Answer:
- Calcium binds to troponin C
- Troponin T moves tropomyosin and unblocks the binding sites
- Myosin heads join to the actin forming cross-bridges
- ATP turns into ADP and inorganic phosphate and releases energy
- The energy is used to impulse myofilaments slide producing a power stroke
- ADP is released and a new ATP joins the myosin heads and breaks the bindings to the actin filament
- ATP splits into ADP and phosphate, and the energy produced is accumulated in the myosin heads, starting a new cycle
- Z-bands are pulled toward each other, shortening the sarcomere and the I-band, producing muscle fiber contraction.
Explanation:
In rest, the tropomyosin inhibits the attraction strengths between myosin and actin filaments. Contraction initiates when an action potential depolarizes the inner portion of the muscle fiber. Calcium channels activate in the T tubules membrane, releasing <u>calcium into the sarcolemma.</u> At this point, tropomyosin is obstructing binding sites for myosin on the thin filament. When calcium binds to troponin C, troponin T alters the tropomyosin position by moving it and unblocking the binding sites. Myosin heads join to the uncovered actin-binding points forming cross-bridges, and while doing so, ATP turns into ADP and inorganic phosphate, which is released. Myofilaments slide impulsed by chemical energy collected in myosin heads, producing a power stroke. The power stroke initiates when the myosin cross-bridge binds to actin. As they slide, ADP molecules are released. A new ATP links to myosin heads and breaks the bindings to the actin filament. Then ATP splits into ADP and phosphate, and the energy produced is accumulated in the myosin heads, which starts a new binding cycle to actin. Finally, Z-bands are pulled toward each other, shortening the sarcomere and the I-band, producing muscle fiber contraction.
Global and local climate change also makes marine ecosystems more vulnerable to lower oxygen levels (hypoxia). Aquatic organisms cannot survive without the presence of dissolved oxygen in the water.
When the climate is warmer, the surface water warms up more quickly and its density becomes lower than that of the underlying waters. However, it is the mixture of waters of different depths that helps to oxygenate the deeper waters. If the surface water is warmer and less dense, it mixes less well with the more dense bottom waters. As a result, the oxygen content will be lower in some places (deeper places for example).
At oxygen levels below 30%, species that do not tolerate hypoxic conditions must migrate to other geographic areas. If they can not migrate, their survival may be threatened.
Active transport moves small molecules against the a concentration gradient which is the opposite of diffusion or that's what i found in Quizlet
Hi!
The ancestral finch founded a new population on one of the Hawaiian Islands. Due to the founder effect , allele frequencies of the first small population on one of the islands could have differed from their continental goldfinch-like ancestors. The process of natural selection resulted in adaptation and evolution of the island population into a new species over time. Some of the birds crossed to some of the other islands where they were geographically isolated and evolved into more species occupying different niches.
In terms of population genetics, founder effect is when there is a loss of genetic diversity as a result of the establishment of a new population by a relatively few individuals. Following such an establishment, natural selection is the process which results in the genes of the fittest individuals of the population being selected over generations. This process ultimately results in evolution, and over time may give rise to new species. Geographical isolation is the physical separation of a population from another owing to geographical changes in the terrain or area. If two populations of the same species are geographically isolated, there is a great chance over time they may evolve into two different species.
Hope this helps!