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Agata [3.3K]
3 years ago
9

The first sphincter encountered in the alimentary canal is the: The first sphincter encountered in the alimentary canal is the:

pyloric sphincter. ileocecal sphincter. gastroesophageal sphincter. upper esophageal sphincter.
Biology
1 answer:
Arte-miy333 [17]3 years ago
4 0

Answer:

The correct answer is: upper esophageal sphincter.

Explanation:

The alimentary canal is a very long tract responsible for the digestion of the food. It is composed of several organs with many different and important functions. The alimentary canal also has a few sphincters, which are muscular valves that open and close when needed for the food to pass or be retained.

The first sphincter is the upper esophageal sphincter. One particularity of this sphincter is that is one of the few sphincters in the body that opens and closes under our conscious control, which happens when we decide to swallow our food.

From the first to the last, the order of the sphincters in the gastrointestinal tract is: upper esophageal sphincter, lower esophageal sphincter or gastroesophageal sphincter, pyloric sphincter, ileocecal sphincter, and anus.

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Explain the relationship between polypeptides and proteins .
Hatshy [7]

Peptide bonds, and proteins. Amino acids are the monomer building blocks of proteins. When two are joined together in a peptide bond, they form proteins.A polypeptide is amino acids that bond to each other one at a time to form a long chain held together by peptidebonds

.Polypeptides and proteins are natural and essential organic compounds of a cell. They are both composed of amino-acids. Amino-acids are naturally occurring compounds which link together to form peptides, polypeptides, and proteins. Each amino-acid contains one amine (-NH2) and one hydroxyl (-COOH) group, as well as a specific side chain (R group). The side chain group varies in size, shape, charge, and reactivity, and is therefore unique to each amino-acid. There are 20 types of monomeric amino-acids capable of linking together in different combinations, thus conferring polypeptides and proteins with a high diversity.

A polypeptide is a polymer with a defined sequence of amino-acids linked together through covalent peptide bonds. A peptide bond is the result of a condensation reaction between two amino-acids: the carboxyl group of one amino-acid reacts with the amino group of an adjacent amino-acid, releasing a molecule of water (H2O).  

Proteins are structurally and functionally complex molecules. The term protein is used to describe the three-dimensional structure formed by the folding of one or more polypeptides. Proteins present four levels of structural organization, with the polypeptide being the primary structure. A protein has a secondary structure when polypeptide chains form α helices and β sheets.


4 0
3 years ago
Under which circumstances should we try to control the population numbers of Pfiesteria?
zvonat [6]

Answer:

Pfiesteria species generally found in estuaries, the population of which are needed to be controlled only when they becomes toxic. Presence of large of fish triggers toxicity in Pfiesteria.

Explanation:

Pfiesteria are known to be associated with fish kills as for example large fish kill in the seas of North Carolina. It also causes blooming of algae in enormous numbers thus make the water bodies, hostile for survival of fishes and other marine lives. It affects human too by release of toxins in air and water often resulting in respiratory problems, infections of gastrointestinal system, headaches and fatigue. In this type of grave circumstances, leading to outburst of population of Pfiesteria, there is an urgent need to control.

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3 years ago
Enzymatic catalysis of the peptide bond between the growing polypeptide and the next incoming amino acid takes place in which bi
Kay [80]

Answer:

A site

Explanation:

During the process of translation, ribosomes play a major role in connecting mRNA codons with tRNA anticodons. Ribosomes are composed of  two subunits which consist ofproteins and rRNA. The tree sites of ribosomes are:

  • P site or peptidyl site-this site binds to the tRNA which holds the growing polypeptide chain.
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  • E site or exit site-the site for the final binding of t-RNA .
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