Rationale
Phosphate groups are found in substantial quantities in both the cell membrane and DNA.
Phosphate groups are integral components of both DNA and the cell membrane. In DNA, phosphate groups link together the deoxyribose sugars to form the backbone of the DNA molecule. In the cell membrane, phosphate groups are part of phospholipids, the main component of the membrane, contributing to its amphipathic nature and thus its function.
A) Nitrogenous bases
Nitrogenous bases are a key component of DNA, forming the rungs of the DNA double helix. However, they are not found in substantial quantities in the cell membrane. The cell membrane is primarily composed of phospholipids, cholesterol, proteins, and carbohydrates, but not nitrogenous bases.
B) Steroids
Steroids are a type of lipid found in the cell membrane, contributing to its fluidity and stability. However, they are not a component of DNA, which is composed of phosphate groups, deoxyribose sugar, and nitrogenous bases.
C) Phosphate groups
As previously mentioned, phosphate groups are a crucial part of both the cell membrane and DNA. In the cell membrane, they form part of the phospholipids that make up the bulk of the membrane. In DNA, they serve as the link between the deoxyribose sugars of the nucleotides, forming the backbone of the DNA molecule.
D) Lipids
Lipids are a major component of the cell membrane, providing a barrier between the cell and its external environment. However, they are not found in DNA, which is composed of phosphate groups, deoxyribose sugars, and nitrogenous bases.
Conclusion
Among the given choices, only phosphate groups are found in substantial quantities in both the cell membrane and DNA. Nitrogenous bases and lipids are integral components of DNA and the cell membrane, respectively, but they are not found in both. Steroids, a type of lipid, are present in the cell membrane but not in DNA. This highlights the unique roles and distributions of these molecules in cellular structures and functions.
