Rigor mortis sets in after the death of humans and other animals because the supply of ATP decreases to the point at which calcium can no longer be removed from the cell. At this point, the myosin molecules attach to the thin filament. The muscles
stiffen, and limbs cannot be moved. Why and for how long does the muscle then remain in this continuously contracted state?
What will be an ideal response?
If the myosin molecules cannot disengage from the actin filaments (i.e., the cross-bridges cannot be broken), the muscle cannot rebound back to its starting position, and the muscle will stay locked in that position. Eventually, the actin and myosin proteins themselves will break down, and the muscles will be moveable again.
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Stanley Miller constructed an apparatus containing water vapor, hydrogen gas, methane, and ammonia and energized it with electricity in a model of the atmosphere of early Earth. The apparatus produced all of the following choices except ________
a. living cells b. sugars c. amino acids d. organic compounds
Which of the following phrases reflects an effective treatment of biofilms?
A. Interrupt quorum-sensing pathways, preventing signaling between cells B. Pre-treat with newly-discovered antimicrobials before exposure to established drugs C. Add DNase to the antibiotics to disrupt extracellular debris D. All of the above have been shown to enhance biofilm elimination.
For the same sample, the 95% confidence interval will have what relation to the 99% confidence interval?
A. It will be smaller. B. It will be larger. C. They will not overlap. D. They will be exact complements of each other.
Bacterial and archaeal ribosomes are known as ________ ribosomes, based on their sedimentation coefficient.
A. 70S B. 50S C. 30S D. 80S