How Well You Know DNA Structure? Quiz

The correct answer is "Double helix" because the structure of DNA is famously known as a double helix. It consists of two strands that are twisted around each other in a spiral shape, resembling a twisted ladder or a twisted spiral staircase. This unique structure allows DNA to store and transmit genetic information.

In eukaryotic cells, DNA is indeed found in the nucleus. The nucleus is a membrane-bound organelle that houses the cell's genetic material, including DNA. This is in contrast to prokaryotic cells, where DNA is found in the cytoplasm. The presence of DNA in the nucleus of eukaryotic cells allows for more efficient regulation of gene expression and protection of the genetic material from potential damage in the cytoplasm.

The dashed lines between the two bases represent hydrogen bonds. Hydrogen bonds are weak attractions between a hydrogen atom and an electronegative atom, such as oxygen or nitrogen. In DNA, hydrogen bonds form between the nitrogenous bases of the two DNA strands, holding the strands together in a double helix structure. These hydrogen bonds are crucial for the stability and integrity of the DNA molecule.

Chargaff's rule of base pairing states that in DNA, adenine (A) always pairs with thymine (T) and cytosine (C) always pairs with guanine (G). This rule is important because it explains the complementary nature of the DNA strands and provides the basis for DNA replication and transcription. The other options in the question are incorrect because they do not accurately represent Chargaff's rule.

The diagram represents the selection of "Nucleotide". Nucleotides are the building blocks of nucleic acids, such as DNA and RNA. They consist of a nitrogenous base (either a purine or a pyrimidine), a sugar molecule (in this case, deoxyribose), and a phosphate group. The diagram includes all the components of a nucleotide, hence it represents the selection of "Nucleotide".

Adenine and Guanine would be classified as the purines. Purines are one of the two types of nitrogenous bases found in DNA and RNA, the other being pyrimidines. Adenine and guanine are both purines because they have a double-ring structure, consisting of a six-membered ring fused to a five-membered ring. In contrast, thymine and cytosine are pyrimidines, which have a single-ring structure. Therefore, the correct answer is Adenine and Guanine.

The backbone of the DNA structure is made up of alternating phosphates and sugar molecules. These phosphates and sugars form a strong and stable structure that supports the DNA double helix. The phosphates provide a negative charge, while the sugars provide a backbone for the attachment of nucleotide bases. This alternating pattern of phosphates and sugars creates a stable and flexible structure that allows DNA to store and transmit genetic information. Nucleotides and bases are important components of DNA, but they are attached to the backbone rather than forming the backbone itself.

The diagram represents Griffith's experiment, where he observed that when a harmless bacteria strain (rough strain) was mixed with a heat-killed deadly strain (smooth strain), the mice still died. This suggests that something inside the bacteria has the ability to instruct and control what the bacteria does, as the rough strain must have acquired the ability to cause disease from the smooth strain. This conclusion is logical based on the experiment's results.

Hershey and Chase tested and confirmed the hypothesis that if DNA is truly the hereditary material emitted into the bacteria, then radioactively marked DNA will show up in the bacteria, not in the external liquid following the virus' activity. This means that they wanted to determine whether DNA or protein was responsible for transmitting genetic information. By using radioactive markers on DNA and protein, they were able to track the location of these molecules and found that the radioactively marked DNA was present in the bacteria, confirming that DNA is indeed the hereditary material.

The base represented in the purple color in the diagram is guanine. Here's why:

Structure: The purple molecule has two rings connected by a linker, which is characteristic of purine bases like guanine and adenine. Pyrimidine bases, like cytosine and thymine, have only one ring.

Position of the nitrogen atoms: The purple molecule has two nitrogen atoms on the top ring and one on the bottom ring, which matches the structure of guanine. Adenine has a different arrangement of nitrogen atoms on the rings.

Color coding: In many biology diagrams, purine bases are often colored red or purple, while pyrimidine bases are colored blue or green. While not definitive, the purple color of the molecule does support the identification as a purine base.