24/25 - U3L3 Muscle Contractions Quiz Review

Match the following:

• troponin

• • location on actin molecule that binds to the myosin head during cross-bridge formation.

• myosin

• • a protein connected to troponin that prevents myosin from binding to acing when calcium is not present - covers the myosin binding site.

• tropomyosin

• • Calcium dependent molecule that “shifts” tropomyosin away from the myosin binding site during contraction.

• Actin

• • a protein that makes up most of the thin filament. Binds with myosin head.

• myosin binding site (on actin)

• • ATP dependent protein that binds to actin during cross-bridge formation and pulls the thin filament towards the M-line.

Match the following

• A-Band

• • the boundary of a sarcomere anchored to the thick filament by titin.
    

• Z-line

• • “mid-line” of the sarcomere that anchors the thick filaments. During contraction the thin filaments move towards the m-line.

• I-band

• • spans thick filaments only that shrinks during contraction and lengthens during relaxation.

• M-Line

• • span that includes the thin filaments and z-lines that shortens during contraction and lengths during relaxation.

• H-zone

• • spans the length of the thick filament (myosin). Does not change during contraction.

Match the following

• Axon Knob

• • a neurotransmitter that opens protein channels on the

    sarcolemma.

• Exocytosis

• • an opening of the sarcolemma that allows for the electrical impulse to travel to the sarcoplasmic reticulum

• Synaptic cleft

• • the space between the con terminal bud and the sarcolemma.

• T-Tubules

• • the process of a vesicle fusing with a cell’s membrane to release chemical substances into the extracellular environment.

• Acetylcholine

  (Ach

• • the end of a nerve cell.

Reorder the following steps (1-5) of a muscle contraction

• Nerve Impulse reaches Neuromuscular Junction

• ACH binds to Muscle Receptor Sites

• Action Potential charge travels down muscle cell

• Acetylcholine (ACH) Released by Motor Neuron

• Impulses reaches the SR and Ca+ channels open

Reorder the following (6-10) of the muscle contraction

• Ca+ ions diffuse from the SR and bind to troponin molecules

• The muscle fiber shortens as contractions occurs

• Actin filaments are pulled toward the center of the sarcomere by pulling of the cross-bridges, increasing the overlap of the thin and thick filaments

• Cross-bridges form, linking actin and myosin

• Tropomyosin molecules move and expose specific sites on actin where myosin heads can bind

Which is more true to cause muscle contraction?

• Actin Pulls on the myosin
• Myosin Pulls on the Titin
• Myosin Pulls on Actin
• Actin Pulls on Titin

Which ion, when present, changes the conformation of tropomyosin?

• Calcium
• Sodium
• Potassium
• Lithium

In order for tropomyosin to change conformation, calcium has to bind with...

• Voltage Gated Ion Channel
• Ligand Gated Ion Channel
• Troponin Protein
• Actin Protein

What opens the Calcium Ion Transport Channel embedded in the pre-synaptic terminal?

• Binding of Acetylcholine
• Binding of Calcium Ion
• An Action Potential
• Binding of Sodium Ion

Calcium that will eventually enter the muscle cell to bind with troponin is stored in the...

• T-Tubule of the Muscle Cell
• Sarcoplasmic Reticulum of the Muscle Cell
• The Sarcolemma of the Muscle Cell
• The interstitial space outside the muscle cell near the pre-synaptic terminal.