GMS 6474 final exam ACTUAL
QUESTIONS AND CORRECT ANSWERS
what does the SR store - CORRECT ANSWERS proteins and calcium
what is the role of the transverse tubules in the muscle fiber - CORRECT
ANSWERS allow inside of muscle to communicate with the outside of
the muscle
how is a sarcomere measured - CORRECT ANSWERS from z-disc to z-
disc
what is contained in the I band of the sarcomere & what color is the band -
CORRECT ANSWERS thin filaments
titin
z-disc
light (isotropic)
what is contained in the A band of the sarcomere & what color is the band -
CORRECT ANSWERS thick filaments
thin filaments
dark (scatters light)
what is contained in the H zone & what color is the band - CORRECT
ANSWERS thick filaments
light
no barbs or myosin
middle zone of the sarcomere
,what is contained in the M line - CORRECT ANSWERS in the middle of
the sarcomere, middle of H zone
thick filaments
myomesin
what does titin do in the sarcomere - CORRECT ANSWERS structural
protein
how many zones can you see when the sarcomere is relaxed - CORRECT
ANSWERS all zones can be seen in relaxed state
how many zones can be seen when the sarcomere is contracted - CORRECT
ANSWERS sarcomere shortens
I band shortens
H zone disappears
thick and thin filaments overlap DONT shorten
what is the contractile unit of skeletal muscle - CORRECT ANSWERS
the sarcomere
what is the main component of the thick filaments - CORRECT ANSWERS
myosin
have heavy and light chains
motor heads that move it along the thin filament
what is the largest protein in the body - CORRECT ANSWERS titin
what are the main components of the thin filaments - CORRECT ANSWERS
actin (where myosin binds)
,troponin (moves tropomyosin when Ca2+ is present)
tropomyosin (covers actin active site)
nebulin (sets thin filament length)
CapZ (anchors actin to Z-line on z-disc side)
Tropomodulin (on end of actin, in middle of sarcomere)
alpha-actinin (anchors actin to z-line)
what does desmin do in the sarcomere - CORRECT ANSWERS interacts
with alpha-actinin to anchor z-disc to sarcolemma
what does dystrophin do in the sarcomere - CORRECT ANSWERS
connects sarcomere to sarcolemma
stabilizes the sarcolemma to prevent damage during contractions
1st step of cross-bridge cycle - CORRECT ANSWERS BINDING
activated myosin binds to actin
ADP and Pi are still bound to myosin
2nd step of cross bridge cycle - CORRECT ANSWERS POWER
STROKE
myosin head swivels
movement of actin filament
ADP and Pi released from myosin
(Pi is released first, before ADP is released)
3rd step of cross bridge cycle - CORRECT ANSWERS
DISSOSCIATION
ATP binds to myosin
, Actin and myosin dissociate (cross bridge detaches)
4th step of cross bridge cycle - CORRECT ANSWERS ACTIVATION
ATP hydrolysis energy activates myosin head
ADP and Pi remain bound to myosin
if Ca2+ still present, cycle continues
how does Ca2+ effect the cross bridge cycle - CORRECT ANSWERS
Ca2+ is needed for the troponin to move the tropomyosin off the actin
when Ca2+ runs out, the cross bridge cycle will stop
troponin has 4 Ca2+ binding sites
how does Ca2+ get into the cell to trigger the cross bridge cycle - CORRECT
ANSWERS through the RyR channels, which are activated by the DHPR
channel mechanical change IN SKELETAL MUSCLES
what are the two roles of ATP in the cross bridge cycle - CORRECT ANSWERS
release from rigor state
re-energize/reactivate myosin heads for next cycle
what resequesters Ca2+ to end muscle contraction - CORRECT ANSWERS
SERCA
where is the sarcoplasmic reticulum located - CORRECT ANSWERS
wrapped around the sarcomeres and throughout the myofibrils
what is the role of the sarcoplasmic reticulum in muscle cells - CORRECT
ANSWERS stores Ca2+ that is needed for contraction
