Which of the following contributes to the double helical structure of DNA ?
Hydrogen bond
Covalent bond
Disulphide bond
van der Waals' force
A.
Hydrogen bond
According to double helical model of DNA (proposed by Watson and Crick), DNA molecule contains two deoxyribonuclide chains which are spirally coiled around each other on a common axis. These two chains are held together by the formation of hydrogen bonds,
Assertion : Glycosides are hydrolysed in acidic conditions.
Reason : Glycosides are acetals.
If both assertion and reason are true and the reason is the correct explanation of the assertion.
If both assertion and reason are true and the reason is not the correct explanation of the assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Assertion : Activity of an enzyme is pH dependent.
Reason : Change in pH affects the solubility of the enzyme in water.
If both assertion and reason are true and the reason is the correct explanation of the assertion.
If both assertion and reason are true and the reason is not the correct explanation of the assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Assertion: DNA molecules and RNA molecules are found in the nucleus of a cell.
Reason: On heating, the enzymes do not lose their specific activity.
If both assertion and reason are true and reason is a correct explanation of the assertion.
If both the assertion and reason are true but the reason is not a correct explanation of the assertion.
If the assertion is true but the reason is false.
If both the assertion and reason are false.
The number of amino acids and number of peptide bonds in a linear tetrapeptide (made of different amino acids) are respectively
4 and 4
5 and 5
5 and 4
4 and 3
In DNA, the consecutive deoxynucleotides are connected via
phosphodiester linkage
phosphomonoester linkage
phosphotriester linkage
amide linkage
In aqueous solution glucose remains as:
only in the open-chain form
only in the pyranose form
only in furanose form
in all three forms in equilibrium
