Anything prokaryotic doesn't contain a nucleus
The important point is that the surface area to the volume ratio gets smaller as the cell gets larger and as volume increases, surface area to volume ratio decreases. The larger a cell, the less easily it can get rid of waste and it also has more trouble getting water, nutrients and gases in. That is why we do not see giant cells. Instead we see multiple cells in larger organisms.
One way to increase surface area is to flatten the cell. That is why red blood cells are flat discs, instead of spheres. Another way is elongation. That is why many bacteria are rod shaped, and why neurons are elongated. In fact, the human body relies on the same principle to adapt to climate. Long tall and lean folks with long arms and legs live in East Africa, because such shapes increase surface area to get rid of excess body heat to avoid heat strokes. Europeans and Asians adapted to cold climates, in contrast, have shorter arms and legs and rounder torsos to minimize surface area. to conserve body heat.
Answer:
e. bind to troponin which moves the tropomyosin.
Explanation:
Troponin (Tn) is a protein complex composed of three different proteins: troponin C (TnC), troponin I (TnI), and troponin T (TnT). This complex is found both in skeletal muscles and cardiac muscles, where TnC attaches calcium ions through four and three calcium ion-binding sites, respectively. When a muscle is relaxed, Tn attaches to tropomyosin to prevent muscle contraction. During muscle contraction, calcium channels open and cytosolic calcium ions bind to TnC, thereby Tn changes its conformation and moves the tropomyosin. This process relieves the inhibition of the interaction between actin and myosin filaments, which makes muscle contraction possible.
