ATP powered pumps transport ions and various small molecules across membranes always against their concentration gradients.

TLS Online TPP Program

#Id: 9942

#Unit 4. Cell Communication and Cell Signaling

Diphtheria

Natural infection with C. diphtheriae occurs only in humans and is spread by respiratory droplets. 

The organism colonizes the nasopharyngeal tract and causes little tissue damage, with only a mild inflammatory reaction. 

TLS Online TPP Program

#Id: 4866

#Unit 13. Methods in Biology

level of significance defines whether the null hypothesis is assumed to be accepted or rejected. It is expected to identify if the result is statistically significant for the null hypothesis to be false or rejected.

TLS Online TPP Program

#Id: 2450

#Unit 3. Fundamental Processes

The lac operator overlaps the promoter, and so the repressor bound to the operator physically prevents RNA polymerase from binding to the promoter and thus initiating RNA synthesis.

TLS Online TPP Program

#Id: 6398

#Unit 2. Cellular Organization

Repression-Trp aporepressor dimer binds high tryptophan, changes conformation with high affinity for trp operator

Tryptophan is a corepressor

TLS Online TPP Program

#Id: 7308

#Unit 12. Applied Biology

In uranium leaching, Acidophillus ferrooxidans oxidizes U4+ to U6+ with O2 as an electron acceptor. 

However, Uranium leaching depends more on the abiotic oxidation of U4+  by Fe3+ with A. ferrooxidans contributing to the process mainly through the reoxidation of Fe2+ to Fe+3, as in copper leaching.