Hi I need help with two Molecular Biology Questions 1. Bacteria are protected fr
ID: 54784 • Letter: H
Question
Hi I need help with two Molecular Biology Questions
1. Bacteria are protected from increases in osmotic pressure by their cell walls. A major structural component of the cell wall responsible for its protective properties is the polysaccharide peptidoglycan. Which of the following best explains the rigidity and strength of the bacterial cell wall (choose all that apply)?
A) Peptidoglycan forms linear, parallel strands
B) Neighboring peptidoglycan strands are linked by peptide bonds
C) Peptidoglycan forms a highly branched structure due to its alpha 1,6 glycosidic linkages.
D) The glycosidic linkages between the monosaccharide building blocks in peptidoglycan are extraordinarily strong.
E) The polysaccharides in peptidoglycan form helical structures, as in cellulose.
2. Pure cellulose from the seed threads of cotton is tough, fibrous, and completely insoluble in water. In contrast, glycogen from muscle or liver disperses readily in hot water to make a turbid solution. Although markedly different in physical properties, both substance are composed of (1-> 4) linked D-glucose polymers of comparable molecular weight. Which of the features below are responsible for the difference in physical properties of these glucose polymers (choose all that apply)?
A) Glycogen also has (1-> 6) linkages
B) The glycosidic linkages in cellulose are beta linkages which result in the formation of extended linear strands
C) Glucose monomers in glycogen are linked by alpha linkages which cause a bend in the chain and prevent formation of long fibers
D) Parallel cellulose fibers are linked by hydrogen bonds, creating tightly associated durable fibers.
E) Many of glycogen’s hydroxyl groups are exposed to water
Explanation / Answer
1. The answer for the question are:
a. Peptidoglycan forms linear, parallel strands.
b. Neighboring peptidoglycan strands are linked by peptide bonds.
c. The glycosidic linkages between the monosaccharide building blocks in peptidoglycan are extraordinarily strong.
2. The answers for this question are:
a. Glycogen also has (1-> 6) linkages
b. Glucose monomers in glycogen are linked by alpha linkages which cause a bend in the chain and prevent the formation of long fibers
c. Parallel cellulose fibers are linked by hydrogen bonds, creating tightly associated durable fibers.