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ChingLau 發問於 社會及文化語言 · 1 十年前

A few Qs

Qs 1: Why are vitamins, proteins, carbohydrates and fat so important to us?

Qs 2:What are they use for?

(Plz use Eng to answer.)

2 個解答

評分
  • 1 十年前
    最愛解答

    Vitamins are classified as either water-soluble or fat soluble. In humans there are 13 vitamins: 4 fat-soluble.

    Water-soluble

    Water-soluble vitamins dissolve easily in water, and in general, are readily excreted from the body, to the degree that urinary output is a strong predictor of vitamin consumption. Because they are not readily stored, consistent daily intake is important.

    Fat-soluble

    Fat-soluble vitamins are absorbed through the intestinal tract with the help of lipids. Because they are more likely to accumulate in the body, they are more likely to lead to hypervitaminosis than are water-soluble vitamins. Fat-soluble vitamin regulation is of particular significance in cystic fibrosis.

    Proteins are organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the genetic code specifies 20 standard amino acids, however in certain organisms the genetic code can include selenocysteine – and in certain archaea – pyrrolysine. Shortly after or even during synthesis, the residues in a protein are often chemically modified by post-translational modification, which alter the physical and chemical properties, folding, stability, activity, and ultimately, the function of the proteins.

    Carbohydrates or saccharides are the most abundant of the four major classes of biomolecules. They fill numerous roles in living things, such as the storage and transport of energy and structural components.

    Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. Chemically, fats are generally triesters of glycerol and fatty acids. Fats may be either solid or liquid at normal room temperature, depending on their structure and composition.

    資料來源: http://en.wikipedia.org/
  • 匿名
    1 十年前

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    http://www.hkenglishstudy.info/

    祝您好運!

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