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50 Cards in this Set

  • Front
  • Back
Skeletal muscles consist of muscle fibers made of bundles of ___________.

multinucleated cells
Each multinucleated cell in skeletal muscle contains a bundle of myofibrils, which consist of thousands of repeating contractile structures called __________.

I bands are composed entirely of _________.

actin thin filaments
Skeletal muscle cells are _____ mm long and ____ um wide.

40; 10-50

Skeletal muscle cells contain bundles of ______.


______ are the basic units of contraction.


Each sarcomere contains ________ composed of myosin II and ________ composed of single actin filaments and associated proteins.

thick filaments; thin filaments

In rabbit muscle, actin is ____ of total protein while myosin II is _____.

19%; 35%
Skeletal muscle is sometimes referred to as ________.

striated muscle
Thick filaments extend the entire length of the ____ band.


Thick and thin filaments overlap in the A band except in the central region called the ______.

H zone

The _____ is the region in the center of the A band where there are no thin filaments.

H zone

a band running down the center of the H zone

M band

The __ band contains only thin filaments.


A dense line in the center of the I band.

Z disc

A sarcomere extends from one _____ to the next.

Z disc
In the presence of ____ and ____, the myosin heads extending from the thick filaments walk toward the _____ ends of the thin filaments.

ATP and Calcium; positive
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.

During contraction, thin filaments slide ______ over the thick filaments.

Parts that change in dimension during contraction: (3)

sarcomere, I band, H band
The ____ band does not change during contraction.

Myosin II molecules consist of ___ identical heavy chains and ____ light chains.

2; 4
Limited proteolytic cleavage of myosin II generates tail fragments ___ and ___ and the _________.

LMM and S2; S1 motor domain
The head domain of myosin possesses _____ and the ______.

ATPase activity; actin binding site
Myosin II dimerizes by forming a ____________.
coiled coil domain

A thick filament in a muscle cell contains _____ myosin II molecules that associate via the tail domains.

The ____________ regulates the level of free Ca2+ in myofibrils.

sarcoplasmic reticulum
When a nerve impulse stimulates a muscle cell, the action potential is transmitted down a _________.

transvers tubule
_____ is a protein complex that is bound to tropomyosin.

Thin filaments contain _____ and _______.

tropomyosin and troponin
In the relaxed state, ______ blocks the sites on actin where crossbridges form between thick and thin filaments.


During contraction, _____ rises. This in turn causes _____ to change conformation, exposing the sites for cross bridge formation.

calcium; tropomyosin

_______ is composed of sheets of cells, each cell with one nucleus.

smooth muscle
Contraction in smooth muscles is ________.


______ is found in the walls of blood vessels, the digestive tract, and the reproductive system.

smooth muscle

_______ is found only in the heart.

cardiac muscle

______ is composed of uninucleate cells bound together at dense plaques called intercalated discs.
cardiac muscle
_____ appears to be striated, or striped, because of the parallel arrangements of the bundles of contractile fibers.
cardiac muscle

The contraction in cardiac muscle is ______.


The contraction in skeletal muscles is ________.

kinase to be tested

short peptide that can be phosphorylates by PKA, peptide is linked to a dye so it can be seen on a gel


allow for appropriate reaction conditions; ATP supplies the phosphate that PKA transfers to the PepTag substrate

reaction buffer

cAMP activates ____


solution that maintains PKA activity

PKA dilution buffer

The phosphorylated peptide moves toward the ______.

cathode (+)
The nonphosphorylated peptide moves toward the _______.

anode (-)
a significant step in intracellular signal transduction is the activation of _________.

protein kinases
3 amino acids that can be phosphorylated:
serine, threonine, tyrosine