Molecular (Kaplan) 4 Flashcards
Pt has depigmented (steely) hair, tortuous arterioles that tend to rupture, cerebral degeneration, osteoporosis, and anemia. What is the defect?
Menkes Disease: Functional copper deficiency (does not exit intestinal epithelium to circulation); inability to cros-link tropocollagen.
What is the mode of inheritance of Menkes disease?
X-linked recessive
Describe the dispositions of the activator and the repressor at the lac operon in the presence of glucose alone.
CAP-cAMP not bound
Repressor bound
Describe the dispositions of the activator and the repressor at the lac operon in the presence of lactose alone.
CAP-cAMP bound
Repressor not bound
Describe the dispositions of the activator and the repressor at the lac operon in the presence of both glucose and lactose.
CAP-cAMP not bound
Repressor not bound
What modification of histones activates gene expression?
Acetylation
What is the difference between upstream promoter elements (UPEs) and enhancers?
UPEs are close to the -25 promoter region (TATA box) and enhancers are located in other places in or near the gene (e.g. introns).
Briefly describe attenuation of transcription in the His operon.
As the first portion of the mRNA is produced, the ribosome binds. If His is readily available, a leader peptide is produced that folds into a terminator of transcription.
What is the mechanism of action shared by fibrates (e.g. Gemfibrozil) and glitazones (thiazilidinediones)?
activate PPARs
What are PPARs and what kind processes are they involved in?
transcription modulators: lipid metabolism
What are the endogenous activators of PPARs?
FAs and PG derivatives.
Which PPAR do fibrates work on? Glitazones?
fibrates - alpha
glitazones - gamma
What is the main indication and mechanism of action of Gemfibrozil?
hypertriglyceridemia; stimulates peroxisome proliferation and upregulates lipoprotein lipase –> FA oxidation
How do both cortisol and glucagon increase gluconeogenesis?
Increase production of PEPCK (RLS).
Where is the receptor for cortisol (glucocorticoid receptor) located?
cytoplasm
What is the cascade of events in glucagon’s upregulation of PEPCk synthesis?
bind to Gs receptor; increase cAMP; Protein kinase A activates CREB; CREB binds to CRE on DNA
What are HOX and PAX genes?
encode transcritption factors for coordination of gene expression in utero.
What syndrome results from PAX gene mutations?
Waardenburg syndrome
What are the major Dx criteria of Waardenburg syndrome?
sensorineural deafness depigmented forelock differently or poorly pigmented or brilliant blue eyes wide-set eyes (dystopia canthorum) 1st degree relative w/ disease
What is the inheritance pattern of Waardenburg syndrome?
Autosomal dominant
Name 3 major exceptions to co-expression of heterozygous genes in humans.
- Barr body
- immunoglogulin heavy and lt chains in each B-cell
- TCRs
(also in genetic imprinting)
Where does the repressor bind in the Lac operon?
the operator
Where are enhancer sequences and what do they do?
They may be far from the gene, usu. on same chromosome. Bind activator proteins that stimulate RNA pol.
What test is used for viral load in HIV pts?
RT-PCR
What is the usual test combo for HIV? Which test is more sensitive?
ELISA/Western blot. ELISA is more sensitive.
In what situations would you use PCR to test for HIV?
Early detection after needle stick and newborn of HIV+ mama. [ELISA/Western blot will always be (+).]
