Final answer:
The dark A bands and light I bands on a myofibril are responsible for the striated appearance of skeletal muscle tissue. The A bands consist of overlapping actin and myosin filaments, while the I bands mainly consist of actin filaments. These bands repeat along myofibrils, giving the muscles their banded appearance.
Step-by-step explanation:
The striated appearance of skeletal muscle tissue is a result of alternating bands of the proteins actin and myosin that occur along the length of myofibrils. The dark bands, called A bands, consist of overlapping thin and thick filaments of actin and myosin. The light bands, called I bands, mainly consist of thin actin filaments. These bands repeat along myofibrils and give skeletal muscles their striated or banded appearance.