The two strands in DNA are not identical but are complementary. Explain.
he two strands in DNA molecule are held together by hydrogen bonds between purine base of one strand and pyrimidine base of the other and vice versa. Because of different sizes and geometries of the bases, the only possible pairing in DNA are G (guanine) and C (cytosine) through three H-bonds, (i.e.,C = G) and between A (adenine) and T (thiamine) through two H-bonds (i.e., A = T). Due to this base -pairing principle, the sequence of bases in one strand automatically fixes the sequence of bases in the other strand. Thus, the two strands are complimentary and not identical.
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?
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?
Assertion (A): Deoxyribose, C5H10O4 is not a carbohydrate.
Reason (R): Carbohydrates are hydrates of carbon so compounds which follow Cx(H2O)y formula are carbohydrates.
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
Aldopentoses named ribose and 2-deoxyribose are found in nucleic acids.
What is their relative configuration?
Assertion (A): Vitamin D can be stored in our body.
Reason (R): Vitamin D is fat soluble vitamin.
How do you explain the presence of all six carbon atoms in glucose in a straight chain?
Sucrose is dextrorotatory but the mixture obtained after hydrolysis is laevorotatory. 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 carbohydrates are branched polymer of glucose?
(a) Amylose (b) Amylopectin (c) Cellulose (d) Glycogen
Activation energy for the acid catalysed hydrolysis of sucrose is 6.22 kJ mol-1, while hydrolysis is catalysed by the enzyme sucrase. Explain.
Match the vitamins given in Column I with the deficiency disease they cause given in Column II.
Assertion (A): All naturally occurring a-amino acids except glycine are optically active.
Reason (R): Most naturally occurring amino acids have L-configuration.
Which of the following monosaccharides are present as five membered cyclic structure (foranose structure)?
(a) Ribose (b) Glucose (c) Fructose (d) Galactose
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?
Assertion (A): Glycine must’be taken through diet.
Reason (R): It is an essential amino acid.
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?
Structures of glycine and alanine are given below. Show the peptide linkage in glycylalanine.
Match the following enzyme given in Column I with the reactions they catalyse given in Column II.
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.
Glucose or sucrose are soluble in water but cyclohexane and benzene (simple six membred ring compounds) are insoluble in water Explain.
What products would be formed when a nucleotide from DNA containing thymine is hydrolysed?
