March 24 - Biochemistry Flashcards
Gaucher disease: defect and presentation
Defect: beta glucocerebrosidase is deficient, glucocerebroside accumulates
Presentation: HSM, pancytopenia, bone pain
Mechanism of triple helix of collagen
Due to glycine occupying every third position in each alpha chain. Means that glycine is the most abundant amino acid in collagen
Pyruvate carboxylase
Uses biotin as cofactor for convert pyruvate to oxaloacetate in gluconeogenesis
Biotin deficiency
Increased pyruvate gets converted to lactic acid, leading to metabolic acidosis.
Also get accumulation of propionyl coA because can’t convert it to succinyl coA with propionyl coA carboxylase
Lac operon
Encodes three different genes involved in lactose metabolism. One mRNA transcript generates three different proteins
Conversion of norepinephrine to epinephrine
Occurs in adrenal medulla by enzyme PNMT, which is upregulated by cortisol
Maturity-onset diabetes of young pathophys and presentation
Pathophys: Heterozygous glucokinase deficiency. Results in decreased beta cell glucose metabolism and thus less insulin secretion.
Presentation: Mild, nonprogressive hyperglycemia that often worsens with pregnancy
Porphyria cutanea tarda
Photosensitivity due to accumulation of porphorinogens. Uroporphrinogen decarboxylase is deficiency
Acute intermittent porphyria enzymatic defet
Porphobilinogen deaminase
Elastin production
Synthesized as tropoelastin. Tropoelastin secreted to ECM where it interacts with fibrillin scaffold. Lysyl oxidase deaminates lysine residues, allowing desmosine crosslinks to form and giving elastin its rubber-like properties
Thiamine and B6 role in amino acid metabolism
Thiamine cofactor for dehydrogenase enzymes: branched chain alpha-ketoacid dehydrogenase and alpha ketoglutarate dehydrogenase
B6 a cofactor for transamination and decarboxylation steps of amino acid metabolism, as well as has a role in heme and neurotransmitter synthesis
Homocysteine metabolism
Homocysteine can be converted to methionine in process that requires B12 as cofactor
Can also be converted to cysteine in two steps, both of which require B6 as cofactor
Hereditary orotic aciduria
AR disorder of de novo pyrimidine snthesis. Defect is in UMP synthase.
Presents with physical and mental retardation, megaloblastic anemia, and elevated urine orotic acid.
Uridine supplementation bypasses the enzyme defect and improves symptoms
Hematoma progression
Following injury, hemoglobin containing RBCs escape resulting in purple/blue color of bruise. RBCs subsequently destroyed and heme released.
Heme oxygenase degrades heme to biliverdin and iron. Biliverdin gives green color to bruise.
Biliverdin then reduced to bilirubin which gives yellow color to bruise
Galactosyl beta 1,4 glucose
Another name for lactose
Succinate dehydrogenase
Enzyme in both TCA cycle and in ETC (complex II)
Converts succinate + FAD to fumarate + FADH2
Gq signling
Hormone binds receptor, activating G protein (Alpha subunit goes from GDP bound to GTP bound)
Alpha subunit activates PLC
PLC breaks down PIP2 to IP3 and DAG
DAG stimulates PKC which phosphorylates downstream targets
IP3 increases intracellular Ca++ which also stimulates PKC
Ketogenic amino acids
Leucine and isoleucine
Amino acids that are both ketogenic and glucogenic
Phenylalanine, isoleucine, tryptophan
Lead toxicity
Inhibits ALA dehydratase as well as ferrocheletase in heme synth
Bloom syndrome
DNA helicase mutation, results in chromosomal instability
Helicase vs topoisomerase vs ssBPs
Helicase: unwinds DNA
ssBPs: stablize unwound DNA
Topoisomerase: relieves coiling tension by creating temporary breaks in DNA. Found upstream of helicase
Fetal alcohol syndrome
Smooth philtrum, microcephaly, delayed growth, ADD
Hartnups disease
Defect in transport of neutral amino acids in renal and GI tracts resulting in wasting of neutral amino acids in the urine. Can result in pellagra due to wasting of tryptophan, which is used to make niacin. Also failure to thrive, photosensitivity, nystagmus, intermittent ataxia
