Nucleotides And Nucleic Acids

Question 1

What is gene?

Answer 1

A segment of DNA molecule that contains the information required for the synthesis of a functional biological product, whether protein or RNA is referred to as gene

Question 2

What is nucleoside?

Answer 2

Nucleotide without the phosphate group is called nucleoside.

Question 3

What is a nucleic acid?

Answer 3

Nucleic acid is a polymer of nucleotides, joined by phosphodiester linkages between 5’-OH grp of one pentose and 3’-OH grp of the next.

Question 6

Function of DNA?

Answer 6

Storage and transmission of biological information

Question 7

Different types of RNA?

Answer 7

1. Ribosomal RNA (rRNA)- Components of ribosomes, the complexes that carry out the synthesis of proteins.
2. Messengers RNA (mRNA)- Intermediaries carrying genetic information from one or few genes to a ribosome, where the corresponding proteins can be synthesized.
3. Transfer RNA (tRNA)- Adaptor molecules that faithfully translate information in mRNA into specific sequence of amino acids

Question 8

Which of the purines and pyrimidines are present in DNA?

Answer 8

DNA contains 2 major purines and 2 major pyrimidines

1. Adenine and Guanine (purines)
2. Cytosine and thymine (pyrimidines)

Question 9

Which of the purines and pyrimidines are present in RNA?

Answer 9

RNA contains the following

1. Adenine and Guanine (purines)
2. Cytosine and Uracil (pyrimidines)

Question 10

Pentose in DNA?

Answer 10

2’ Deoxy-D-ribose

Question 11

Pentose in RNA ?

Answer 11

D-Ribose

Question 12

Which bond links successive nucleotides in nucleic acids like DNA or RNA?

Answer 12

Phosphodiester bond

Question 13

DNA was first isolated and characterized by which scientist?

Answer 13

Friedrich Miescher in 1868

Question 14

State the Chargaff’s rules

Answer 14

1. Base composition of DNA generally varies from species to species.
2. DNA specimens isolated from different tissues of the same species have the same composition.
3. Base composition of DNA in a given species does not change with organism’s age, nutritional state or changing environment.
4. In all cellular DNA, the number of A residues is equal to the number of T residues (A=T) and similarly G=C. From this relationship, it follows that sum of purine residues equals the sum of pyrimidine residues (A + G =T + C)

Question 15

State the type of bond present between bases of 2 complementary strands

Answer 15

Hydrogen bond

Eg A pairs with T or U, C pairs with G

Question 16

Basic components in nucleotides

Answer 16

1. Nitrogenous base - derivatives of purine and pyrimidine
2. Pentose sugar - deoxyribose or ribose
3. Phosphate group