Regulation Of Eukaryotic Gene Expression

Question 1

4 month age baby with developmental abnormalities, impaired vision, hepatomegaly, high blood levels of Cu and Fe, failure in grow, mental retardation, hypotonic; besides evidence of very long fatty acids, hydroxylated and branched. Most probably disease and cause.

Answer 1

Zellweger syndrome.
*locus heterogeneity mutation - deficiency of peroxisomes ▶️ defect in fatty acid efflux ▶️ accumulation very long and rare fatty acids.

Question 2

Mechanism of action of fibrates and thiazolidinediones

Answer 2

Activate PPARs (Peroxisome proliferator-activated receptor)

• gamma - thiazo ▶️ improvement in insulin resistance
• Alfa - fibrates ▶️ bind to PPREs ▶️ ⬆️ proliferation Peroxisome and expression LPL ▶️ fatty acid oxidation

Question 3

Cause of developmental errors in various tissues in Klein-Waardenburg syndrome

Answer 3

Mutation in PAX-3 gene ➡️ homeodomain protein (HOX or PAX genes) ▶️ control embryonic gene expression. Expressed in different embryonic tissue.

Question 4

Exception of codominant expression

Answer 4

• Barr body in women
• Ig heavy and light chain
• T cell receptor loci

Question 5

Why tumor cells amplify gene expression of Dihydrofolate reductase?

Answer 5

Increase resistance to Metothrexate

Question 6

What control of gene expression mediate Prader-Willi and Angelman syndromes?

Answer 6

Methylation of DNA that silences genes in genetic imprinting