Macromolecules- polypeptides, polysaccharides, nucleic acids- are important comp

Question

Macromolecules- polypeptides, polysaccharides, nucleic acids- are important components of living systems. Members of each class of macromolecules are composed of monomers joined by dehydration reactions to form polymers.

A) what is a dehydration reaction?

B) what monomers are used to construct each of the three classes of macromolecules? ( in each case, indicate the functional groups that interact to allow successive monomers to be linked together.

C) Only one of the three classes of macromolecules includes representatives that are branched? d)without referring to electrical charge, what do we mean when we say that both polypeptides and nucleic acids display polarity?

Explanation / Answer

a) Dehydration reaction involves the loss of water. When two monomers come closer to connect, a hydrogen atom from one monomer and -OH from second molecule combine to form water molecule which releases as substrate alongwith polymers.

b) There are three major types of macromolecules present in mammals

1. Carbohydrates where momoner unit is monosaccharides.

2. Nucleic acids where monomer unit is nucletides.

3. Proteins where monomer unit is amino acids.

Monosaccharides posses two functional groups, one carboxyl group and other hydroxyl group. On polymerization, hydroxyl group of one monosaccharide react with hydroxyl group of other monosaccharide and combined with glycosidic linkage.

Nucleotides comprise of three parts, Phosphate, Monosaccharide (Ribose in ribonucleotides & Deoxyribose in DNA, which lacks a 2' -OH) and a base. Nucleotides polymerizes to form esteric linkage between the 5'-phosphate of one nucleotide and the 3' -OH of other nucletide alongwith release of one molecule of water.

Amino acids contains a carboxylic acid (-COOH) group and an amino (-NH2) group. Amino acid polymerizes to form an amide linkage (peptide bond) between the amino and carboxyl groups of two different amino acids. A molecule of water is also released with polymerization of amino acids.

c) Glycoprotein, a type of protein having a carbohydrate as prosthetic group, represents the branched macromolecules.

d) Polypetides and nucletides shows polarity because of their peculiar structures. Polypeptides possess COO- at one end and NH3+ at other end which causes polarity of molecule. on the other hand, base pairing in nucleic acids form complimentary sequences which create double helix of opposite polarity.

Example :

5' ...ATCCGAGTG... 3'

3' ...TAGGCTCAC... 5'

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