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50 Cards in this Set
- Front
- Back
Skeletal muscles consist of muscle fibers made of bundles of ___________.
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multinucleated cells |
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Each multinucleated cell in skeletal muscle contains a bundle of myofibrils, which consist of thousands of repeating contractile structures called __________.
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Sarcomeres
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I bands are composed entirely of _________. |
actin thin filaments |
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Skeletal muscle cells are _____ mm long and ____ um wide.
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40; 10-50 |
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Skeletal muscle cells contain bundles of ______. |
myofibrils |
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______ are the basic units of contraction. |
sarcomeres |
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Each sarcomere contains ________ composed of myosin II and ________ composed of single actin filaments and associated proteins. |
thick filaments; thin filaments |
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In rabbit muscle, actin is ____ of total protein while myosin II is _____. |
19%; 35% |
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Skeletal muscle is sometimes referred to as ________.
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striated muscle |
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Thick filaments extend the entire length of the ____ band.
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A |
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Thick and thin filaments overlap in the A band except in the central region called the ______. |
H zone |
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The _____ is the region in the center of the A band where there are no thin filaments. |
H zone |
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a band running down the center of the H zone |
M band |
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The __ band contains only thin filaments. |
I |
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A dense line in the center of the I band. |
Z disc |
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A sarcomere extends from one _____ to the next. |
Z disc |
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In the presence of ____ and ____, the myosin heads extending from the thick filaments walk toward the _____ ends of the thin filaments.
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ATP and Calcium; positive |
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Because the thin filaments are anchored at the Z disks, movement of myosin pulls the actin filaments toward the center of the sarcomere, _________ its length in the contracted state.
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shortening |
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During contraction, thin filaments slide ______ over the thick filaments.
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inward |
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Parts that change in dimension during contraction: (3)
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sarcomere, I band, H band |
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The ____ band does not change during contraction.
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A |
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Myosin II molecules consist of ___ identical heavy chains and ____ light chains.
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2; 4 |
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Limited proteolytic cleavage of myosin II generates tail fragments ___ and ___ and the _________.
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LMM and S2; S1 motor domain |
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The head domain of myosin possesses _____ and the ______.
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ATPase activity; actin binding site |
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Myosin II dimerizes by forming a ____________.
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coiled coil domain
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A thick filament in a muscle cell contains _____ myosin II molecules that associate via the tail domains. |
300-400 |
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The ____________ regulates the level of free Ca2+ in myofibrils.
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sarcoplasmic reticulum |
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When a nerve impulse stimulates a muscle cell, the action potential is transmitted down a _________.
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transvers tubule |
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_____ is a protein complex that is bound to tropomyosin.
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troponin |
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Thin filaments contain _____ and _______.
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tropomyosin and troponin |
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In the relaxed state, ______ blocks the sites on actin where crossbridges form between thick and thin filaments.
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tropomyosin |
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During contraction, _____ rises. This in turn causes _____ to change conformation, exposing the sites for cross bridge formation. |
calcium; tropomyosin |
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_______ is composed of sheets of cells, each cell with one nucleus. |
smooth muscle |
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Contraction in smooth muscles is ________.
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involuntary |
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______ is found in the walls of blood vessels, the digestive tract, and the reproductive system. |
smooth muscle |
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_______ is found only in the heart. |
cardiac muscle |
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______ is composed of uninucleate cells bound together at dense plaques called intercalated discs. |
cardiac muscle
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_____ appears to be striated, or striped, because of the parallel arrangements of the bundles of contractile fibers.
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cardiac muscle
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The contraction in cardiac muscle is ______. |
involuntary |
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The contraction in skeletal muscles is ________. |
voluntary |
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kinase to be tested
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PKA |
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short peptide that can be phosphorylates by PKA, peptide is linked to a dye so it can be seen on a gel
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PepTag |
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allow for appropriate reaction conditions; ATP supplies the phosphate that PKA transfers to the PepTag substrate |
reaction buffer |
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cAMP activates ____ |
PKA |
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solution that maintains PKA activity |
PKA dilution buffer |
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The phosphorylated peptide moves toward the ______.
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cathode (+) |
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The nonphosphorylated peptide moves toward the _______.
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anode (-) |
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a significant step in intracellular signal transduction is the activation of _________.
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protein kinases |
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3 amino acids that can be phosphorylated:
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serine, threonine, tyrosine
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