One cardiac cycle is .8 seconds. A complete heartbeat is produced in one cardiac cycle. <span>The period of time that begins with contraction of the atria and ends with ventricular relaxation is known as the cardiac cycle. The period of contraction that the heart undergoes while it pumps blood into circulation is called systole.</span>
Proteins are macromolecules that are made up of the subunits that are called amino acids, there are 20 fundamental kinds of amino acids present. These varying combinations of them make different proteins needed for numerous functions.
The Nucleus is sort of like the "brain" of a cell.
NUCLEAR FUSION, hope it helps
