Diffen âº Science âº Biology âº Microbiology. Fraternal twins are âdizygotic,â meaning that they developed from two different eggs fertilized by two different sperm cells, while identical twins are âmonozygoticâ i.e., they developed from a single fertilized egg that split.
A T-tubule (or transverse tubule) is a deep invagination of the sarcolemma, which is the plasma membrane of skeletal muscle and cardiac muscle cells.These invaginations allow depolarization of the membrane to quickly penetrate to the interior of the cell.ransverse tubules are invaginations of the sarcolemma. Though the invaginations are normally perpendicular to the length of the fiber, many T-tubules can lie axial to the long-axis of the fiber, both wrapping around and running alongside myofilament bundles.
Describe the events that must occur in the muscle cell before calcium is released from this organelle. 3. Jaw muscle contraction (masseter spasm) is one of the key physical findings seen in Davidâs case of malignant hyperthermia.Explain how calcium functions to cause contraction of a skeletal muscle cell.4. Dr. Hodges notes that Davidâs exhaled carbon dioxide levels are elevated.aw muscle contraction (masseter spasm) is one of the key physical findings seen in Davidâs case of malignant hyperthermia. Explain how calcium functions to cause contraction of a skeletal muscle cell. 4. Dr. Hodges notes that Davidâs exhaled carbon dioxide levels are elevated.