Biomolecules Test - 7

DNA has a double strand helix structure. Two nucleic acid chains are wound about each other and held together by hydrogen bonds between pairs of bases. The two strands are complementary to each other because the hydrogen bonds are formed between specific pairs of bases. In secondary structure of RNA, helices are present which are only single stranded. Sometimes they fold back on themselves to form a double helix structure.

Those amino acids which cannot be synthesised in the body and must be obtained through diet, are known as essential amino acids. Proline is not an essential amino acid.

Cellulose occurs exclusively in plants and it is the most abundant organic substance in plant kingdom. It is a predominant constituent of cell wall of plant cells. Cellulose cannot be hydrolysed in human digestive system because the enzymes required to digest it are not present in human body.

Deficiency of Vitamin B₂ (Riboflavin) results in Cheilosis (fissuring at corners of mouth and lips).

Information regarding the sequence of nucleotides in the chain of a nucleic acid is called its primary structure. This gives information about sequence of bases in DNA which is primarily responsible for the hereditary character. Thus nucleotides are carrier of hereditary character.

Proteins are the polymers of α-amino acids. So building unit of a protein is α – Aminoacid.

In proteins α-amino acids are connected to each other by peptide bond or peptide linkage. Chemically, peptide linkage is an amide formed between –COOH group and –NH₂ group. The reaction between two molecules of similar or different amino acids, proceeds through the combination of the amino group of one molecule with the carboxyl group of the other. This results in the elimination of a water molecule and formation of a peptide bond –CO–NH–. So protein is condensation polymer.

If adrenal cortex does not function properly then one of the results may be Addison’s disease characterised by hypoglycemia, weakness and increased susceptibility to stress.

The combination of ovum and sperm forms the fertilized egg which further gets implanted in the uterus. This is brought about by the hormone progesterone which prepares uterus for this process.

The role of insulin is to keep the blood glucose level within the narrow limit. Insulin is released in response to the rapid rise in blood glucose level. On the other hand hormone glucagon tends to increase the glucose level in the blood.  The two hormones together regulate the glucose level in the blood.