GMS 6474 Final Exam Questions with Verified
Correct Answers
what does the SR store
proteins and calcium
what is the role of the transverse tubules in the muscle fiber
allow inside of muscle to communicate with the outside of the muscle
how is a sarcomere measured
from z-disc to z-disc
what is contained in the I band of the sarcomere & what color is the band
thin filaments
titin
z-disc
light (isotropic)
what is contained in the A band of the sarcomere & what color is the band
thick filaments
thin filaments
dark (scatters light)
what is contained in the H zone & what color is the band
thick filaments
light
no barbs or myosin
middle zone of the sarcomere
,what is contained in the M line
in the middle of the sarcomere, middle of H zone
thick filaments
myomesin
what does titin do in the sarcomere
structural protein
how many zones can you see when the sarcomere is relaxed
all zones can be seen in relaxed state
how many zones can be seen when the sarcomere is contracted
sarcomere shortens
I band shortens
H zone disappears
thick and thin filaments overlap DONT shorten
what is the contractile unit of skeletal muscle
the sarcomere
what is the main component of the thick filaments
myosin
have heavy and light chains
motor heads that move it along the thin filament
what is the largest protein in the body
titin
,what are the main components of the thin filaments
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
interacts with alpha-actinin to anchor z-disc to sarcolemma
what does dystrophin do in the sarcomere
connects sarcomere to sarcolemma
stabilizes the sarcolemma to prevent damage during contractions
1st step of cross-bridge cycle
BINDING
activated myosin binds to actin
ADP and Pi are still bound to myosin
2nd step of cross bridge cycle
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
DISSOSCIATION
ATP binds to myosin
Actin and myosin dissociate (cross bridge detaches)
4th step of cross bridge cycle
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
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
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
release from rigor state
re-energize/reactivate myosin heads for next cycle
what resequesters Ca2+ to end muscle contraction
SERCA
where is the sarcoplasmic reticulum located
Correct Answers
what does the SR store
proteins and calcium
what is the role of the transverse tubules in the muscle fiber
allow inside of muscle to communicate with the outside of the muscle
how is a sarcomere measured
from z-disc to z-disc
what is contained in the I band of the sarcomere & what color is the band
thin filaments
titin
z-disc
light (isotropic)
what is contained in the A band of the sarcomere & what color is the band
thick filaments
thin filaments
dark (scatters light)
what is contained in the H zone & what color is the band
thick filaments
light
no barbs or myosin
middle zone of the sarcomere
,what is contained in the M line
in the middle of the sarcomere, middle of H zone
thick filaments
myomesin
what does titin do in the sarcomere
structural protein
how many zones can you see when the sarcomere is relaxed
all zones can be seen in relaxed state
how many zones can be seen when the sarcomere is contracted
sarcomere shortens
I band shortens
H zone disappears
thick and thin filaments overlap DONT shorten
what is the contractile unit of skeletal muscle
the sarcomere
what is the main component of the thick filaments
myosin
have heavy and light chains
motor heads that move it along the thin filament
what is the largest protein in the body
titin
,what are the main components of the thin filaments
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
interacts with alpha-actinin to anchor z-disc to sarcolemma
what does dystrophin do in the sarcomere
connects sarcomere to sarcolemma
stabilizes the sarcolemma to prevent damage during contractions
1st step of cross-bridge cycle
BINDING
activated myosin binds to actin
ADP and Pi are still bound to myosin
2nd step of cross bridge cycle
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
DISSOSCIATION
ATP binds to myosin
Actin and myosin dissociate (cross bridge detaches)
4th step of cross bridge cycle
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
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
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
release from rigor state
re-energize/reactivate myosin heads for next cycle
what resequesters Ca2+ to end muscle contraction
SERCA
where is the sarcoplasmic reticulum located
