Biotechnology Quiz: Multiple Choice Questions

Adenine and thymine pair with two hydrogen bonds because they have complementary shapes and sizes that allow them to fit together. Adenine has a flat structure with two hydrogen bond donor sites, while thymine has a complementary shape with two hydrogen bond acceptor sites. This allows adenine and thymine to form a stable base pair in DNA. The other options, adenine and cytosine, and cytosine and guanine, form three hydrogen bonds, making them incorrect answers.

Transcription is the process by which an RNA molecule, specifically mRNA, is synthesized from a DNA template. During transcription, the DNA double helix unwinds and one strand of the DNA acts as a template for the synthesis of a complementary mRNA molecule. This process occurs in the nucleus of eukaryotic cells and is essential for gene expression, as it allows the genetic information encoded in DNA to be transcribed into a form that can be used to produce proteins during translation. Therefore, transcription is the correct term for the formation of mRNA from DNA.

DNA differs from RNA in all of the above mentioned ways. DNA contains deoxyribose sugar instead of ribose sugar found in RNA. Additionally, DNA contains thymine base while RNA contains uracil base. Finally, DNA has the property of replication, meaning it can make copies of itself, while RNA does not have this ability. Therefore, the correct answer is all of the above.

GMO (Genetically Modified Organisms) is not a tool of genetic engineering, but rather a product or outcome of genetic engineering. Genetic engineering involves the use of tools such as vectors (such as plasmids or viruses) to transfer foreign DNA into an organism, enzymes (such as restriction enzymes or DNA ligase) to manipulate and modify DNA, and foreign DNA itself, which is introduced into an organism to alter its genetic makeup. GMOs are organisms that have been genetically modified using these tools.

Endonuclease is the correct answer because it is an enzyme that cuts the bonds of the DNA molecule at the origin of replication. This enzyme plays a crucial role in DNA replication by creating breaks in the DNA strand, allowing for the initiation of replication. It specifically targets and cuts the phosphodiester bonds within the DNA molecule, separating the two strands and facilitating the replication process. DNA polymerase, DNA gyrase, and DNA ligase are also involved in DNA replication but do not directly cut the bonds at the origin of replication.

In recombinant DNA technology, a plasmid vector is cleaved using the same enzyme that cleaves the donor DNA. This is because the same enzyme is used to create compatible sticky ends on both the plasmid vector and the donor DNA, allowing them to be joined together. By using the same enzyme, the sticky ends produced will have complementary base pairs, ensuring a strong and stable bond between the plasmid vector and the donor DNA. This is crucial for successful insertion of the desired DNA fragment into the plasmid vector during the cloning process.

Extranuclear genetic material refers to genetic material that is found outside of the nucleus. In eukaryotic cells, this genetic material can be found in organelles such as mitochondria and plastids. Mitochondria have their own DNA and are responsible for energy production in the cell. Plastids, on the other hand, are involved in various functions such as photosynthesis in plants. Therefore, the correct answer is mitochondria and plastids.

The number of phosphodiester bonds in a DNA strand is equal to the number of nucleotides minus one. Since the DNA strand has 35 nucleotides, there would be 34 phosphodiester bonds.

DNA gyrase is an enzyme that is required to release the tension imposed by uncoiling of strands. It is responsible for introducing negative supercoils in the DNA molecule, which helps to relieve the torsional strain generated during DNA replication and transcription. This enzyme is particularly important in bacteria, as it allows for the efficient unwinding and separation of DNA strands during these processes. DNA gyrase achieves this by breaking and rejoining DNA strands, effectively relieving the tension and preventing DNA damage.

Rhizobium meliloti is the correct answer because it is a bacterium that forms a symbiotic relationship with leguminous plants, such as clover and alfalfa, to fix nitrogen. The Nif gene, responsible for nitrogen fixation, is introduced into cereal crops like wheat through cloning, and Rhizobium meliloti is commonly used as a source of this gene.