The action potential spreads throughout the myocardium in the following sequence: SA node  Atrial internodal tracts and atria  AV node  Bundle of His  Purkinje system  Ventricles

TLS Online TPP Program

#Id: 2865

#Unit 13. Methods in Biology

The most useful range for proteins is above 230 nm, where there are absorptions from aromatic side chains.

TLS Online TPP Program

#Id: 2866

#Unit 13. Methods in Biology

A very weak absorption maximum of phenylalanine occurs at 257 nm, tyrosine and tryptophan dominate the typical protein spectrum with their absorption maxima at 274nm and 280 nm, respectively.

TLS Online TPP Program

#Id: 2867

#Unit 13. Methods in Biology

Cystine (Cys2) possesses a weak absorption maximum of similar strength as phenylalanine at 250 nm.

TLS Online TPP Program

#Id: 2868

#Unit 13. Methods in Biology

The absorption of UV light by nucleic acids arises from n ® p* and p ® p* transitions of the purine and pyrimidine bases that occur between 260nm and 275 nm.

TLS Online TPP Program

#Id: 2869

#Unit 13. Methods in Biology

The absorption spectra of the bases in polymers are sensitive to pH and greatly influenced by electronic interactions between bases.

TLS Online TPP Program

#Id: 2870

#Unit 13. Methods in Biology

The characteristic absorption parameter for the sample is the extinction coefficient a, yielding the correlation I= I0e-ad.