First Aid: Biochemistry Flashcards
DNA and histone methylation make DNA _____________.
sterically inaccessible
Histone acetylation ________ DNA.
activates
Nucleosides have ________.
only sugars (think of the S)
Nucleotides have _________.
phosphates (think of the T)
Methotrexate inhibits ___________.
dihydrofolate reductase, which is necessary for thymine synthesis
Ataxia telangiectasia is a defect of the ___________ pathway.
non-homologous end joining
What do RNA polymerases I, II, and III do?
I makes rRNA, II makes mRNA, and III makes tRNA.
snRNPs control _______, while miRNA _______.
splicing; decreases translation by degrading mRNA
tRNA binds amino acids at the _____ end.
3’
tRNA use ______ to charge and _______ to translocate through the rRNA.
ATP; GTP
COP I is _______ movement, while COP II is _________; clathrin is ________.
retrograde; anterograde; a trafficker between the trans-Golgi and the membrane
What is Menkes disorder?
An X-linked, recessive defect of copper absorption that leads to kinky hair, growth retardation, and hypotonia–connective tissue issues.
Marfarns is an _________.
autosomal dominant defect of fibrillin, a glycoprotein that forms sheath around elastin; presents with long limbs and fingers, pectus excavatum, and heart problems
Polycystic kidney disease… AR or AD?
Both!
FAP…. AR or AD?
AD
Hereditary spherocystosis… AR or AD?
AD
p53 is shown by _________.
SBLA (sarcoma, breast, leukemia, and adrenal gland cancers)
MEN (multiple endocrine neoplasias) is associated with the __________ genes.
MEN1 (for type 1) and RET (for types 2A and 2B)
Cystic fibrosis is an __________.
autosomal recessive defect, most commonly of Ph508
What are the symptoms of myotonia type 1?
Myotonia (inability to relax muscles), testicular atrophy, frontal balding, and arrhythmia (my tonia, my testicles, my toupee, and my ticker)
Duchenne’s results from ________.
frameshift or nonsense mutations in the dystrophin gene
What are the trinucleotide repeat disorders?
Huntington, myotonic dystrophy, Friedrich ataxia, and fragile X (try hunting for my fried eggs [X])
Atresia is ________.
a disorder in which an orifice or passage that should be open is closed
95% of Down syndrome cases result from ___________.
meiotic nondisjunction (the rest are due to Robertsonian translocations)
Edwards syndrome is trisomy _____ and Patau syndrome is trisomy _____.
18 (think E = election age); 13 (think Patau = P = puberty age)
Histone _____ is on the outside of the nucleosome.
1
H1 is the linker.
___________-chromatin is darker on EM.
Hetero
“HeteroChromatin is Highly Condensed”
Which kind of chromatin gets expressed?
Euchromatin
“Euchromatin is Expressed”
Deamination of ______ makes uracil.
cytosine
Methylation of uracil makes _____________.
thymine (hence methotrexate inhibits the formation of thymine from uracil)
What enzyme initiates the pyrimidine synthesis pathway?
Carbamoyl phosphate synthase!
Recall that mitochondrial carbamoyl phosphate synthase makes carbamoyl phosphate for exportation into the urea cycle, while cytosolic CPS makes pyrimidines.
UMP is made from what precursor?
Orotic acid
Hence, this is why some pyrimidine synthesis disorders can present with elevated orotic acid.
HGPRT catalyzes what two reactions?
- Hypoxanthine to IMP
- Guanine to GMP
It’s in the name: hypoxanthine guanine phosphoribiosyltransferase
Say a patient with Lesch-Nyhan is allergic to allopurinol. What treatment can you give them?
Febuxostat
