' end along with a high percentage of chemically modified bases
- CCA
- The AA is covalently bound to the __' end of the tRNA
- 3'
- this enzyme adds AA to tRNAs
- Aminoacyl tRNA synthetase
- A ___ tRNA reads usual codon but inserts wrong AA
- mischarged
- what is tRNA wobble
- codons may differ in 3rd "wobble" position but still code for same tRNA/AA