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Flashcards in Clinical cases/drugs Deck (21):
1

People with maple syrup urine disease have high urine levels of keto-acids and high serum levels of branched chain amino acids. How would you address this and why?

In the disease, branched chain amino acids can't be degraded properly, so diet must be monitored very carefully

2

In class III and IV cystic fibrosis, on the affected receptor, gly is replaced with asp and arg is replaced with his, respectively. How would these changes affect the receptor ?

Class III: Makes it more negatively charged
Class IV: Doesn't change the charge, but bulky his R-group could affect structure

3

Quinolone is a type of antibiotic that specifically targets topoisomerase II, inhibiting its ligase activity. How would this affect DNA structure?

It would prevent its ability to rejoin DNA strands after unwinding them, resulting in bits of cleaved DNA

4

HIV is often treated with NRTI's. NRTI's are nucleoside analogs. How do these drugs work?

They are incorporated into the DNA chain upon replication, but do not allow replication to proceed because of their lack of 3' hydroxyl groups

5

Myotonic dystrophy is a disease that is caused by trinucleotide repeats caused by a "slippage" of DNA polymerase during replication. What is the phenomenon associated with its inheritance called?

Anticipation. Each successive replication causes additional "slips," meaning progeny start out with more repeats and therefore have more severe symptoms

6

Aicardi-Goutieres disease results from a mutation in genes including one that code for RnaseH. Why is this significant?

RnaseH is responsible for removal of primers during DNA replication. This would cause structural abnormalities in the DNA

7

Turner syndrome is a x- chromosome monosomy disease. If normal people with two x normally have one inactivated anyway, why does Turner syndrome arise?

Some genes on the x escape inactivation and remain active. Total loss of one of the two chromosomes results in a gene dosage issue

8

CMMRD is a disease that results from mutations in genes that code for, among others, MutS, L, and H. What process are these proteins important for?

Mismatch base repair

9

Xeroderma pigmentosum is a rare disease that affects what type of DNA repair?

Nucleotide excision repair as a result of thymidine dimers

10

What is the mechanism of action of rifampicin?

It inhibits the formation of the first phosphodiester bond in transcription by binding to the prokaryotic RNA polymerase beta subunit

11

What is the mechanism of alpha-amintin?

It inhibits eukaryotic RNA polymerase II

12

B-thalassemia major is a disease in which a single point mutation in the thalassemia gene creates a splice site. How would this affect the disease form protein?

Results in a short non functional protein

13

What is the process that affects abnormalities in CD44 that are associated with increased cancer risk?

Alternative splicing, causes certain gene variants to be inappropriately expressed

14

In diseases involving mutations of the basic region of transcription factors, why would these mutations be a problem?

Affects the TF's ability to bind DNA

15

Rett syndrome results from a mutation in the MeCP2 gene. What process would this affect?

Regulation of gene expression via methylation

16

Prader-willi is a disease resulting from ___ deletion of a ___ imprinted gene

paternal, maternal

17

Angelman's is a disease resulting from ___ deletion of a ___ imprinted gene

maternal, paternal

18

How can uniparental disomy also cause Prader-willi or Angelman's

UD happens when two chromosomes are inherited from a single parent and not the other. This would effectively lead to the same result as a deletion, since both copies of the same gene would be imprinted.

19

What is unique about HCV and how its DNA is translated?

It doesn't require a 5' cap to be recognized and instead contains IRES which is recognized by the 40s/eIF3 complex

20

On Philadelphia chromosomes + CML cells, the Bcr-ABL protein is overactive. What pathway is this pertinent to?

RTK pathway

21

p53 is pleiotropic, meaning what? Why is this important?

It influences many seemingly unrelated functions. Mutations in p53 are therefore a large part in many cancer types