DNA Structure And Function: The Role Of Complementary Base Pairing

DNA Structure And Function: The Role Of Complementary Base Pairing

Question 1. Structures & functions of mRNA
Answer:

Structure:

• mRNA is capped at the 5′- terminal end by 7-methylguanosine triphosphate
• This helps to prevent the hydrolysis of mRNA by 5′-exonucleases
• The 3-terminal end of mRNA contains a polymer of adenylate residues known as polypeptide A tail
• This provides stability to mRNA
• mRNA contains certain modified bases such as 6-methyl adenylate in the internal structure

Functions:

• Carries genetic code from DNA to ribosomes

Question 2. Base pairing & its importance for the function & structure of DNA
Answer:

• Base pairing in DNA structure occurs between purine & pyrimidine
• If two purines face each other, they would not fit into allowable spaces
• Two pyrimidines would be too far for hydrogen bonds
  Thus, base pairing in DNA structure occurs only between purines & pyrimidines
• It occurs between
  1. Adenine and thymine or uracil
     • Two hydrogen bonds occur between them
  2. Guanine and cytosine
     • Three hydrogen bonds occur between them