Assume a hypothetical organism in which DNA replication is conservative. Design an experiment similar to that of Taylor, Woods, and Hughes that will unequivocally establish this fact. Using the format established in Figure 11.5, draw sister chromatids and illustrate the expected results establishing this mode of replication.

Verified step by step guidance

1. Start by understanding the concept of conservative DNA replication. In conservative replication, the original DNA molecule remains intact, and a completely new copy is made. This means after replication, one DNA molecule is entirely old, and the other is entirely new.
2. Design an experiment similar to the Taylor, Woods, and Hughes experiment, which used radioactive labeling to track DNA replication. In their experiment, they used tritiated thymidine to label newly synthesized DNA strands.
3. In your experiment, grow cells of the hypothetical organism in a medium containing a heavy isotope of nitrogen, such as 15N, to label the original DNA strands. Then, transfer the cells to a medium containing a light isotope, 14N, for one round of replication.
4. After one round of replication, isolate the DNA and use density gradient centrifugation to separate the DNA based on its density. In conservative replication, you would expect to see two distinct bands: one corresponding to the original heavy DNA and one to the newly synthesized light DNA.
5. Illustrate the expected results by drawing sister chromatids. In conservative replication, after one round of replication, one chromatid will be entirely labeled with the heavy isotope (15N), and the other will be entirely labeled with the light isotope (14N).

Key Concepts

Conservative DNA Replication

Conservative DNA replication is a theoretical model where the original DNA molecule remains intact, and an entirely new copy is synthesized. This contrasts with semi-conservative replication, where each new DNA molecule consists of one original and one newly synthesized strand. Understanding this model is crucial for designing experiments to test replication mechanisms.

Experimental Design in Genetics

Experimental design in genetics involves creating a controlled experiment to test hypotheses about genetic processes. In the context of DNA replication, this includes selecting appropriate organisms, methods for labeling DNA, and techniques for analyzing the results. A well-structured experiment can provide clear evidence supporting or refuting a specific replication model.

Sister Chromatids and Chromosome Structure

Sister chromatids are identical copies of a chromosome that are connected at a region called the centromere. During cell division, these chromatids separate to ensure each daughter cell receives an identical set of chromosomes. Illustrating sister chromatids is essential for visualizing the outcomes of DNA replication experiments and understanding how different replication models affect chromosome structure.