Test: DNA Structure And Function! Quiz

A nucleotide is the correct answer because it is the basic unit of structure in a DNA molecule. Nucleotides are composed of a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine). These nucleotides join together through phosphodiester bonds to form the DNA molecule, with the nitrogenous bases pairing up (adenine with thymine and cytosine with guanine) to create the double helix structure. Nucleoside is not the correct answer as it lacks the phosphate group, nucleolus is a structure within the nucleus of a cell, and nuclein is an outdated term for nucleic acids.

In DNA, adenine always pairs with thymine, forming a specific base pair. This means that the amount of adenine will always be equal to the amount of thymine in DNA. The other options, cytosine, uracil, guanine, and ATP, are not always equal in amount to adenine in DNA.

The 5' - 3' and 3' - 5' of complementary strands is called antiparallel because they run in opposite directions. In DNA, one strand runs from the 5' end to the 3' end, while the other strand runs from the 3' end to the 5' end. This antiparallel arrangement is important for DNA replication and the functioning of enzymes involved in DNA synthesis.

Complementary base pairing refers to the specific pairing of nucleotide bases in DNA. It follows a strict rule where adenine (purine base) always pairs with thymine (pyrimidine base), and cytosine (pyrimidine base) always pairs with guanine (purine base). This pairing is essential for DNA replication and transcription processes. Therefore, the statement that complementary base pairing always pairs a purine base with a pyrimidine base is true.

The X-ray diffraction photography of Rosalind Franklin and Maurice Wilkins provided evidence that DNA has a double helix structure. This means that the DNA molecule consists of two strands that are twisted around each other in a helical shape. The X-ray diffraction pattern produced by Franklin and Wilkins showed a distinct X shape, indicating the presence of a helix. This discovery was crucial in understanding the overall structure of DNA and its role in genetic information storage and replication.

The bonds between W and X are hydrogen bonds. Hydrogen bonds occur when a hydrogen atom is attracted to an electronegative atom, such as oxygen or nitrogen. In this case, there is likely a hydrogen atom bonded to an electronegative atom in W, and another electronegative atom in X that is able to form a hydrogen bond with it. Hydrogen bonds are relatively weak compared to covalent or ionic bonds, but they play an important role in stabilizing the structure of molecules and facilitating interactions between molecules.

The correct answer is "Genome". The term "genome" refers to the complete set of genetic material or genes present in an organism. It includes all the DNA sequences, including both coding and non-coding regions, that make up an individual's genetic makeup. This term is used to describe the entire collection of genes that members of a species share, encompassing all the hereditary information that is passed on from one generation to the next.

The 5' and 3' on the diagram indicate the direction in which a strand of DNA is "read". DNA strands have a specific orientation, with one end referred to as the 5' end and the other end as the 3' end. This orientation is important because DNA is synthesized in a specific direction, with new nucleotides being added to the 3' end of the growing strand. The 5' to 3' directionality is also important for DNA replication and transcription processes.

Chargaff's rules, discovered by Austrian biochemist Erwin Chargaff, state that in DNA, the amount of adenine (A) is equal to the amount of thymine (T), and the amount of guanine (G) is equal to the amount of cytosine (C). This means that different species have different base compositions, as the proportions of A, T, G, and C can vary. Therefore, the statement that "Chargaff's rules showed that different species contain differing base compositions" is true.

Watson and Crick's original model of DNA had the complementary bases located on the inside of the helix, with the sugar-phosphate backbone on the outside. This model, known as the double helix structure, was a groundbreaking discovery in understanding the structure of DNA.

The genetic material is responsible for storing information, replicating itself, and undergoing mutation. However, it does not directly catalyze chemical reactions. Instead, enzymes and other proteins are responsible for catalyzing chemical reactions in the cell.

The cells of prokaryotes are haploid, meaning they contain only one set of chromosomes. This is in contrast to somatic cells, which are diploid and contain two sets of chromosomes. The term "haploid" refers to the number of sets of chromosomes present in a cell, and prokaryotes typically have a single circular chromosome. This characteristic allows for efficient replication and adaptation to changing environments in prokaryotes.

The bonds between Y and Z are phosphodiester bonds. Phosphodiester bonds are formed between a phosphate group and two sugar molecules in a DNA or RNA molecule. These bonds are strong and stable, allowing for the formation of the backbone of the DNA or RNA molecule. Polar covalent bonds involve the unequal sharing of electrons between atoms, hydrogen bonds occur when a hydrogen atom is attracted to an electronegative atom, and ethers are organic compounds characterized by an oxygen atom bonded to two alkyl or aryl groups.

Histone proteins and supercoiling play a crucial role in keeping an entire set of our genes in the nucleus of every cell. Histone proteins help in organizing and packaging DNA into a compact structure called chromatin, which further condenses to form chromosomes. Supercoiling refers to the coiling of DNA upon itself, which helps in further compacting the genetic material. Together, histone proteins and supercoiling ensure that all the genes are tightly packed and protected within the nucleus, allowing efficient storage and regulation of genetic information.

The Griffiths experiment showed that something physically present in bacteria causes disease. This experiment involved injecting mice with different strains of bacteria, and Griffiths observed that when mice were injected with heat-killed virulent bacteria, they still developed pneumonia. This indicated that the disease-causing factor was not the living bacteria themselves, but rather something physically present in the bacteria. This discovery revolutionized the understanding of infectious diseases and paved the way for further research on bacterial virulence factors.

Friedrich Miescher, a Swiss biochemist, is credited with the discovery of nucleic acids. In 1869, he isolated a substance from the nuclei of pus cells, which he called "nuclein." This substance was later identified as nucleic acid. Miescher's discovery laid the foundation for further research on nucleic acids and their role in genetics and heredity.

The Hershey and Chase experiment used radioactive Sulfur and Phosphorus to trace the passing on of certain molecules. The experiment showed that when the bacteriophages infected the bacteria, only the radioactive DNA from the phages was found inside the bacteria, while the radioactive proteins remained outside. This indicated that the DNA was the genetic material being passed on from one generation of viruses to the next. Therefore, the statement "Offspring viruses contain physical portions of parental DNA" best reflects their results.