exam 4 Flashcards
locomotion
movement of an organism under its own
power
The cost of locomotion for running, flying, and
swimming animals decreases
with body mass
Vertebrate skeletal and cardiac muscle tissue is made of long, slender cells called
muscle fibers
Each muscle fiber has many threadlike, contractile structures called
myofibrils
myofibrils are striated due to alternating light-dark units
called
sarcomeres
sarcomeres shorten=
myofibrils contract
sarcomeres lengthen =
myofibrils relax
Muscle cells contain many ____, which contain
many sarcomeres
myofibrils
Sarcomere made up of two types of proteins: what are they and what do they do
- Actin: composes thin filaments
- Myosin: composes thick filaments
Thin actin filaments are composed of 2 coiled chains of actin:
One end is anchored to the Z disk, which forms the wall
between sarcomeres
* The other end is free to interact with thick filaments
z disk in thin actin filaments
forms the wall
between sarcomeres
contraction of sarcomere
The filaments slide past one another
- The sarcomere shortens with no change
in lengths of the thin and
thick filaments themselves
myosin’s “Head” binds ___ and actin
ATP
myosin head can bind to actin
head which
catalyzes hydrolysis of ATP
ATP binding releases
actin and myosin
rigor mortis
myosin and actin
locked together after an animal dies.
ATP required for myosin to release
actin.
step 1 of myosin and actin interaction
ATP binds to myosin head, causing conformation change, releasing head from actin.
step 2 of myosin and actin interaction
When ATP is hydrolyzed, myosin head pivots and binds to new actin subunit farther down thin filament
step 3 of myosin and actin interaction
When inorganic phosphate is released, head pivots back to original conformation. Power stroke moves entire thin filament relative to thick filament
step 4 of myosin and actin interaction
ADP is released, and myosin head is ready to bind to
another ATP
Thin filaments also contain proteins what are they and what do they regulate
troponin and tropomyosin. regulate muscle activity
also work together to block myosin binding
sites on actin
the 4 steps of myosin and actin interaction is called what
sliding filament model
classes of muscles
Multivariate vs. Univariate:
Multivariate = multiple nucleus
Univariate = single nucleus
classes of muscles
Striated versus unstriated
Striated = striped appreance (e.g., skeletal muscles)
Unstriated = smooth appreance (e.g., smooth)