Biochem, Molecular Flashcards
What vitamin should be supplemented with neonatal phototherapy?
riboflavin (B2) bc the light degrades it
Name a genetic disorder that is assoc w abnormal splicing variants.
Beta-thalassemia
What are the effects of medium/long-chain acyl-CoA dehydrogenase deficiency? Tx?
Inability to beta-oxidize fatty acids = accumulation of carnitines + less ATP -hypoketotic hypoglycemia -hypotonia (frog leg) -seizures -hyperammonia Tx: avoid fasting
Which base pairs indicate splice acceptor site? Splice donor site?
acceptor: 3’ invariant AG
donor: 5’ GT/GU
What are the symptoms and treatment for Galastosemia?
Absent galatose-1-P UT = cataracts, fail thrive, jaundice
Tx: remove galactose + lactose/glucose from diet
What is primase?
Complex that synthesizes a short strand of RNA that’s needed before DNA can be synthesized
What is Beriberi in adults?
Profound thiamine def
- dry = peripheral neuropathy
- wet = cardiac involvement
What are the symptoms of UMP synthase def?
blockage of pyrimidine synthesis –> megaloblastic anemia w orotic crystals in urine
Which 2 enzymes does citrate allosterically affect?
negative regulator: phosphofructokinase I (PFK I) (glycolysis)
positive regulator: acetyl CoA carboxylase (fatty acid syn)
What are the risk factors for severe hyperbilirubemia in neonates?
- male
- premature
- jaundice within 24hrs
- maternal use of TMP-SMX (binds albumin which cant bind bili = kernicterus)
How does cortisol stimulate glucose production?
Cortisol induces gluconeogenic enzymes by increasing gene expression (not via cascades)
How does delta F508 mutation affect the CFTR gene?
Prevents proper folding = unstable and ubiquinated and digested
Lipoprotein lipase catalyzes what process?
Breakdown of triglycerides in chylomicrons into free fatty acids and glycerol def = accumulation of chylos --> milky plasma
What is Lesch-Nyhan Syndrome and its symps?
HGPRT def = excess purine synthesis (hyperuricemia) -spastic cerebral palsy -self-mutilation*(hand/lips) -gout/arthritis TX: allopurinol
lead poisoning inhibits which 2 enzymes?
- aminolevulinate dehydratase (ALA)
- ferrochelatase
= microcytic, hypochromic anemia
What is familial hypocalciuric hypercalcemia (FHH) and its symps?
mutation in Ca-sensing receptor gene (CaSR) = no feedback inhibition of PTH –> hyperCa, hypoCa in urine, Hyper/norm PTH
How does phenylalanine affect a fetus (mom w PKU)?
Phenylalanine crosses the placenta; if elevated can act as a teratogen to fetus
What is Acute Intermittent Porphyria and its symps?
Porphobilinogen deaminase def = inc urinary delta-ALA and PBG; 5 Ps: Painful abdomen Port wine–colored urine Polyneuropathy (tachy, HTN) Psychological disturbances Precipitated by drugs
What enzyme is mutated in Ehlers-Danlos Syndrome and what does it do?
Lysyl hydroxylase; hydroxylation of lysine residues for cross-linking collagen
What is Pompe disease (II)?
alpha-1,4-glucosidase def = skeletal and cardiac muscle symps (cardiomegaly, hepatomegaly, heart fail); NO hypoglycemia
What is the molecular mechanism for a trinucleotide repeat expansion mutation?
DNA replication error during S-phase; caused by slippage of polymerase during replication of repeat regions
What is the biochemical mechanism behind hemorrhagic disease of the newborn?
Vit K def –> defective gamma-carboxylation of glutamate residues
-antibiotics can interfere w Vit K production in breast milk
What is I-cell Disease?
defect in N-acetylglucosaminyl-1-phosphoTRANSFERASE
= golgi fails to phosphorylate mannose –> proteins secreted extracellularly not delivered to lysosomes
-coarse facial features
-immobile joints
-high plasma lyso enzymes
-cell inclusions
What is Glucose-6-phosphate Dehydrogenase def?
