Petri (the person that invented the Petri dish) invented the transparent glass lidded dishes which were meant for keeping and growing bacteria and other stuff including fungi and mosses sterilized. It dated back to the late 1800s.
The cytoplasm, ribosomes, plasma membrane, and cell wall can be found in the both eukaryotic and prokaryotic cells.
hen you approach a tree with the intention of accurately identifying it, it is best to focus on the following set of characteristics:
<span>RangeHabitatBarkLeavesTwigsFlowersFruits and Seeds</span>
Answer:
The source of Calcium (Ca⁺⁺) for the skeletal muscle cells is the sarcoplasmic reticulum, the main store of intracellular Ca⁺⁺.
Explanation:
Calcium (Ca⁺⁺) is an ion that plays an important role in muscle contraction, a process that requires high cytoplasmic concentrations of this ion to promote myofibrillary activity.
The sarcoplasmic reticulum (SR) -equivalent to the endoplasmic smooth reticulum- is an organelle that regulates the contractile activity of skeletal muscle. The two terminal cisterns of the SR attach to the T-tube, forming a triad, which surrounds the myofibrilla.
Once the muscle cell receives the signal to contract, the Ca⁺⁺ channels are opened and allow Ca⁺⁺ to enter the cell, promoting the exit of this cation from the SR and increased its cytoplasmic levels. This stimulates muscle contraction.
