Two DNA chains are held together by: Bbl6epure oAMH orger: a. phosphodiester bond b. covalent bond c. disulfide bridge d. ionic bond

## Step 1<br />The structure of DNA is a double helix, which is held together by hydrogen bonds. These bonds are formed between the nitrogenous bases of the two strands of DNA.<br /><br />## Step 2<br />The nitrogenous bases are adenine (A), thymine (T), cytosine (C), and guanine (G). Adenine always pairs with thymine, and cytosine always pairs with guanine. This pairing is due to the hydrogen bonds that form between these bases.<br /><br />## Step 3<br />The hydrogen bonds are not the only type of bond in DNA. The covalent bonds are responsible for holding the atoms within each nucleotide together. These bonds are strong and stable, ensuring the integrity of the DNA molecule.<br /><br />## Step 4<br />The phosphodiester bonds are also important in the structure of DNA. They link the sugar of one nucleotide to the phosphate of the next, forming the backbone of the DNA strand.<br /><br />## Step 5<br />The disulfide bridges are not involved in the structure of DNA. They are typically found in proteins, where they help to stabilize the protein structure.<br /><br />## Step 6<br />The ionic bonds are also not involved in the structure of DNA. They are typically found in ionic compounds, where they help to hold the ions together.