05 DNA - The Genetic Material

The 3' oxygen of deoxyribose of a DNA nucleotide is linked to the 5' oxygen of deoxyribose of the adjacent nucleotide by way of a phosphate group.

Watson and Crick used the X-ray diffraction data of Wilkins and Franklin.

The DNA molecule consists of two strands that are held together by a backbone. This backbone is made up of alternating deoxyribose sugar molecules and phosphate groups. The phosphate group, which is represented by the chemical formula PO4, forms the "backbone" of the DNA molecule. It provides stability and structure to the DNA molecule, allowing it to maintain its double helix shape. Therefore, the correct answer is phosphate, represented by PO4.

The pyrimidines found in DNA are cytosine and thymine. Thymine is one of the four nucleotide bases that make up DNA, along with adenine, guanine, and cytosine. These bases pair up with each other in a specific way, with adenine always pairing with thymine. Thymine plays a crucial role in the structure and function of DNA, as it forms hydrogen bonds with adenine to create the double helix structure of the DNA molecule. Therefore, thymine is a vital component of DNA and is always found alongside cytosine in the DNA molecule.

The percentage of guanine in DNA is always equal to the percentage of cytosine. Since adenine and thymine always pair up in DNA, the total percentage of adenine and thymine is 50%. Therefore, the percentage of guanine and cytosine combined is also 50%. If the percentage of adenine is 23%, then the percentage of guanine is also 23%.

Avery, MacLeod, and McCarty showed that DNA (deoxyribonucleic acid) of IIIS bacteria was capable of transforming live IIR bacteria into live IIIS bacteria.

The smaller groove on opposite sides of a DNA double helix is called the minor groove. This groove is narrower and less accessible compared to the larger groove. It plays a crucial role in DNA-protein interactions and is involved in the recognition and binding of specific proteins to the DNA molecule. The minor groove provides important structural information and contributes to the overall stability and function of the DNA molecule.

Miescher discovered nuclein, a new class of organic molecule known today as nucleic acid. He determined that it was not a protein based on the absence of the element sulfur (S) or sulphur. Proteins typically contain sulfur in their amino acid composition, whereas nucleic acids, such as DNA and RNA, do not. Therefore, the absence of sulfur in nuclein indicated that it was a different type of molecule, leading to the discovery of nucleic acids.

DNA's two strands run in opposite directions, meaning that one strand runs in the 5' to 3' direction while the other runs in the 3' to 5' direction. This arrangement is referred to as antiparallel.

The nitrogen base on the right is thymine. Thymine is one of the four nitrogenous bases found in DNA. It pairs with adenine through hydrogen bonding, forming a base pair that stabilizes the DNA double helix structure. Thymine is a pyrimidine base, meaning it has a single-ring structure. It is specifically found in DNA and is not present in RNA, where it is replaced by uracil.

A DNA double helix is composed of two strands that are twisted together. Each base pair in the helix is approximately 3.4 angstroms (Å) long. Therefore, to determine the length of a DNA double helix, we multiply the number of base pairs by 3.4. In this case, since the helix is 30 base pairs long, the length would be 30 * 3.4 = 102 Å.

In Griffith's 1928 experiment, the injection of live IIR bacteria and heat-killed IIIS bacteria resulted in the transformation of the IIR bacteria into IIIS bacteria. This transformation was observed in the mouse, indicating that some factor from the heat-killed bacteria had been transferred to the live bacteria, allowing them to gain the ability to cause disease. This result was significant as it suggested the presence of a transforming principle, later identified as DNA, which carries genetic information and can be transferred between bacteria.

Miescher discovered nuclein, which is now known as nucleic acid. He determined that it was not a protein because it contained phosphorus, which is not found in proteins. Proteins are composed of carbon, hydrogen, oxygen, and nitrogen, but the presence of phosphorus in nuclein indicated that it was a different type of organic molecule. This discovery laid the foundation for our understanding of nucleic acids and their role in genetics.