Question

Researchers performed an experiment to investigate DNA replication. First, they synthesized radioactively-labeled nucleotides, which are nucleotides that contain radioactive elements that allow them to be visualized. Then, they inserted the radioactively-labeled nucleotides into a cell. When the cell divided, it incorporated the radioactively-labeled nucleotides into its DNA during DNA replication.

The following image shows the cell's DNA before and after replication. The original DNA strands are shown in blue and the DNA strands with the radioactively-labeled nucleotides are shown in orange.


Which statement is best supported by the results of this experiment?

Answer 1

DNA replication is a semiconservative process.

Step-by-step explanation:

The DNA molecule is made of two chains (or two strands), also called double-stranded (two chains).

There is complementarity of nucleotides or nitrogen bases:

- Thymine with Adenine,

- Guanine with Cytosine.

This DNA molecule is duplicated. For this, locally, we have an opening of these two chains by enzymes. We speak of enzymatic complex. This set of enzymes comes to open both strands of DNA. After opening the two strands, in the nucleus, there are several free nucleotides which bind to the template strand by complementarity.

We had a single molecule of DNA, we then had two. The two chromatids (or the two DNA helices) are therefore sister, because they are strictly identical. We speak of a semi-conservative replication because we keep one of the two matrix strands to copy identically its complementary, thanks to the complementarity of nucleotides or nitrogenous bases.