In Escherichia coli, MutS scans the DNA, recognizing mismatches from the distortion they cause in the DNA backbone. 

MutS has an ATPase activity that is required for mismatch repair and recruits MutL, a second protein component of the repair system. MutL, in turn, activates MutH, an enzyme that causes an incision or nick on one strand near the site of the mismatch. Nicking is followed by the action of a specific helicase (UvrD) helicase unwinds the DNA, starting from the incision and moving in the direction of the site of the mismatch, and the filled in by DNA polymerase III

TLS Online TPP Program

#Id: 9740

#Unit 6. System Physiology – Plant

Cyanogenic glycosides represent a particularly toxic class of N-containing secondary metabolites. 

Upon tissue damage, these glycosides break down and release hydrogen cyanide (HCN). 

TLS Online TPP Program

#Id: 9741

#Unit 6. System Physiology – Plant

Cyanide inhibits cytochrome c oxidase in the mitochondria, which blocks the electron transport chain.

TLS Online TPP Program

#Id: 9742

#Unit 6. System Physiology – Plant

Amygdalin (the common cyanogenic glycoside found in the seeds of almonds, apricots, cherries, and peaches). 

Dhurrin from sorghum 

Linamarin and lotaustralin from cassava.

TLS Online TPP Program

#Id: 9743

#Unit 6. System Physiology – Plant

Glycosylated triterpenoid compound avenacin A1, found in oat (Avena sativa) roots The wheat root pathogen Gaeumannomyces graminis var. tritici is extremely sensitive to avenacins

TLS Online TPP Program

#Id: 9744

#Unit 6. System Physiology – Plant

Tomato plants produce tomatine, a compound that is closely related to avenacin. Only certain pathovars of the fungal pathogen Septoria lycopersici can cause disease on tomatoes, and these pathovars produce a glucosidase that can detoxify tomatine.

TLS Online TPP Program

#Id: 9745

#Unit 6. System Physiology – Plant

According to Optimal Defense Hypothesis, 

Young tissues not only contain the highest levels of constitutive secondary compounds, they are also more responsive to herbivory. Thus, younger leaves exhibit more robust inducible defenses to herbivores than older leaves.