The video explains why cells do not use D-amino acids in protein synthesis. Proteins are made using L-amino acids due to their compatibility with the protein translation machinery. The DTD enzyme plays a crucial role in preventing D-amino acids from being incorporated into proteins, ensuring proper cell function. This mechanism has been vital throughout evolution, allowing proteins with L-amino acids to develop across all life forms.

What is the primary function of proteins in living cells?

• To act as the workhorses of the cell

• To transport oxygen

• To provide structural support

• To store genetic information

Why are only L-amino acids used in protein synthesis?

• They are more stable

• They are more abundant in nature

• They bind more easily to protein translation machinery

• They are less reactive

What is the role of tRNA in protein synthesis?

• To synthesize RNA

• To degrade proteins

• To replicate DNA

• To transport amino acids to the ribosome

What potential problem can occur if D-amino acids are incorporated into proteins?

• The cell's function may be disrupted or it may die

• The protein may become more reactive

• The protein may become more stable

• The protein may become more flexible

What is the function of the enzyme D-aminoacyl tRNA deacylase (DTD)?

• To bind to L-amino acids

• To degrade proteins

• To synthesize D-amino acids

• To remove D-amino acids from tRNA

How does DTD prevent D-amino acids from being used in protein synthesis?

• By binding to them and preventing their incorporation

• By storing them in vesicles

• By converting them to L-amino acids

• By degrading them

What is unique about the pocket in DTD?

• It fits both L and D-amino acids

• It fits D-amino acids linked to tRNA

• It fits L-amino acids linked to tRNA

• It fits only free amino acids

What does the presence of DTD across all life forms suggest?

• It is only found in multicellular organisms

• It has been important throughout evolution

• It is not essential for life

• It is a recent evolutionary development

What role has DTD played since early unicellular life?

• It has synthesized proteins

• It has degraded L-amino acids

• It has acted as a chirality filter

• It has helped incorporate D-amino acids