Chapter 8, Problem 6AYK

Figure 38.37 Which of the following statements about muscle contraction is true? The power stroke occurs when ATP is hydrolyzed to ADP and phosphate. The power stroke occurs when ADP and phosphate dissociate from the myosin head. The power stroke occurs when ADP and phosphate dissociate from the actin active site. The power stroke occurs when Ca2+ binds the calcium head.

Skeletal muscle contraction requires _________. a. calcium ions b. ATP c. arrival of a nerve impulse d. all of the above

Indicate in which category, transcription or translation, each of the following functions belongs: RNA poly-merase, ribosomes, nucleotides, tRNA, pre-mRNA, DNA, anticodon, amino acids.

Depolarization of the sarcolemma means ________. the inside of the membrane has become Less negative as sodium ions accumulate the outside of the membrane has become less negative as sodium ions accumulate the inside of the membrane has become more negative as sodium ions accumulate the sarcolemma has completely lost any electrical charge

Figure 38.38 The deadly nerve gas Sarin irreversibly inhibits acetycholinesterase. What effect would Sarin have on muscle contraction?

In 2003, the Nobel Prize in Physiology or Medicine was awarded to Paul C. Lauterbur and Sir Peter Mansfield for discoveries related to magnetic resonance imaging (MRI). This is a tool to see the structures of the body (not just the nervous system) that depends on magnetic fields associated with certain atomic nuclei. The utility of this technique in the nervous system is that fat tissue and water appear as different shades between black and white. Because white matter is fatty (from myelin) and gray matter is not, they can be easily distinguished in MRI images. Visit the Nobel Prize website (http://openstaxcollege.org/l/nobel_2) to play an interactive game that demonstrates the use of this technology and compares it with other types of imaging technologies. Also, the results from an MRI session are compared with images obtained from x-ray or computed tomography. How do the imaging techniques shown in this game indicate the separation of white and gray matter compared with the freshly dissected tissue shown earlier?

Why do you think a person is able to perform anaerobic exercise (such as lifting and holding a heavy weight) only briefly but can sustain aerobic exercise (such as walking or swimming) for long periods? (Hint: Muscles have limited energy stores.)

A patient undergoing an MRI is surrounded by a tubeshaped scanner. Watch this video (http://openstaxcollege.org/l/MRI) to learn more about MRIs. What is the function of magnets in an MRI?

Some desperate cancer patients consume pills or other preparations containing shark cartilage, which the manufacturers tout as an anti-angiogenesis compound. The basis for these claims is the fact that blood vessels do not grow into cartilage. Responsible researchers point out that, regardless of the properties of cartilage, there is no way that eating it could provide any anticancer benefit. Why is this counterargument correct?