False
A heliocentric is when the model is
representing the sun as the center
A geocentric says the earth is at the center of the universe
Answer:
Endothermic.
Explanation:
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In this case, it is necessary to keep in mind that exothermic processes are characterized by the release of energy and the endothermic processes by the absorption of heat. In such a way, every process from solid to liquid or gas is endothermic as they require energy to separate the molecules and therefore turn out in the phase change. On the other hand, every process from gas to liquid or solid is exothermic as heat is released to rejoin the molecules and produce the phase change.
Therefore, since solid water molecules tend to be well-arranged, it is necessary to add heat to the system to produce the phase change until gas; in such a way, this process is endothermic as energy must be absorbed by the ice.
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Answer:
Alpha helixes:
- form long thin structures important for transmembrane proteins
- have a rigid spring like structure around a central axis
Beta sheets:
- Keep their shape due to hydrogen bonds between adjacent polypeptides chains
- have a flat zig zag like structure
Explanation:
Alpha helices and beta pleated sheets are two types of secondary structure found in proteins.
Alpha helix: In this structure, the polypeptide backbone is tightly wound around an imaginary central axis drawn longitudinally through the center with the R groups of the amino acids protruding outward from the helical backbone. This structure looks like a spring and could either be a left-handed or right-handed helix, though the left-handed helix has not been observed in proteins. Each turn of the helix includes about 3.6 amino acid residues.
The alpha helix is stabilized by a hydrogen bond between the hydrogen atom attached to the electronegative nitrogen atom of a peptide linkage and the electronegative carbonyl oxygen atom of the fourth amino acid on the amino-terminal side of that peptide bond.
Alpha-helices due to their structure, are the most common transmembrane proteins- protein structure element that crosses biological membranes.
Beta sheets: In the beta conformation, the backbone of the polypeptide chain is extended into a zigzag structure. The zigzag polypeptide chain can be arranged side by side to form a structure resembling a series of pleats known as beta sheets. Hydrogen bonds formed between adjacent segments of the polypeptide chain functions to stabilize the structure.
The beta comformation in the form of turns is common in globular proteins.