Mitotic exit network plays an important role in shutting off mitotic cyclins by controlling the activation of the Cdc14 phosphatase through a GTPase pathway.

TLS Online TPP Program

#Id: 6113

#Unit 3. Fundamental Processes

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: 8396

#Unit 2. Cellular Organization

Each sarcomere contains two major types of filaments: 

Thick filaments (myosin II)

Thin filaments (actin and associated proteins)

TLS Online TPP Program

#Id: 10142

#Unit 6. System Physiology – Plant

PHYSIOLOGICAL EFFECTS OF AUXIN:

Three main guidance systems control the orientation of plant growth:

1. Phototropism, 

2. Gravitropism, 

3. Thigmotropism

TLS Online TPP Program

#Id: 5820

#Unit 7. System Physiology – Animal

Apparent mineralocorticoid excess (AME)

11β-hydroxysteroid dehydrogenase type 2 is inhibited or absent

TLS Online TPP Program

#Id: 3998

#Unit 2. Cellular Organization

One approach is to measure the effect of nicking the DNA. Unconstrained supercoils are released by nicking, whereas constrained supercoils are unaffected. Nicking releases -50% of the overall supercoiling.

Another approach uses the crosslinking reagent psoralen, which binds more readily to DNA when it is under torsional tension. The reaction of psoralen with E. coli DNA in vivo corresponds to an average density of 1 negative super helical turn/200 bp (sigma = -0.05).