DNA with only pyrimidine bases would have a uniform width along the double helix, as pyrimidine bases (cytosine and thymine) are smaller than purine bases (adenine and guanine). This would result in a more consistent appearance compared to DNA with a mix of purine and pyrimidine bases. The structure would still maintain the characteristic double helix shape, with the pyrimidine bases forming hydrogen bonds with their complementary purine bases. Overall, the DNA would appear more uniform and consistent in its structure with only pyrimidine bases. **

Purine bases are larger, double-ringed molecules, while pyrimidine bases are smaller, single-ringed molecules. Purine bases include adenine and guanine, while pyrimidine bases include cytosine, thymine (in DNA), and uracil (in RNA). Additionally, purine bases always pair with pyrimidine bases in DNA and RNA, forming the complementary base pairs that make up the genetic code. This pairing is essential for the structure and function of DNA and RNA molecules. **

Purine and pyrimidine are two types of nitrogenous bases found in DNA and RNA. The main difference between them is their chemical structure. Purine bases, such as adenine and guanine, have a double-ring structure, while pyrimidine bases, such as cytosine, thymine, and uracil, have a single-ring structure. Additionally, purine bases always pair with pyrimidine bases in DNA and RNA, forming the complementary base pairs that are essential for the structure and function of nucleic acids. **

Contemporary plays can be considered modern in the sense that they reflect current societal issues, values, and cultural norms. They often incorporate modern technology, language, and themes that are relevant to today's audience. However, the term "modern" can also refer to a specific historical period in theater, typically the late 19th and early 20th centuries, so in that sense, contemporary plays may not be considered modern. Overall, the classification of contemporary plays as modern depends on the context and definition being used. **

The substitution of Cl by NH2 on the pyrimidine occurs through the same mechanism because both the chlorine (Cl) and the amino group (NH2) are nucleophiles, meaning they both have a pair of electrons available for bonding. This allows them to undergo similar nucleophilic substitution reactions. Additionally, the pyrimidine ring structure provides a similar electronic environment for both substitutions, leading to the same mechanism for the substitution reaction. Therefore, the substitution of Cl by NH2 on the pyrimidine occurs through the same mechanism due to the similar reactivity of the nucleophiles and the electronic environment of the pyrimidine ring. **

Before the specific base pairs in DNA were known, the pyrimidine and purine bases were detected through chemical and physical methods. For example, the bases were isolated and purified from DNA samples and then analyzed using techniques such as chromatography and spectrophotometry. Additionally, researchers used X-ray crystallography to study the structure of DNA and infer the presence of the bases. These methods allowed scientists to identify the presence of pyrimidine and purine bases in DNA before the specific base pairs were determined. **

Modern drama typically refers to the drama that was written and produced between the late 19th and early 20th centuries, while contemporary drama refers to drama that is being written and produced in the present day. Modern drama often reflects the social and political issues of the time in which it was written, while contemporary drama reflects the current issues and concerns of today's society. Additionally, modern drama may be more focused on traditional theatrical forms and structures, while contemporary drama may experiment with new forms and styles. **

Yes, flexibility is important for Modern Dance Contemporary. Many movements in this style require a wide range of motion and flexibility in the joints. Being flexible can help dancers execute movements with more ease and fluidity, allowing them to fully express themselves through their dancing. Regular stretching and conditioning exercises can help improve flexibility and enhance performance in Modern Dance Contemporary. **