What Is the Difference Between the Trithorax (TrxG) and Polycomb

question 17

Multiple Choice

What is the difference between the trithorax (TrxG) and polycomb (PcG) complexes of proteins?

• A) TrxG proteins methylate lysine 27 on histone H3 while PcG complexes methylate lysine 4 on H3
• B) Methylation of lysine at position 4 on H3 results in silencing of gene expression
• C) TrxG complex proteins activate gene expression by methylating lysine 4 on H3, while PcG complex proteins repress gene expression by methylating lysine 27 on H3.
• D) Methylation of H3 on lysine 27 can result in activation of transcription

---

Definitions:

Pupil Dilation

The expansion of the pupil of the eye, often in response to low light conditions or as an expression of emotion.

Withdrawal Reflex

A spinal reflex that causes immediate withdrawal from a painful or harmful stimulus.

Interneurons

Neurons that transmit impulses between other neurons, especially as part of reflex arcs in the nervous system.

Endorphins

Natural pain-relieving peptides produced by the brain that also enhance feelings of pleasure.