Question

Why does I3^- (note: the 3 is a subscript) bind to amylose starch but not amylopectin starch?

What do structural polysaccharides seem to have in common?

What is a peptidoglycan? Describe the types of covalent bonds that support the structure of peptidoglycans. What is the difference between the cell wall of gram + and gram – bacteria? Which type of bacteria does penicillin-like antibiotics affect and why? Why is N-acetylmuramic acid (NAM), in addition to NAG, important to bacterial cell walls?

Answer 1

Amylose forms a colloidal dispersion in hot water whereas amylopectin is completely insoluble, amylose in starch is responsible for the deep blue color in the presence of iodine.the iodine molecule slips inside of the amylose coil.

polysaccharides have carbohydrate molecules composed of long chain of monosaccharides units bound together by glycosidic linkages

peptidoglycan :- it is a substance or a mesh- like layer forms cell wall of many bacteria and able to allow sugar,amino acids ,and other ions into the cell when require

The sugar component is of NAG(N-acetylglucosamine) and NAM (N-acetylmuramic acid) consists three to five peptide chains of amino acids (N-acetylmuramic acid)

Difference between gram-negative and gram-positive bacteria :-

Gram + bacteria do not have an outer cell membrane found in gram - bacteria ,and the cell wall of gram-positive bacteria is high in peptidoglycan which is responsible for retaining crystal violet die .

penicillin affects on staphylococci and streptocci bacterial infections.

N-Acetylmuramir acid or MurnAc or NAM is important to becterial cell wall. It is a monosaccharide derivative of N-acetylglucosame also it is part of biopolymer in the bacterial cell wall,built from alternate attachment of units of N-Acetylglucosamine (GlcNAc) and N- acetylmuramic acid (MurNAc).