Name:_____________________ Date:_________________

Name:___________________ Date:_________________

11.2.NOS:  Developments in scientific research follow improvements in apparatus:

Fluorescent calcium ions have been used to study the cyclic interactions in muscle contractions

Describe the use of fluorescence to study muscle contraction.

1. Explain the bioluminescence observed in muscle contraction studies using calcium sensitive aequorin.

AEQUORIN is a protein that glows or bioluminesces in the presence of calcium. It was injected into the muscle fiber of a barnacle. When the muscle fiber was stimulated to contract, it gave off a strong glow of bioluminescence when calcium was released from the sarcoplasmic reticulum to allow for contraction (binding and shifting regulatory proteins). When the stimulation stopped and calcium was taken back up into the SR the glow decreased.

2. Explain the bioluminescence observed in muscle contraction studies using fluorescently tagged myosin molecules.

Researchers used the actin filaments from the long fresh water algae cell Nitella axillaris to view fluorescently labeled myosin globular heads “walk” along the actin threads in the presence of ATP.