FINAL EXam Flashcards
Anabolism
refers to the metabolic pathways that synthesize complex molecules from simpler ones, using energy
example: making glucose from photosynthesis; proteins from amino acids
- requires energy
catabolism
refers to the metabolic pathways that break down complex molecules to simpler ones, releasing energy
example: cellular respiration(breaking down glucose)
- gives off energy
what is metabolic rate affected by?
Eactivity= altered skeletal muscle activity- exercise needs energy
- food-induced thermogenesis- digestion, absorption and use of stores
201
How does size effect metabolic rate?
the bigger you get metabolic rate drops since you can store more energy than a smaller animal
- the smaller you get the more energy use per gram less energy efficient
when grouping organisms together what is the overall slope of the graph
0.75 .
what is mass-specific?
resting metabolic rate scale with mass
what certain factors affect muscles and the force/production of movement and how?
- # of muscle cells in the tissue
- length of the muscle
- speed of contraction
- the force generated by any muscle will increase as you increase the:
-# of muscle cells in the tissue
- length of the muscle
The force generated by any muscle will decrease with the speed of contraction
a muscle is a bundle of what?
muscle fibres
during growth what takes place inside the cell?
hundreds of myoblasts fish to form a long, multi-nucleate cell
muscle fibres are filled with bundles of
myofibrils
myofibrils consists of stacks of what?
alternating thick and thin filaments
how are the thick and thin filaments in a myofibril organized?
they are arranged along the length of the myofibril in sarcomeres, which are the functional unit of muscles
under a microscope myofibrils appear what?
striated
what are the thin filaments in a muscle?
- actin: these wrap around each other in a helical manner
- tropomyosin: this is a long, rope-like protein that winds around the actin filament. It acts as a regulatory protein by blocking the binding sites for the myosin (thick filament) on the actin molecules
- troponin : this is a complex of three proteins that attach to tropomyosin. It plays a crucial role in muscle contraction by responding to calcium ions, which results in a change in the position of the tropomyosin, thereby exposing the binding sites for myosin
what are the thick filaments in a muscle?
- myosin
each myosin protein is a dimer of two polypeptides coiled around each other with a globular “head” at one end and a long helical “tail”
- dozens of myosin homodimers are arranged into thick muscle filaments with the head group sticking “out”
Each myosin head domain has?
ATP binding site: this is where ATP binds to the myosin head.
- Actin binding site :This site on the myosin head is where it attaches to the actin filament. When myosin binds to actin, it forms a cross-bridge, allowing the myosin head to pull on the actin filament, which contributes to muscle contraction.
Power Stroke Mechanism: The myosin head undergoes a conformational change after the ATP is hydrolyzed into ADP and phosphate. This change moves the head in a way that pulls the actin filament toward the center of the sarcomere, known as the power stroke. After the power stroke, ADP and phosphate are released from the myosin head, resetting it for a new cycle of muscle contraction.
what is a crossbridge?
the interaction between an actin protein and a myosin head group
what is the key thing when thinking about contraction in the sliding filament theory?
actin filaments do not get shorter
myosin filaments do not get shorter
what get shorter is the length of the sarcomere
- when muscle is fully contracted there is a massive overlap of actin+myosin
what is the sarcoplasmic reticulum?
- surrounds the myofibrils, which are the contractile units made up of sarcomeres
- this is where calcium is stored. When the muscle is relaxed, the SR stores calcium ions lowering the concentration in the cytosol
- when the there is a release of the calcium it is moved into the cytosol. this triggers the interaction of actin and myosin.
- after contraction calcium ions are pumped back into the SR, which helps muscle to relax
explain how muscle contraction is activated?
when a signal is received the motor neurone
1. opens ca- channels through facilatated diffusion
- ca ions then diffuse into the myofibril cytoplasm (cytosol)
what happens when the ca2+ enters the cytosol?
- Ca ions bind troponin on the actin filaments
- this causes tropomyosin to shift, exposing myosin-binding sites on the actin
- myosin+actin can now form a cross-bridge
the force generated during a muscle contraction increases when the number of what?
crossbirdges formed on a sarcomere increase
the force generated by any muscle will decrease with speed of contraction TRUE OR FALSE?
true
( rapid contraction decreases # of cross bridges)
The force generated by any muscle will increase as you increase the number of muscle cells in the tissue?TRUE OR FALSE
TRUE( more muscles = more sarcomeres)