Answer and Explanation:
In rest, attraction strengths between myosin and actin filaments are inhibited by the tropomyosin. When the muscle fiber membrane depolarizes, the action potential caused by this depolarization enters the t-tubules depolarizing the inner portion of the muscle fiber. This activates calcium channels in the T tubules membrane and releases calcium into the sarcolemma. At this point, tropomyosin is obstructing binding sites for myosin on the thin filament. When calcium binds to the troponin C, the troponin T alters the tropomyosin by moving it and then unblocks the binding sites. Myosin heads bind to the uncovered actin-binding sites forming cross-bridges, and while doing it ATP is transformed 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. Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.
- Energy Production (providing energy)
- Energy Storage
- Breakdown of fatty acids
- Building Macromolecues
Answer: Amino acids combine to make proteins.
Explanation:
Minerals which are good conductors of electricity are described below.
Explanation:
- metals tend to be highly efficient conductors of heat and electricity. The vast majority of elements on the periodic table are metals, and most of these fall into one of five families: alkali metals; alkaline earth metals; the very large transition metals family; and the inner transition metal families, known as the lanthanides and actinides.
- Metals are lustrous or shiny in appearance, and malleable or ductile, meaning that they can be molded into different shapes without breaking. Despite their ductility, metals are extremely durable and have high melting and boiling points. They are excellent conductors of heat and electricity, and tend to form positive ions by losing electrons.
Answer:
A and F are phosphate groups.
B and E are sugars.
C and D are nitrogenous bases.
Explanation:
Nucleotides are the molecules responsible for composing DNA and RNA. They are formed by three units: a phosphate group, a sugar molecule and a nitrogenous base.
The sugar molecule is a pentose, which means that it is a molecule formed by 5 carbons. These collections are represented by geometrical figures such as the letters "B" and "E" shown in the figure above, where each tip represents a carbon.
The nitrogenous bases are molecules that are named adenine (A) and guanine (G) and the pyrimidine bases cytosine (C), uracil (U) and thymine (T).
The phosphate group, in turn, is a molecule derived from phosphoric acid and is the only one that does not vary in each nucleotide.