Flashcards in Biochem miscellaneous Deck (123)
exceptions to degeneracy of genetic code
methionine + tryptophan (each encoded by only 1 codon)
codon for methionine
codon for tryptophan
nucleotides methylated in replication
cytosine + adenine
how is uracil derived?
deamination of cytosine
what makes thymine unique?
Has a methyl grow.
when does NER occur?
sequence of events in base excision repair
glycosylase removes altered base and creates AP site --> AP endonuclease cleaves 5' end --> lyase cleaves 3' end --> pol fills gap --> ligase seals it
significance of N-formylmethionine (fMET)
- initiates protein synthesis in bacteria.
- Nucleic acid coded by start codon.
- Stimulates neutrophil chemotaxis.
describe mRNA quality control
Occurs at cytoplasmic processing bodies (P-bodies), which contain exonucleases, decapping enzymes, and microRNAs. mRNAs may be stored in P-bodies for future translation.
what initiates protein synthesis?
removal of N- or C-terminal propeptides from zymogen to generate mature protein (eg trypsinogen --> trypsin).
labile cell types
bone marrow + gut epithelium + skin + hair follicles + germ cells
stable cell types
hepatocytes + lymphocytes
1) protein distribution
2) modifies N-oligosaccharides on asparagine
3) adds O-oligosaccharides on serine and threonine.
4) adds mannose-6-phosphate
Signal recognition particle (SRP)
abundant, cytosolic ribonucleoprotein that traffics proteins from the ribosome to the RER. Absent or dysfunctional SRP leads to protein accumulation in the cytosol.
examples of intermediate filaments
vimentin + desmin + cytokeratin + lamins + glial fibrillary acid proteins (GFAP) + neurofilaments
stains for mesenchymal tissue (eg., fibroblasts, endothelial cells, macrophages).
9+2 arrangement of microtubule doublets. Base (basal body) consists of 9 microtubule triplets with no central microtubules.
ATPase that links peripheral 9 doublets and causes bending of cilium by differential sliding of doublets.
frequency of an x-linked recessive disease in males
frequency of an x-linked recessive disease in females
what is wrong in prader willi vs. angelmans
2 rules for inheritance chart
1) look for recessive/dominance
2) who's passing it down (only moms --> mitochondrial inheritance)
gene mutated in myotonic dystrophy type 1
Delayed relaxation of skeletal muscles after voluntary contraction or electrical stimulation. Feature of myotonic dystrophy.
medical word for night blindness