- Which three components make up a DNA nucleotide?
- Are any of these components charged (+/-)? Are any polar? Π
Each nucleotide is made up of a nitrogenous base, a pentose sugar (deoxyribose), and a phosphate
The Correct Answer and Explanation is :
A DNA nucleotide consists of three components:
- Nitrogenous base: This is the molecule that contains the genetic code. There are four types of nitrogenous bases in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G). These bases form complementary pairs—adenine pairs with thymine, and cytosine pairs with guanine—through hydrogen bonding, which helps maintain the structure of the DNA double helix.
- Pentose sugar: The sugar in DNA is deoxyribose, which is a five-carbon sugar. The “deoxy-” part refers to the fact that this sugar is missing one oxygen atom compared to ribose, the sugar found in RNA. The sugar forms part of the backbone of the DNA structure, linking the nitrogenous bases and phosphate groups together.
- Phosphate group: The phosphate group consists of a phosphorus atom bound to four oxygen atoms. It is negatively charged due to the presence of the oxygen atoms, which makes it an important component in maintaining the negative charge of DNA and the overall stability of the molecule.
Charge and Polarity:
- The phosphate group is negatively charged (due to the oxygen atoms) and contributes to the overall negative charge of DNA.
- The nitrogenous bases themselves are not charged, but they are polar due to the presence of nitrogen and oxygen atoms, which can form hydrogen bonds. This polarity plays a role in the base-pairing interactions that stabilize the DNA structure.
- The pentose sugar (deoxyribose) is not charged, but it is polar due to the hydroxyl (-OH) groups attached to the carbons, which can form hydrogen bonds with water or other polar molecules.
In summary:
- The phosphate group is negatively charged.
- The nitrogenous bases are polar, but not charged.
- The pentose sugar is polar due to its hydroxyl groups, but not charged.