= less NADPH –> RBCs vulnerable to oxidative damage
- hemolytic anemia w Heinz bodies + Bite cells
- anemia precipitated by antimalarials, fava beans, sulfas
What are the hallmarks of Vit C def?
Scurvy: swollen gums, bruising/petechiae, perifollicular hemorrhages, corkscrew hair
How are cocaine and PFK-1 related?
Cocaine blocks norepi –> tachy + vasoconstrict
= cardiac ischemia and switch to anaerobic metabolism
–> Inc PFK-1 to switch from aerobic to anaerobic
What is Maple Syrup Urine Disease?
def of branched-chain ketoacid dehydrogenase = no breakdown Iso,Leu,Val
- lethargy, poor feeding, vomiting
- CNS: convulsions, coma
- Mennonites in PA
When an obese person diets, where does the majority of glucose come from?
glycerol from fat breakdown
What is the composition of gallstones from in ppl w hemolytic anemia (sickle cell)?
calcium bilirubinate
A diet containing milled rice is associated with what vitamin def?
Thiamine –> Beriberi (dry:polyneuritis, muscle waste) (wet: cardiomyopathy, edema)
Describe a fructose-1-phosphate aldolase (aldolase B) def.
= accumulation of fructose-1-phosphate which inhibits glycogenolysis and gluconeogenesis –> severe hypoglycemia when eating fruit
Describe a pyruvate carboxylase def.
PyrCarb converts Pyruvate –> oxaloacetate; enzyme def = build up of precursors alanine, pyruvate, lactate
- seizures
- hypotonia
- developmental delay
Where are chylomicrons produced?
enterocytes (intestinal epi cells) using dietary lipids
Where are chylomicrons metabolized?
vascular endothelium of adipose tissue via lipoprotein lipase
Describe Pyruvate kinase def.
= dec ATP = rigid RBCs (hemolytic anemia), inc 2,3-BPG
- hemolytic anemia of newborn
- mild for adults
- autosomal recessive (G6PD def is x-linked)
What are hallmarks associated with Hereditary Nonpolyposis colon cancer?
- microsatellite instability (dinucleotide)
- loss of function in mismatch repair genes MLH1/MSH2
What is Niemann-Pick Disease?
Sphingomyelinase def = neurodegen, hepatosplenomegaly, foam cells (fat macros)
Note: No hepato in Tay-Sachs
What is ataxia telangiectasia?
defect in ATM gene = no DNA ds break repair Triad: -ataxia (wheelchair) -angiomas (telangiestasias) -IgA def
NO activates which enzyme to cause vasodilation?
Guanylate cyclase
Von Gerke (I) is def in what enzyme?
glucose-6-phosphate
Pompe (II) is def in what enzyme?
alpha-1,4-glucosidase
aka
acid maltase
Cori (III) is def in what enzyme?
debranching enzyme
aka
alpha-1,6-glocosidase
McArdle (V) is def in what enzyme?
glycogen phosphorylase
aka
myophosphorylase
What are the essential amino acids?
PVT TIM HALL Phen Val Tryp Thre Iso Met His Arg Lys Leu
What is homocystinuria?
Cystathionine synthase def = marfanoid, kyphosis, lens dislocation, intellect disability
What does AATAAA code for?
Cleavage and polyadenylation
Cancer/tumor antigen to produce the highest antibody titer?
HPV 16 E6 (p53) bc its a mutant tumor suppressor, so body attacks w abs
What do tyrosine kinases do?
act as downstream effectors of various growth factors, they function through phosphorylating tyrosine residues on different proteins
What needs to be inhibited in methanol (paint thinner) poisoning?
alcohol dehydrogenase bc it forms formaldehyde
What does ribosome peptidyl transferase do?
Establish covalent bonds between amino acids
Impaired voltage-gated Na channels would cause what?
slowed conduction (of myelin sheath)
