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  • Protein are made from long chains of amino acids.

  • Amino acids all have a similar structure, with carboxyl

  • and amino functional groups. What makes each amino acid

  • unique, is the presence of a variable, or R group.

  • The R group gives each amino acid its chemical properties.

  • Amino acids are linked together by peptide bonds, forming long

  • polypeptide chains. As these chains form,

  • the polypeptide develops multiple levels of structure, which contributes to its

  • overall shape.

  • These levels are called the primary, secondary, tertiary

  • and quaternary structures.

  • The primary structure is the order of amino acids in the polypeptide

  • chain. Amino acids can be likened to letters in the alphabet,

  • Just as thousands of words can be constructed by varying

  • the 26 letters in our alphabet, so too

  • can different proteins be created by varying the number and sequence of just

  • 20 amino acids.

  • The secondary structure refers to the pleated sheet or helix

  • that a protein chain can form due to hydrogen bonding and other

  • chemical attractions between the R groups of nearby amino acids.

  • The overall shape of a polypeptide is called its tertiary structure.

  • This level of structure is created when the secondary structure folds

  • and twists upon itself. The tertiary structure is

  • held in place by a variety of bonds and interactions that form between the R groups

  • of the amino acids on the chain. Once polypeptides

  • have formed a tertiary structure, they are commonly referred to as proteins.

  • In some cases, proteins can form

  • quaternary structures, which consist of interactions between multiple proteins.

  • These interactions often result in the formation of

  • large protein complexes. Examples of proteins that have

  • quaternary structures are hemoglobin and the sodium channels in the cell

  • membranes.

Protein are made from long chains of amino acids.

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A2 初級

タンパク質 (Proteins)

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    Yrchinese に公開 2021 年 01 月 14 日
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