Which of the following are purine bases?
(a) Guanine (b) Adenine (c) Thymine (d) Uracil
(a, b) Purines consist of six membered and five membered nitrogen containing ring fused together.
Guanine and adenine are purine bases whose structures are
While thymine and uracil are pyrimidine bases.
Hence (a) and (b) are correct choices.
The letters ' D ' or ' L' before the name of a stereoisomer of a compound indicate the correlation of configuration of that particular stereoisomer.
This refers to their relation with one of the isomers of glyceraldehydes. Predict whether the following compound has ‘D' or ‘L' configuration.
Which monosaccharide units are present in starch, cellulose and glycogen and which linkages link these units?
Assertion (A): Vitamin D can be stored in our body.
Reason (R): Vitamin D is fat soluble vitamin.
Assertion (A): Glycine must’be taken through diet.
Reason (R): It is an essential amino acid.
Which of the following terms are correct about enzyme?
(a) Proteins (b) Dinucleotides
(c) Nucleic acids (d) Biocatalysts
Carbohydrates are classified on the basis of their behaviour on hydrolysis and also as reducing or non-reducing sugar. Sucrose is a .
(a) monosaccharide (b) disaccharide
(c) reducing sugar (d) non-reducing sugar
α-Helix is a secondary structure of proteins formed by twisting of polypeptide chain into right handed screw like structures. Which type of interactions are responsible for making the a-helix structure stable?
Some enzymes are named after the reaction, where they are used. What name is given to the class of enzymes which catalyse the oxidation of one substrate with simultaneous reduction of another substrate?
When RNA is hydrolysed, there is no relationship among the quantities of different bases obtained. What does this fact suggest about the structure of RNA?
Classify the following into monosaccharides and disaccharides. Ribose, 2-deoxyribose, maltose, galactose, fructose and lactose.
Aldopentoses named ribose and 2-deoxyribose are found in nucleic acids.
What is their relative configuration?
Protein found in a biological system with a unique three dimensional structure and biological activity is called a native protein. When a protein in its native form, is subjected to a physical change like change in temperature or a chemical change like, change in pH, denaturation of protein takes place. Explain the cause.
Activation energy for the acid catalysed hydrolysis of sucrose is 6.22 kJ mol-1, while hydrolysis is catalysed by the enzyme sucrase. Explain.
Three structures are given below in which two glucose units are linked. Which of these linkages between glucose units are between C1 and C4 and which linkages are between C1 and C6?
Which of the following monosaccharides are present as five membered cyclic structure (foranose structure)?
(a) Ribose (b) Glucose (c) Fructose (d) Galactose
Assertion (A): β-glycosidic linkage is present in maltose.
Reason (R): Maltose is composed of two glucose units in which C-l of one glucose unit is linked to C-4 of another glucose unit.
What products would be formed when a nucleotide from DNA containing thymine is hydrolysed?
How do you explain the presence of all six carbon atoms in glucose in a straight chain?
Monosaccharides contain carbonyl group hence are classified, as aldose or ketose. The number of carbon atoms present in the monosaccharide molecule are also considered for classification. In which class of monosaccharide will you place fructose?
In fibrous proteins, polypeptide chains are held together by
(a) van der Waals forces (b) disulphide linkage
(c) electrostatic forces of attraction (d) hydrogen bonds
In nucleoside a base is attached at 1′ position of sugar moiety. Nucleotide is formed by linking of phosphoric acid unit to the sugar unit of nucleoside. At which position of sugar unit is the phosphoric acid linked in a nucleoside to give a nucleotide?
