To see metaphase I animated, click the Play button. The centrioles are at opposite poles of the cell. The pairs of homologous chromosomes (the bivalents), now as tightly coiled and condensed as they will be in meiosis<span>, become arranged on a plane equidistant from the poles called the metaphase plate.</span>
Answer:
The correct answer is True
Explanation:
<u>The first step in glycogen synthesis (glycogenesis) is the phosphorylation of glucose to form glucose-6-phosphate</u>, which is catalyzed by hexokinase. [This step is also the first step in the glycolytic pathway]. Glucose-6-phosphate is then isomerized to glucose-1-phosphate by the action of phosphoglucomutase. This glucose-i-phosphate is then converted to glycogen by glycogen synthase.
Answer and Explanation:
In homeostatic control processes any deviation from the norm sets into motion the appropriate corrective mechanisms which restore the norm. This rectification occurs through negative feedback. When you go outside wearing a sweater on a hot day, the body sends messages to the CNS and the following occurs:
- The superficial blood vessels vasodilate so that more blood flows near the surface. This encourages heat loss.
- Sweating and panting. Sweat secreted by the sweat glands evaporate from the surface of the body as it absorbs latent heat.
- The metabolic rate falls so that the body generates less heat. You also become less active
- Behavioural response by seeking cooler areas, cold drinks or removal of the sweater.
Answer and Explanation:
In rest, attraction strengths between myosin and actin filaments are inhibited by the tropomyosin. When the muscle fiber membrane depolarizes, the action potential caused by this depolarization enters the t-tubules depolarizing the inner portion of the muscle fiber. This activates calcium channels in the T tubules membrane and releases calcium into the sarcolemma. At this point, tropomyosin is obstructing binding sites for myosin on the thin filament. When calcium binds to the troponin C, the troponin T alters the tropomyosin by moving it and then unblocks the binding sites. Myosin heads bind to the uncovered actin-binding sites forming cross-bridges, and while doing it ATP is transformed into ADP and inorganic phosphate which is released. Myofilaments slide impulsed by chemical energy collected in myosin heads, producing a power stroke. The power stroke initiates when the myosin cross-bridge binds to actin. As they slide, ADP molecules are released. A new ATP links to myosin heads and breaks the bindings to the actin filament. Then ATP splits into ADP and phosphate, and the energy produced is accumulated in the myosin heads, which starts a new binding cycle to actin. Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.
