//M0//QN1//CS//DL0

Carbohydrates are optically active polyhydroxy aldehydes and ketones. They are also called saccharides. All those carbohydrates which reduce Fehling’s solution and Tollen’s reagent are referred to as reducing sugars. Glucose, the most important source of energy for mammals, is obtained by the hydrolysis of starch. Vitamins are necessary food factors required in the diet. Proteins are the polymers of α-amino acids and perform various structural and dynamic functions in the organisms. Deficiency of vitamins leads to many diseases.(a) What are reducing sugars?(b) Why are carbohydrates considered optically active, and what is their structural significance?(c) What are proteins made of?(d) Why is vitamin C not stored in our body?

//X

//M0//QN2//CS//DL0//EQ

Pentoses and hexoses undergo intramolecular hemiacetal or hemiketal formation due to the combination of the hydroxyl group (-OH) with the carbonyl group. The resulting structure is either a five- or six-membered ring containing an oxygen atom. In their free state, all pentoses and hexoses exist predominantly in the pyranose form (resembling pyran). However, in the combined state, some of them exist as five-membered cyclic structures called furanose. The cyclic structure of glucose is represented by the Haworth projection. α–D–glucose and β–D–glucose differ in the configuration at the anomeric (C–1) carbon atom and are therefore called anomers. The C–1 carbon atom is referred to as the anomeric carbon. The six-membered cyclic structure of glucose is known as the pyranose structure.(a) What causes pentoses and hexoses to form cyclic structures?(b) What is the difference between pyranose and furanose structures?(c) What are anomers, and how do α and β-D-glucose differ?(d) In the structure of α-D-glucose, which carbon is the anomeric carbon?

//X

//M0//QN3//CS//DL0

When a protein in its native state is exposed to physical factors such as temperature changes or chemical factors like pH alterations, its hydrogen bonds are disrupted. As a result, the protein’s globular structure unfolds, its helix uncoils, and it loses its biological activity. This process is known as denaturation of protein. During denaturation, the secondary and tertiary structures are altered, but the primary structure remains unchanged. Examples of protein denaturation include the coagulation of egg white upon boiling, the curdling of milk, and the formation of cheese when acid is added to milk.(a) What is protein denaturation?(b) What causes denaturation of proteins?(c) Which structures of a protein are affected during denaturation?(d) Give examples of protein denaturation in daily life.

//X

//M0//QN4//CS//DL0//EQ

A medical research insitute is studying how carbohydrates, protein and enzymes behave inside human cells. To understand metabolic pathways, Scientist analyze.

//X

(a) In water, glucose interconverts between α - glucose and β - glucose.

This happens via open-chain aldehyle form, causing a change in specific rotation until equilibrium is reached.

(b) In sucrose, the anomeric carbon of glucose
(1) and fructose (2) are both involved in glycosidic bonding.

Thus, neither ring can open → no free aldehyde or keto group → cannot reduce Tollen’s or fehling’s reagent.

(c) Denaturation breaks, hydrogen bonds, hydrophobic interactions and salt bridges. So, protein losses tertiary / Secondary structure, Active site destroyed and loss of biological function.

(d)

//M0//QN5//CS//DL0

A biotechnology firm studies nucleic acids, vitamins, and amino acids to design new nutritional supplements : They analyze : Structure of DNA - RNA, Base pairing rules, essential vs non-essential amino acids, vitamin deficiencies and hydrolysis of nucleotides. Key Observations : 1. DNA contain A, T, G, C, where as RNA contain A, V, G, C 2. Adenine paires with thymine by two H-bonds; guanine pairs with cytosine by 3 H-bonas 3. Vit. C deficiency → Seurvy 4. Thiamin deficiency → beriberi 5. Hydrolysis of RNA gives a mixture of ribose, phosphate and nitrogenous bases.

//X