Question

(9/25/25) formative assessment assignment: chapter 6 the muscular system part 1 (sugg
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so why are we bothering with all these terms—dark this and light that? because the banding pattern reveals the working structure of the myofibrils. first,
we find that the myofibrils are actually chains of tiny ( 1 ) units called sarcomeres (sarko - mĕrz), which are the structural and functional units of
skeletal muscle. the sarcomeres are aligned end to end like boxcars in a train along the length of the myofibrils. second, it is the precise arrangement of
even smaller structures (myofilaments) within sarcomeres that produces the ( 2 ) in skeletal muscle fibers.
lets examine how the arrangement of the myofilaments leads to the banding pattern. there are two types of threadlike protein myofilaments within each
sarcomere (figure 6 3c). the thick filaments are made mostly of bundled molecules of the ( 3 ) myosin, but they also contain atpase enzymes,
which split atp to release the energy used for muscle contraction. notice that the thick filaments extend the entire length of the dark a band. also, notice
that the midparts of the thick ( 4 ) are smooth, but their ends are studded with small projections (figure 6 3c). these projections, or myosin
heads, form cross bridges when they link the thick and thin filaments together during contraction. myosin filaments are attached to the z discs by titin, ( 5
) filaments that run through the core of the thick filament.

o 1 striations 2 protein 3 filaments 4 elastic 5 contractile

o 1 contractile 2 striations 3 protein 4 filaments 5 elastic

o 1 elastic 2 contractile 3 striations 4 protein 5 filaments

o 1 filaments 2 elastic 3 contractile 4 striations 5 protein

o 1 protein 2 filaments 3 elastic 4 contractile 5 striations

Explanation:

1. Myofibrils are made of contractile units called sarcomeres.
2. The precise arrangement of myofilaments in sarcomeres produces striations in skeletal - muscle fibers.
3. Thick filaments are mainly made of the protein myosin.
4. The mid - parts of thick filaments are smooth.
5. Myosin filaments are attached to Z - discs by elastic titin filaments.

Answer:

1. contractile
2. striations
3. protein
4. filaments
5. elastic