Assertion (A) Glycine must be taken through diet. Reason (R) It is an essential amino acid.
Assertion (A) In presence of enzyme, substrate molecule can be attacked by the reagent effectively.
Reason (R) Active sites of enzymes hold the substrate molecule in a suitable position.
Write the reactions of D-glucose which can't be explained by its open chain structure. How can cyclic structure of glucose explain these reactions?
Chemical reactions of D-glucose which can't be explained by its open chain structure are
(i) Glucose does not give Schiff's test and does not produce hydrogensulphite addition product with $\mathrm{NaHSO}_3$, despite having aldehyde group
(ii) The pentaacetate of glucose does not react with hydroxylamine.
In actual, glucose exist in two different crystalline form $\alpha$ form and $\beta$ form. It was proposed that one of the OH groups may add to the - CHO group and form cyclic hemiacetal structure. Glucose forms a 6 membered pyranose structure.
Cyclic structure exist in equilibrium with open structure and can be represented as
Due to formation of cyclic structure of glucose CHO group of glucose remain no longer free due to which they do not show above given reactions.
On the basis of which evidences D-glucose was assigned the following structure?
Evidences on the basis of which glucose was assigned the following structure are as follows
(i) Glucose on reaction with HI produces $n$ hexane which indicates presence of six carbon atom linked in a having straight chain.
$$\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6 \xrightarrow{\mathrm{HI}} n \text { hexane }$$
(ii) Glucose on reaction with acetic anhydride produces glucose penta acetate which indicates presence of five OH groups.
$$\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6 \xrightarrow{\mathrm{Ac}_2 \mathrm{O}} \text { Glucose pentaacetate }$$
(iii) Glucose on oxidation with bromine water produces gluconic acid indicates presence of $-$CHO group.
$$\text { Glucose } \xrightarrow{\mathrm{Br}_2 / \mathrm{H}_2 \mathrm{O}} \text { Gluconic acid }$$
(iv) Glucose on reaction with $\mathrm{HNO}_3$ produces saccharic acid which indicates presence of one primary OH group.
Carbohydrates are essential for life in both plants and animals. Name the carbohydrates that are used as storage molecules in plants and animals, also name the carbohydrate which is present in wood or in the fibre of cotton cloth.
Carbohydrates that are used as storage molecules in plants and animals are as follows
(i) Plant contains mainly starch, cellulose, sucrose etc.
(ii) Animal contain glycogen in their body. So, glycogen is also known as animal starch. Glycogen is present in liver, muscles and brain when body needs glucose, enzyme breaks glycogen down to glucose.
(iii) Cellulose is present in wood, and fibre of clothes.