Create an account to track your scores
and create your own practice tests:
Test: MCAT Biology
In 2013, scientists linked a cellular response called the unfolded protein response (UPR) to a series of neurodegenerative diseases, including such major health issues as Parkinson’s and Alzheimer’s Disease. According to their work, the unfolded protein response is a reduction in translation as a result of a series of enzymes that modify a translation initiation factor, eIF2, as below:
In the above sequence, the unfolded protein sensor binds to unfolded protein, such as the pathogenic amyloid-beta found in the brains of Alzheimer’s Disease patients. This sensor then phosphorylates PERK, or protein kinase RNA-like endoplasmic reticulum kinase. This leads to downstream effects on eIF2, inhibition of which represses translation. It is thought that symptoms of neurodegenerative disease may be a result of this reduced translation.
We do not know the exact action of eIF2 after it has been acted upon by PERK, and therefore cannot draw conclusions about the phosphorylation or dephosphorylation of transcription factors.
1. | Which of the following is most likely the molecular event that causes repression of translation, based on the information in the passage? |
Phosphorylation of eIF2
Phosphorylation of transcription factors
Dephosphorylation of transcription factors
Phosphorylation of the unfolded proteins
Dephosphorylation of eIF2
Certified Tutor