Question

Imagine that a researcher has dissected out a single muscle bundle from a triceps muscle biopsy. She sections this bundle and stains it for a variety of muscle-associated proteins. After staining, when the researcher zooms in on a sarcomere, she notices that a certain protein always dots the periphery along the length of the thin filaments. This protein is most likely:

Answer 1

Troponin or tropomyosin is the protein likely seen dotting the periphery along the length of the thin filaments in a sarcomere, which is the functional unit of a muscle fiber.

Step-by-step explanation:

The protein that dots the periphery along the length of the thin filaments in a sarcomere is most likely troponin or tropomyosin, as they are the regulatory proteins associated with the actin filaments. These proteins are essential for muscle contraction as they control the interaction of actin and myosin, the two main contractile proteins in muscle fibers. The sarcomere, bordered by Z-discs, contains the thin filaments made of actin and these regulatory proteins which appear as dots along the edges when stained and viewed under high magnification.

Answer 2

Tropomyosin

Step-by-step explanation:

This protein is most likely: Tropomyosin.

Sacromere is the structural unit of myofibrils i.e. the fibres of the muscles.

Tropomyosin is the muscle protein that function in contraction of muscle filaments.They are arranged laterally along the myofilament. When the researcher is observing the sacromere, she is observing the muscle fibre. So, the protein that lines the periphery along the thin filament is more likely to be tropomysin.