The endoplasmic reticulum is the term which describes an extensive network of tubes, sacs, and vesicles throughout a cell that provides transport as its main function. The endoplasmic reticulum is a small organelle and is found in most Eukaryotic cells. It is not found in red blood cells. The endoplasmic reticulum is a network in the core of the cell and occurs within the nuclear membrane and is involved in the synthesis of lipids and proteins. The endoplasmic reticulum also usually has ribosomes attached to it.
All viruses rely on themselves
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Answer:
When a muscle cell contracts, the myosin heads each produce a single power stroke.
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, <em>tropomyosin is obstructing binding sites for myosin on the thin filament</em>. 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 liberated. Myofilaments slide impulsed by chemical energy collected in myosin heads, <u>producing a power stroke</u>. 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.
Answer:
d. Fire ants spread by winged members and by hitching rides so a single colony can cause infestation.
Explanation:
An invasive fire ant colony can be very disastrous to the population of organisms in a locality. They cause massive competition with the native species thereby infesting them and destroying the native population.
Fire ants spread by winged members which makes a single colony to cause severe damage to the native specie. Often times, as they become endemic, they manifest as the dominant specie in a particular location.
