Cell Biology Lab Exam 3

Front 1

Skeletal muscles consist of muscle fibers made of bundles of ___________.

Back 1

multinucleated cells

Front 2

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

Back 2

Sarcomeres

Front 3

I bands are composed entirely of _________.

Back 3

actin thin filaments

Front 4

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

Back 4

40; 10-50

Front 5

Skeletal muscle cells contain bundles of ______.

Back 5

myofibrils

Front 6

______ are the basic units of contraction.

Back 6

sarcomeres

Front 7

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

Back 7

thick filaments; thin filaments

Front 8

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

Back 8

19%; 35%

Front 9

Skeletal muscle is sometimes referred to as ________.

Back 9

striated muscle

Front 10

Thick filaments extend the entire length of the ____ band.

Back 10

A

Front 11

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

Back 11

H zone

Front 12

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

Back 12

H zone

Front 13

a band running down the center of the H zone

Back 13

M band

Front 14

The __ band contains only thin filaments.

Back 14

I

Front 15

A dense line in the center of the I band.

Back 15

Z disc

Front 16

A sarcomere extends from one _____ to the next.

Back 16

Z disc

Front 17

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

Back 17

ATP and Calcium; positive

Front 18

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.

Back 18

shortening

Front 19

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

Back 19

inward

Front 20

Parts that change in dimension during contraction: (3)

Back 20

sarcomere, I band, H band

Front 21

The ____ band does not change during contraction.

Back 21

A

Front 22

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

Back 22

2; 4

Front 23

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

Back 23

LMM and S2; S1 motor domain

Front 24

The head domain of myosin possesses _____ and the ______.

Back 24

ATPase activity; actin binding site

Front 25

Myosin II dimerizes by forming a ____________.

Back 25

coiled coil domain

Front 26

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

Back 26

300-400

Front 27

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

Back 27

sarcoplasmic reticulum

Front 28

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

Back 28

transvers tubule

Front 29

_____ is a protein complex that is bound to tropomyosin.

Back 29

troponin

Front 30

Thin filaments contain _____ and _______.

Back 30

tropomyosin and troponin

Front 31

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

Back 31

tropomyosin

Front 32

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

Back 32

calcium; tropomyosin

Front 33

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

Back 33

smooth muscle

Front 34

Contraction in smooth muscles is ________.

Back 34

involuntary

Front 35

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

Back 35

smooth muscle

Front 36

_______ is found only in the heart.

Back 36

cardiac muscle

Front 37

______ is composed of uninucleate cells bound together at dense plaques called intercalated discs.

Back 37

cardiac muscle

Front 38

_____ appears to be striated, or striped, because of the parallel arrangements of the bundles of contractile fibers.

Back 38

cardiac muscle

Front 39

The contraction in cardiac muscle is ______.

Back 39

involuntary

Front 40

The contraction in skeletal muscles is ________.

Back 40

voluntary

Front 41

kinase to be tested

Back 41

PKA

Front 42

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

Back 42

PepTag

Front 43

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

Back 43

reaction buffer

Front 44

cAMP activates ____

Back 44

PKA

Front 45

solution that maintains PKA activity

Back 45

PKA dilution buffer

Front 46

The phosphorylated peptide moves toward the ______.

Back 46

cathode (+)

Front 47

The nonphosphorylated peptide moves toward the _______.

Back 47

anode (-)

Front 48

a significant step in intracellular signal transduction is the activation of _________.

Back 48

protein kinases

Front 49

3 amino acids that can be phosphorylated:

Back 49

serine, threonine, tyrosine