Molecular (Kaplan) 4

Question 1

Pt has depigmented (steely) hair, tortuous arterioles that tend to rupture, cerebral degeneration, osteoporosis, and anemia. What is the defect?

Answer 1

Menkes Disease: Functional copper deficiency (does not exit intestinal epithelium to circulation); inability to cros-link tropocollagen.

Question 2

What is the mode of inheritance of Menkes disease?

Answer 2

X-linked recessive

Question 3

Describe the dispositions of the activator and the repressor at the lac operon in the presence of glucose alone.

Answer 3

CAP-cAMP not bound

Repressor bound

Question 4

Describe the dispositions of the activator and the repressor at the lac operon in the presence of lactose alone.

Answer 4

CAP-cAMP bound

Repressor not bound

Question 5

Describe the dispositions of the activator and the repressor at the lac operon in the presence of both glucose and lactose.

Answer 5

CAP-cAMP not bound

Repressor not bound

Question 6

What modification of histones activates gene expression?

Answer 6

Acetylation

Question 7

What is the difference between upstream promoter elements (UPEs) and enhancers?

Answer 7

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).

Question 8

Briefly describe attenuation of transcription in the His operon.

Answer 8

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.

Question 9

What is the mechanism of action shared by fibrates (e.g. Gemfibrozil) and glitazones (thiazilidinediones)?

Answer 9

activate PPARs

Question 10

What are PPARs and what kind processes are they involved in?

Answer 10

transcription modulators: lipid metabolism

Question 11

What are the endogenous activators of PPARs?

Answer 11

FAs and PG derivatives.

Question 12

Which PPAR do fibrates work on? Glitazones?

Answer 12

fibrates - alpha

glitazones - gamma

Question 13

What is the main indication and mechanism of action of Gemfibrozil?

Answer 13

hypertriglyceridemia; stimulates peroxisome proliferation and upregulates lipoprotein lipase –> FA oxidation

Question 14

How do both cortisol and glucagon increase gluconeogenesis?

Answer 14

Increase production of PEPCK (RLS).

Question 15

Where is the receptor for cortisol (glucocorticoid receptor) located?

Answer 15

cytoplasm

Question 16

What is the cascade of events in glucagon’s upregulation of PEPCk synthesis?

Answer 16

bind to Gs receptor; increase cAMP; Protein kinase A activates CREB; CREB binds to CRE on DNA

Question 17

What are HOX and PAX genes?

Answer 17

encode transcritption factors for coordination of gene expression in utero.

Question 18

What syndrome results from PAX gene mutations?

Answer 18

Waardenburg syndrome

Question 19

What are the major Dx criteria of Waardenburg syndrome?

Answer 19

sensorineural deafness
depigmented forelock
differently or poorly pigmented or brilliant   blue eyes
wide-set eyes (dystopia canthorum)
1st degree relative w/ disease

Question 20

What is the inheritance pattern of Waardenburg syndrome?

Answer 20

Autosomal dominant

Question 21

Name 3 major exceptions to co-expression of heterozygous genes in humans.

Answer 21

1. Barr body
2. immunoglogulin heavy and lt chains in each B-cell
3. TCRs
   (also in genetic imprinting)

Question 22

Where does the repressor bind in the Lac operon?

Answer 22

the operator

Question 23

Where are enhancer sequences and what do they do?

Answer 23

They may be far from the gene, usu. on same chromosome. Bind activator proteins that stimulate RNA pol.

Question 24

What test is used for viral load in HIV pts?

Answer 24

RT-PCR

Question 25

What is the usual test combo for HIV? Which test is more sensitive?

Answer 25

ELISA/Western blot. ELISA is more sensitive.

Question 26

In what situations would you use PCR to test for HIV?

Answer 26

Early detection after needle stick and newborn of HIV+ mama. [ELISA/Western blot will always be (+).]