Human Syndromes with Defects in DNA repair Flashcards
skin cancer, UV sensitivity, neurological abnormalities; nucleotide excision repair is affected
Xeoderma pingmentosum
leukemia, lymphoma, gamma ray sensitivity, genome instability; ATM protein, a protein kinase activated by double strand DNA breaks
Ataxia Telangiectasia
Breast and ovarian cancer; repair by homologous recombination is affected
BRCA1
UV sensitivity, developmental abonormalities; coupling of nucleotide excision repair to transcription.
accumulation of arrested transcription complexes at lesion sites; RNA pol is depleted
cockayne syndrome
RNA polymerase is part of the repair process by stalling at DNA alterations (NER) during transcription and calls forth coupling proteins which direct excision repair machinery to these sites.
Transcription coupled repair
involves removing a set of nucleotides, then ligating the strands back together; results in a deletion
nonhomologous end joining
occurs after replication when nearby daughter DNA strand duplex can serve as template for repair
homologous recombination
group of enzymes that form phosphodiester bonds between ribonucleotides
RNA polymerases
transcribes rRNA genes
RNA pol 1
transcribes all protein coding genes
RNA pol 2
transcribes tRNA genes
RNA pol 3
sequence of DNA nucleotides that signal the starting point for RNA synthesis
promter
binds to TATA box and has a subunit called TBP TATA BINDING PROTEIN
TFIID
blank determines when RNA pol will dissociate from the helix
Elongation factors
where is RNA pol 2 phosphorylated?
C terminal domain
snRNA + 7 protein subunits is
snRNP ribonucleotide protein
sequence of RNA transcript mutation into an mRNA
- 5’ end cap as it emerges from RNA polymerase
- spliceosomes assemble to delineate intron/exon boundaries
- when RNA pol reaches specific consensus sequences, special protiens are called forth that are eventually transferred to the 3’ end processing sequence.
these are most abundant in the nucleus and help package mRNA
hnRNPs heterogenous nuclear ribonucleoproteins
mRNA requires a (blank) similar to a key that opens the pore complex lock
nuclear transport receptor
site of rRNA processing and incorporation of rRNAs into ribosome subunits
not membrane bound
contains rRNA genes, precursor rRNAs, mature rRNAs processing enzymes, partly assembled ribosomes
nucleolus
converting the mRNA sequence into the language of amino acids is called
translation
synthesized by RNA pol 3 in the nucleus
tRNA
synthesized first as a precursor molecule with introns that must be removed
tRNA
tRNA requires this for recognition and attachment of the correct amino acid to the 3’ end
aminoacyl-tRNA synthetase
Protein is synthesized from….
N terminal end to C terminal end
this ribosomal subunit is important for matching tRNA to codon on mRNA
small subunit
this ribosomal subunit catalyzes the formation of peptide bonds between amino acids
large subunit
hold tRNAs tightly if the anticodon forms base pairs with complementary codon on the mRNA
A and P site
four major steps to chain elongation
tRNA biding
peptide bond formation
large subunit translocation
small subunit translocation
mRNA is translated in
the 5’ to 3’ direction starting with amine terminus
EFI and EF2 in eukaryotes speed up translation process
elongation factors
responsible for catalytic activity in forming covalent peptide bonds not proteins
rRNAs
initiates early protein folding; looks for stretches of hydrophobic amino acids which trigger ATP hydrolysis
HSP70
aid in correcting incorrectly or incompletely folded protein
HSP60
highly conserved eukaryotic protein with many functions
ubiquitin
endocytosis
multiubiquitylation
histone regulation
monoubiquitylation
proteasomal degradation; DNA repair
polyubiquitylation
surface amino acid sequences recognized by the enzymes
degrons
recognize the ubiquitin’s on a protein and begin digestion
proteasomes
