First aid Biochemistry Flashcards
What type of DNA is in the nucleus and what charge does it carry?
It is densely negatively charged chromatin.
Bound around positively charged histones rich in lysine and argine.
Describe the difference between histone methylation and histone acetylation.
Methylation generally makes DNA mute.
Acetylation relaxes DNA for transcription.
Nucleotide vs nucleoside
Nucleotide is the base, deoxyribose, and a phosphate.
Nucleoside is just the base, deoxyribose and sugar.
Adenosine deaminase deficiency can lead to what disease order?
Excessive ATP and dATP imbalances nucleotide pool preventing DNA synthesis and lowering lymphocyte count.
This is a common cause of SCID.
What is Lesch-Nyhan Syndrome?
Defctive purine salvage due to abscent HGPRT which converts hypoxanthine to IMP and guanine to GMP.
Results in excess uric acid production and denovo purine synthesis!!
Intelectual diability, self mutilation, agression, hyperuricemia, and gout.
Describe the formation of uric acid
Ribose 5 phosphate creates IMP which is then broken down to inosine an finally hypocanthine.
Xanthine oxidase is then responsible for breaking hypoxanthine down into xanthine and finally uric acid that is meant to be secreted.
Any problems in this area can lead to hyperuricemia and gout.
Single stranded biding proteins
Keep DNA from recombining after being opened for transcription.
DNA topoisomerases
These create single and double stranded breaks to help unwind the DNA supercoils. Fluoroquinolones inhibit this enzyme leading to DNA damage. (specifically topoisomerase II)
Primase
Makes RNA primer for DNA polymerase to begin replication on.
What is a silent mutation?
Nucleotide substition but codes for same amino acid.
Missense mutation
Nucleotide substitiution resulting in changed amino acid
In sickle cell disease a glutamic acid is subtituted with a valine.
What substitution occurs in sickle cell disease?
Glutamic acid is substituted with a valine.
Nonsense mutation?
Nucleotide substitution that inserts a stop codon.
“Stop the nonsence”
Duchenne muscular dystrophy is a result of….
A frameshift through deletion or subtitution of a nucleotide.
Xeroderma pigmentosum
Sun damage leading to pyrimidine dimers because of ultralight exposure.
Generally protected by nucleotide excision repaire.
what direction are DNA and RNA synthesized?
5’ to 3’
Protein synthesis however is N terminus to C terminus.
What does the start codon AUG code for in eukaryotes and prokaryotes?
Eukaryotes codes for methionine
Prokaryotes codes for fMET
mRNA stop codons
UGA You go away
UAA You are away
UAG You are gone
RNA pol1
RNA pol2
RNA pol3
rRNA
mRNA
tRNA
What are the eukaryotic and prokaryotic ribosomal subunits?
Eukaryotes: 40S and 60S form 80S
Prokaryotes: 30S and 50S form 70S
What does tRNA bind to first?
Binds to the A site first.
Will then transition from the A site to the P site and finally the E site.
Elongation occurs at the P site.
What does chaperone protein do?
It is responsible for maintaining protein folding while under stress from heat atc.
Hsp60 is specifically produced in response to heat.