What is the difference between a nucleoside and a nucleotide?
A nucleoside contains only two basic components of nucleic acids i.e., a pentose sugar and a nitrogenous base. It is formed when 1- position of pyrimidine (cytosine, thiamine or uracil) or 9-position of purine (guanine or adenine) base is attached to C -1 of sugar (ribose or deoxyribose) by a β-linkage. Nucleic acids are also called polynucleotides since the repeating structural unit of nucleic acids is a nucleotide.
A nucleotide contains all the three basic . components of nucleic acids, i.e., a phosphoric acid group, a pentose sugar and a nitrogenous base. These are obtained by esterification of C5, – OH group of the pentose sugar by phosphoric acid.
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.
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?
Which of the following terms are correct about enzyme?
(a) Proteins (b) Dinucleotides
(c) Nucleic acids (d) Biocatalysts
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 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.
Aldopentoses named ribose and 2-deoxyribose are found in nucleic acids.
What is their relative configuration?
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
How do you explain the presence of all six carbon atoms in glucose in a straight chain?
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?
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.
Sucrose is dextrorotatory but the mixture obtained after hydrolysis is laevorotatory. Explain.
Assertion (A): All naturally occurring a-amino acids except glycine are optically active.
Reason (R): Most naturally occurring amino acids have L-configuration.
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?
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.
How are vitamins classified? Name the vitamin responsible for the coagulation of blood.
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.
In disaccharides, if the reducing groups of monosaccharides, i.e., aldehydic or ketonic groups are bonded, these are non-reducing sugars. Which of the following disaccharide is a non-reducing sugar?
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.
Which of the following carbohydrates are branched polymer of glucose?
(a) Amylose (b) Amylopectin (c) Cellulose (d) Glycogen
Amino acids are classified as acidic, basis or neutral depending upon the relative number of amino and carboxyl groups in their molecule. Which of the following are acidic?
Which of the following are purine bases?
(a) Guanine (b) Adenine (c) Thymine (d) Uracil
Match the following enzyme given in Column I with the reactions they catalyse given in Column II.
