Question

The segment of molecules which codes or specific for one polypeptide chain is called as \\_\\_\\_\\_\\_.
$A.$ Gene
$B.$ Pentose
$C.$ Phosphate unit
$D.$ Amino acid

Answer 1

Deoxyribonucleic acid $\left( {DNA} \right)$ is molecules containing two polypeptide chains that coil around each other to form a double helix. Most $\left( {DNA} \right)$ is located in the cell nucleus (where it is called nuclear $DNA$ , but a small amount of $DNA$ also found in mitochondria (where It is called mitochondrial $DNA$ or $mtDNA$ .

Complete step by step answer:
Information in $DNA$ is stored as code made up of four chemical bases namely, Adenine, Guanine, Cytosine, and Thymine. They are held by hydrogen bond Adenine Thymine or Guanine and Cytosine. There are about $3$ million bases in human $DNA$
Gene: The segment of $DNA$ molecules which codes or is specific for one polypeptide chain is called a gene. It is the physical and functional unit of heredity. A gene is a functional segment of $DNA$ that provides the genetic information necessary to build a protein. Each gene provides the code necessary to construct a particular protein.
Pentose: A pentose is a monosaccharide with five carbon atoms. The pentose sugar in $DNA$ is called deoxyribose and in $RNA$ , the sugar is ribose. The main functions of pentose sugar ribose and deoxyribose are part of the nucleotide that make up the crucial nucleic acid like $DNA$ and $RNA$ .
Phosphate unit: Chemical formula of phosphate is $PO_4^{3 - }$ . It consists of one phosphorus and four oxygen atoms. It is found in $DNA$ and $RNA$ also in molecules such as Adenosine triphosphate $\left( {ATP} \right)$ , which provide energy to cells.
Amino acid: Amino acid is the monomers that make up protein. They join together to form a short polymer chain called peptide or a longer chain called polypeptide.

Thus option $A$ is correct.

Note:
Gene is mainly responsible for information stored in $DNA$ in the form of code. The main function of $DNA$ is to encode the sequence of amino acid residues in proteins, using the genetic code. $DNA$ is also responsible for replication.