Both the pi helix and the 310 helix occur rarely and usually only at the ends of a helices or as single-tum helices. They are not energetically favorable, since the backbone atoms are too tightly packed in the 310 helix and so loosely packed in the n helix that there is a hole through the middle. 

Only in the a helix are the backbone atoms properly packed to provide a stable structure.

TLS Online TPP Program

#Id: 7600

#Unit 5. Developmental Biology

The mammalian egg encounters a heterogeneous population of sperm. Some sperm have undergone the acrosome reaction in or near the cumulus, whereas others have not. The egg have pathways for accepting both types of capacitated sperm.

TLS Online TPP Program

#Id: 6546

#Unit 7. System Physiology – Animal

Insulin also activates PKB which phosphorylates the Rab GAP protein AS160

TLS Online TPP Program

#Id: 2617

#Unit 13. Methods in Biology

Type I restriction endonucleases cleave the DNA about 1000 bp away from the 5'-end of the sequence "TCA" located within the recognition site.

TLS Online TPP Program

#Id: 3361

#Unit 3. Fundamental Processes

Photoreactivation; Ultraviolet irradiation causes formation of thymine dimers. Upon exposure to light, DNA photolyase breaks the ring formed between the dimers to restore the two thymine residues.

TLS Online TPP Program

#Id: 4985

#Unit 6. System Physiology – Plant

The ratio of red light (R) to far-red light (FR) varies remarkably in different environments. This ratio can be defined as follows: