Class I enzymes attach the amino acid to the 2’-OH of the tRNA and are generally monomeric. Class II enzymes attach the amino acid to the 3’-OH of the tRNA and are typically dimeric or tetrameric.The amino acids for which the Class I synthetases are specific tend to be larger and more hydrophobic than those for Class II synthetases.

TLS Online TPP Program

#Id: 1891

#Unit 4. Cell Communication and Cell Signaling

T-cell education

TLS Online TPP Program

#Id: 9881

#Unit 4. Cell Communication and Cell Signaling

Defensins and cathelicidin LL-37 are secreted constitutively by epithelial cells in many tissues, and are stored as well in neutrophil granules, where they contribute to killing phagocytosed microbes.

TLS Online TPP Program

#Id: 953

#Unit 5. Developmental Biology

In Strongylocentrotus purpuratus, the acrosome reaction is initiated by a repeating polymer of fucose sulfate.

TLS Online TPP Program

#Id: 5373

#Unit 10. Ecological Principles

The mark-recapture technique is that after the tagged animals are released, they mix freely with unmarked individuals. The population is resampled and the numbers of marked and unmarked individuals are recorded. 

TLS Online TPP Program

#Id: 3117

#Unit 3. Fundamental Processes

The origin of E. coli, oriC, is 245 bp in length. The genome of E. coli is replicated bidirectionally from a single unique site called the origin, identified as the genetic locus oriC.

Two replication forks initiate atoriCand move around the genome at approximately the same speed to a special termination region.