QUESTIONS AND CORRECT ANSWERS
what does the SR store - CORRECT ANSWERS proteins and calcium
what is the role of the transverse tubules in the muscle fiber - CORRECT
ANSWERS allow inside of muscle to communicate with the outside of
the muscle
how is a sarcomere measured - CORRECT ANSWERS from z-disc to z-
disc
what is contained in the I band of the sarcomere & what color is the band -
CORRECT ANSWERS thin filaments
titin
z-disc
light (isotropic)
what is contained in the A band of the sarcomere & what color is the band -
CORRECT ANSWERS thick filaments
thin filaments
dark (scatters light)
what is contained in the H zone & what color is the band - CORRECT
ANSWERS thick filaments
light
no barbs or myosin
middle zone of the sarcomere
,what is contained in the M line - CORRECT ANSWERS in the middle of
the sarcomere, middle of H zone
thick filaments
myomesin
what does titin do in the sarcomere - CORRECT ANSWERS structural
protein
how many zones can you see when the sarcomere is relaxed - CORRECT
ANSWERS all zones can be seen in relaxed state
how many zones can be seen when the sarcomere is contracted - CORRECT
ANSWERS sarcomere shortens
I band shortens
H zone disappears
thick and thin filaments overlap DONT shorten
what is the contractile unit of skeletal muscle - CORRECT ANSWERS
the sarcomere
what is the main component of the thick filaments - CORRECT ANSWERS
myosin
have heavy and light chains
motor heads that move it along the thin filament
what is the largest protein in the body - CORRECT ANSWERS titin
what are the main components of the thin filaments - CORRECT ANSWERS
actin (where myosin binds)
,troponin (moves tropomyosin when Ca2+ is present)
tropomyosin (covers actin active site)
nebulin (sets thin filament length)
CapZ (anchors actin to Z-line on z-disc side)
Tropomodulin (on end of actin, in middle of sarcomere)
alpha-actinin (anchors actin to z-line)
what does desmin do in the sarcomere - CORRECT ANSWERS interacts
with alpha-actinin to anchor z-disc to sarcolemma
what does dystrophin do in the sarcomere - CORRECT ANSWERS
connects sarcomere to sarcolemma
stabilizes the sarcolemma to prevent damage during contractions
1st step of cross-bridge cycle - CORRECT ANSWERS BINDING
activated myosin binds to actin
ADP and Pi are still bound to myosin
2nd step of cross bridge cycle - CORRECT ANSWERS POWER
STROKE
myosin head swivels
movement of actin filament
ADP and Pi released from myosin
(Pi is released first, before ADP is released)
3rd step of cross bridge cycle - CORRECT ANSWERS
DISSOSCIATION
ATP binds to myosin
, Actin and myosin dissociate (cross bridge detaches)
4th step of cross bridge cycle - CORRECT ANSWERS ACTIVATION
ATP hydrolysis energy activates myosin head
ADP and Pi remain bound to myosin
if Ca2+ still present, cycle continues
how does Ca2+ effect the cross bridge cycle - CORRECT ANSWERS
Ca2+ is needed for the troponin to move the tropomyosin off the actin
when Ca2+ runs out, the cross bridge cycle will stop
troponin has 4 Ca2+ binding sites
how does Ca2+ get into the cell to trigger the cross bridge cycle - CORRECT
ANSWERS through the RyR channels, which are activated by the DHPR
channel mechanical change IN SKELETAL MUSCLES
what are the two roles of ATP in the cross bridge cycle - CORRECT ANSWERS
release from rigor state
re-energize/reactivate myosin heads for next cycle
what resequesters Ca2+ to end muscle contraction - CORRECT ANSWERS
SERCA
where is the sarcoplasmic reticulum located - CORRECT ANSWERS
wrapped around the sarcomeres and throughout the myofibrils
what is the role of the sarcoplasmic reticulum in muscle cells - CORRECT
ANSWERS stores Ca2+ that is needed for contraction
