Biochem Flashcards
What carbohydrate metabolism disorder has no symptoms but will have a positive reducing sugar urine test
essential fructosuria (fructokinase deficiency)
What does riboflavin become, making it useful energy pathways
FMN
FAD
What type of receptor is the Calcium sensing receptor that regulates PTH
Gq protein coupled
Northern blots detect target ____ in a sample
mRNA
can be used to assess the degree of gene transcription
pneumonic for what each blot (northern , western, southern) detects
SNoW DRoP
DNA, RNA, protein
In prolonged fasting, what 3 hormones upregulate gluconeogenesis
cortisol
epinephrine
glucagon
Lactate dehydrogenase is required in order for anaerobic glycolysis to occur. Why
it generates NAD+ which is needed in G3P –> 1,3 BPG
Inclusion cell (I-cell) disease is a defect in what process?
posttranslational modification in the Golgi
normally proteins designated for lysosomes are tagged with mannose-6-phosphate therefore lysosomal acid hydrolases with be inappropriately transported to the extracellular space
Gq activation –> ____ activation –> IP3 and DAG –> activation of _____
phospholipase C
protein kinase C
What is the difference between proteins translated on free ribosomes vs ribosomes attached to the RER
free/cytosolic ribosomes: synthesize proteins found in the cytosol, nucleosol, peroxisome matrix and nuclear encoded mitochondrial proteins
RER: synthesize most secretory proteins, integral membrane proteins of nucleus and cell membranes, and proteins within the ER, Golgi, and lysosomes
In pyruvate dehydrogenase deficiency, increase in what amino acids is helpful?
lysine
leucine
(also high fat diet)
Proteins tagged with mannose-6-phosphate are ultimately transported to the _____
lysosome
gait instability, scaly erythematous skin lesions in sun exposed areas, cerebellar ataxia, increased levels of urine neutral amino acids is due to what disease and what vitamin deficiency
Hartnup
niacin
Intracellular receptors that bin ___, ____, and _____ act directly as transcription factors and contain zinc-finger binding domains
steroids
thyroid hormone
fat soluble vitamins
What dietary restrictions will lead to improved symptoms of aldolase B deficiency
fructose and sucrose (turned into fructose)
Ethanol metabolism causes increased ___ which inhibits what pathway leading to hypoglycemia
NADH
gluconeogenesis
what would be the cause of fever, uticarial rash and arthralgia 1-2 weeks after receiving polyvalent Fab antivenom treatment for a snake bite
serum sickness: type III hypersensitivity reaction due to IgG binding antivenom (made from plasma of venom-inoculated animals) and creating immune complexes which can overwhelm complement and macrophage clearing
A purpuric rash, arthralgia, and signs of renal disease (hypertension, proteinuria) indicate what diagnosis
Henoch-schonlein purpura
what is pathophysiology of henoch schonlein purpura
type III hypersensitivity reaction: depositions of IgA complexes triggers complement activation and inflammation of small vessels
what are histological findings in a patient with henoch schonlein purpura
leukocytoclastic vasculitis: superficial blood vessels are damaged by perivascular neutrophilic inflammation, resulting in fibrin deposition in the vessel wall (fibrinoid necrosis) and red blood cell extravastation and perivascular nuclear debris from neutrophil breakdown
What medication reduces inflammation by binding to a cytosolic receptor, translocating into the nucleus, and inhibiting proinflammatory transcription factors such as NF-kappaB
glucocorticoids (budesonide)
MOA budesonide
glucocorticoid
Tuberculin skin testing triggers type IV delayed-hypersensitivity reaction which is mediated by antigen recognition by APC with costimulation by APC ____ interacting with T cell ____
APC: CD80/86
Tcell: CD28
At normal physiologic conditions, which are high and which are low intracellularly relative to their outer cellular concentrations: K, Na, Cl
high intercellular: K
Low intercellular: Na, Cl-
Supplementation of ____ can reduce symptoms in uridine 5’-monophosphate synthesis (UMP) synthase deficiency
uridine
What is defective that causes Ehlers Danlos
collagen synthesis
Malignant epithelial cells in melanoma show decreased integrin expression which likely means they have decreased adherence to what component of the ECM
fibronectin
Essential fructosuria is benign due to the compensatory actions of what enzyme
hexokinase
converts fructose to F-6-P which can be converted to glucose or pyruvate
What is the most abundant amino acid in collagen?
glycine
What are the 2 major sources of glucose during prolonged fasting? what predominates the first 12-28 hours and what predominates after that?
first 12-18 hours: glycogenolysis
then gluconeogensis
How does NF kappa B become activated in the presence of bacteria
bacterial antigen binds toll like receptor ==> activation of IkB kindase —> ubiquitination and destruction of IkappaB –> NF kappa B is free and enters nucleus to promote synthesis of inflammatory proteins
Describe “anaplastic” tumors
undifferentiated, bear no resemblance to the tissue of origin
composed of pleomorphic cells with large, hyperchromatic nuclei that grow in a disorganized fashion. They may contain numerous, abnormal mitoses and giant tumor cells
Which of the following are tumor suppressor genes and which are proto-oncogenes: APC BRCA1 KRAS RB TP53
all are tumor suppressors except KRAS
Osteosarcomas typically arise from mesenchymal stem cells that develop mutations in what genes
RB1 and TP53
Ras is active when bound to what? What does Ras activate?
GTP
RAF (which causes a kinase cascade resulting in MAP kinase activity)
What movement of what ions contributes the resting potential of membranes
high potassium efflux and some sodium influx
