E. coli has at least four individual topoisomerases (I through IV). Those of type I (topoisomerases I and III) generally, relax DNA by removing negative supercoils (increasing Lk).

TLS Online TPP Program

#Id: 896

#Unit 13. Methods in Biology

Two REs recognize the same DNA sequence motif but cleave at different positions, then they are called neoschizomers

TLS Online TPP Program

#Id: 7214

#Unit 5. Developmental Biology

Class II presentation can occur with either live or replication-incompetent virus; protein synthesis inhibitors had no effect, indicating that new protein synthesis is not a necessary condition of class II presentation.

TLS Online TPP Program

#Id: 6509

#Unit 7. System Physiology – Animal

Phenylketonuria (PKU) 

Mutation of the gene for phenylalanine hydroxylase

Caused by tetrahydrobiopterin (BH4) deficiency

TLS Online TPP Program

#Id: 9929

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 6465

#Unit 3. Fundamental Processes

Proteins bound at enhancer elements interact with proteins bound at promoter elements via DNA looping, very often through intermediates called coactivators.