Gene Regulation and Repair

Question 0

Hypoxia Inducible Factor

Answer 0

Normal oxygen state - HIF1alpha is degraded in cytoplasm

In hypoxia, PHD does not mark HIF for degradation. HIF enters nucleus where it combines with its beta form and binds to genes carrying hypoxia-response elements.

Question 1

Lac Operon

Answer 1

Active in the presence of Lactose - Allolactose binds and removes repressor.

In the absence of glucose, cAMP binds CAP and together enhance pol II

Question 2

Myc/Max System

Answer 2

In the absence of Myc, the Max forms a homodimer and it represses gene transcription

In the presence of Myc, a Myc/Max heterodimer is formed to activate gene expression

Question 3

Iron Homeostasis

Answer 3

Ferritin is a iron storage protein in the cell
-Decreased Iron, Ferritin mRNA is blocked
-Increased Iron, Ferritin mRNA is translated
Blockage of promotor region ‘hairpin’ structures

Transferrin is a iron transport protein
-Decreased Iron, Transferrin mRNA is stabilized (protein allows for increased intake of iron from circulation)
-Increased Iron, Transferrin mRNA is degraded
Stabilization of the 3’ end of mRNA

Question 4

Types of spontaneous lesions

Answer 4

Depurination - breakage of bind between base and suger

Deamination - loss of amine group, ex) Cytosine to Uracil or 5’methyl Cytosine to Thymadine,

Oxidative Damage - results in oxygen additions to bases causing mismatches with Adenosine