The Genes we Lost Along the Way (V1)

Exam 2 Video 1

What is GULOP, where is it found in the human genome, and what function did it used to perform in early primates?

GULOP is a gene on chromosome 8 that allows primates to produce their own vitamin C.

What are pseudogenes, and why does the video describe them as “molecular fossils”?

Pseudogenes are ‘dead’ non-functional genes.

“Molecular fossil” refers to how it is a remnant in our DNA and a link to our past ancestry.

What is UoX, what enzyme did it code for, and what human health condition is linked to its loss?

A gene on chromosome 1 that coded for the protein Uricase, which breaks down uric acid, a waste product of metabolism.

This leads to gout/ buildup of uric acid, but led to fat storage for winter

There are pseudogenes formed by gene duplication vs. “unitary” pseudogenes. What’s the difference, and which category do GULOP and UoX fall into?

• Pseudogenes formed via gene duplication are genes that became non-functional after making a copy of themselves

• “unitary” pseudogenes are genes that just don’t function anymore - GULOP + UoX

How can a gene-inactivating mutation spread through a population rather than being eliminated?

The loss of the gene doesn’t reduce the fitness of the species. Eventually, it can become “fixed”, meaning it’s the only version of that gene left in the species/ the original gene is gone.

What is ancestral sequence reconstruction, and how did researchers use it to study the decline of uricase function leading up to UoX becoming a pseudogene?

ASR compares genes and proteins of uricase in modern mammals to reverse engineer what those genes/proteins would’ve looked like at different points in the past, and then resurrects the gene.

By the time we lost the gene, it was already incredibly inefficient.

How does the bitter taste receptor connect gene loss to changes in diet and culture? what the shared pseudogenes in humans, Neanderthals, and Denisovans imply about timing and ancestry.

We have 25 working bitter taste receptors and 11 dead ones.

These pseudogenes died before we split from our fellows

They died because we didn’t need to taste plants to know they are toxic, because we could communicate with each other, and because our knowledge of food was expanded.