Answer:
Voltage-gated Ca2+ channels
Explanation:
Modulation of Ca+2 channel Epinephrine also causes an increase in cAMP that stimulates PKA that is protein kinase A, which in turn phosphorylates the voltage-gated Ca+2 channel that is the L channel. This phosphorylation results in a protein conformational change that enchances the channels activity.
According to the research, the correct option is control. Experiments are carried out to test a hypothesis by changing one variable at a time and including an unchanged variable termed a <u>control</u>.
<h3>What are
Experiments?</h3>
It is the process by which one or more variables are intentionally manipulated by carrying out actions aimed at discovering or verifying certain phenomena.
In this sense, its basis is in the manipulation of the variables that are considered relevant, the control of strange variables and the randomization of the rest.
Therefore, we can conclude that according to the research, the correct option is control. Experiments are carried out to test a hypothesis by changing one variable at a time and including an unchanged variable termed a <u>control</u>.
Learn more about Experiments here: brainly.com/question/27750242
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Answer:
Actin filaments return to their original positions (does not occur in muscle contraction, according to the sliding filament model).
Explanation:
Answer:
1- Option A) describes an index fossil. Trilobite existed for a short time, but was abundant and lived in many locations.
2- Option B) Continents were once joined and have since drifted apart.
Explanation:
1) Fossils are animal and vegetable rests found in different strata of sedimentary rocks. Sedimentary layers deposit chronologically, so they are used to reflect history. They keep in each layer some of the forms of life that inhabited that area in the past. These fossils turn to be very useful while dating ages. The term Index fossils refer to those fossils that only existed in a given era or geological period during evolution.
Index fossils must:
• Be easily recognizable and distinguishable from all the other fossils
• Have lived in a relatively short geological period
• Present a wide geographic distribution
• Have lived in different sedimentary basins
• Appear in different types of rocks
• Be abundant
<em>A) Trilobite existed for a short time, but was abundant and lived in many locations. </em>The species accomplish the requirements. It is easily recognizable, had a wide geographic distribution, was abundant, and lived for a short time.
2) The tectonic plates theory states that there is a continual movement of the crust. It explains the movement of the different plates and their directions and interactions. The continental drift theory explains how these movements have been taking place since millions of years ago. When continents were together in a unique continent, many species used to inhabit it. When plates started to separate, they took some of these species that got apart by the ocean. Some species were already dead and fossilized, while some other organisms died during continental drift and got fossilized after the divergence. <em>The existence of the same fossils, placed in the same layers and of the same age, suggests that they used to inhabit the same area and died during the same time, meaning that continents were together when they got fossilized. </em>
Answer:
For both actin and microtubule polymerization, nucleotide hydrolysis is important for decreasing the binding strength between subunits on filaments.
Explanation:
Cytoskeletal filaments are common to eucaryotic cells and are impotartant to the spatial organization of cells. Intermediate filaments provide mechanical strength and resistance to shear stress. Microtubules determine the positions of membrane-enclosed organelles and direct intracellular transport. Actin filaments determine the shape of the cell's surface and are necessary for whole-cell locomotion. A large number of accessory proteins are present that link the filaments to other cell components, as well as to each other. Accessory proteins are essential for the assembly of the cytoskeletal filaments in particular locations, and it includes the motor proteins that either move organelles along the filaments or move the filaments themselves.
Actin filaments and microtubules are assembled with expenditure of energy i.e the ATP/GTP tightly bound to actin/tubulin is irreversibly hydrolyzed to ADP/GTP during the assembly process, and liberation of Pi in the medium occurs subsequent to the incorporation of subunits in the polymer. Pi release acts as a switch, causing the destabilization of protein-protein interactions in the polymer, therefore regulating the dynamics of these fibres. The progress is made in four areas: the chemistry of the NTPase reaction; the structure of the intermediates in nucleotide hydrolysis and the nature of the conformational switch; the regulation of parameters involved in dynamic instability of microtubules; and the possible involvement of nucleotide hydrolysis in the macroscopic organization of these polymers in highly concentrated solutions, compared with the simple case of a equilibrium polymers.
