Pre-uts Quiz In Molecular Biology 2009

PCR stands for polymerase chain reaction, which is a technique used to amplify a specific region of DNA. It involves multiple cycles of DNA denaturation, primer annealing, and DNA synthesis using a DNA polymerase enzyme. This allows for the exponential amplification of the targeted DNA sequence. PCR is a powerful tool in molecular biology and is widely used in various applications such as gene cloning, DNA sequencing, and diagnostic testing. It is an essential method for studying genes and their functions.

A cloning vector is a DNA molecule that is able to replicate inside a host cell and can be used to clone other fragments of DNA. In this context, the plasmid carrying genes coding for enzymes that enable the host bacterium to withstand the growth-inhibitory effects of two antibiotics (ampicillin and tetracycline) is acting as a cloning vector. The genes on the plasmid serve as selectable markers, allowing for the identification of cells that have taken up the plasmid. Therefore, the correct answer is G, Cloning vector.

Restriction endonucleases are enzymes that cut DNA molecules at specific nucleotide sequences. They are used in molecular biology techniques to create fragments of DNA for analysis or manipulation. In this question, the phrase "An enzyme that cuts DNA molecules at a limited number of specific nucleotide sequences" matches with the term "Restriction endonuclease" (option J). The repetition of option J in the answer indicates that this term is used more than once in the matching exercise.

Ligases are enzymes that join DNA molecules together by synthesizing phosphodiester bonds between nucleotides. In this case, the plasmid carries genes coding for enzymes that enable the host bacterium to withstand the growth-inhibitory effects of two antibiotics. Therefore, ligases are needed to join the DNA fragments together to create the plasmid. The use of ligases is essential in molecular biology techniques for cloning and creating recombinant DNA molecules.

A primer is an oligonucleotide that is used in a polymerization reaction to produce a complementary DNA or RNA strand. In molecular biology techniques such as PCR, a primer is necessary to initiate the synthesis of new DNA strands. It provides a starting point for DNA polymerase to bind and begin copying the target DNA sequence. Therefore, in the context of the given statement, the primer is needed to amplify the genes coding for enzymes that enable the host bacterium to withstand the growth-inhibitory effects of antibiotics.

Sticky ends, also known as cohesive ends, are single-stranded overhangs at the ends of a DNA molecule. They are produced by restriction endonucleases, which cut DNA at specific nucleotide sequences. The complementary sticky ends of two DNA molecules can easily bind together, allowing for the joining of different DNA fragments. This is important in molecular biology techniques such as cloning, where DNA fragments are inserted into a vector, and PCR, where specific regions of DNA are amplified. Sticky ends play a crucial role in these processes by facilitating the precise and efficient manipulation of DNA molecules.

The correct answer is M, Chain termination method. This refers to the method of DNA sequencing developed by Fred Sanger. It involves enzymatic synthesis of polynucleotide chains that terminate at specific nucleotide positions. This method uses modified nucleotides that lack a 3' hydroxyl group, preventing further chain elongation. The terminated fragments are then separated by size using gel electrophoresis, allowing the determination of the DNA sequence.

pBR322 is a plasmid that carries genes coding for enzymes that allow the host bacterium to resist the inhibitory effects of ampicillin and tetracycline. It is a cloning vector, which means it can be used to replicate and clone other fragments of DNA. pBR322 also contains selectable markers, which are genes that confer a recognizable characteristic on cells containing the vector or recombinant DNA derived from the vector. Therefore, the correct answer is C, pBR322.

The correct answer is M, Chain termination method. This refers to the method of DNA sequencing developed by Fred Sanger. In this method, DNA is synthesized using DNA polymerase and a mixture of normal deoxynucleotides (dNTPs) and modified dideoxynucleotides (ddNTPs) that lack a 3' hydroxyl group. The incorporation of a ddNTP into the growing DNA chain terminates synthesis, resulting in a series of DNA fragments of different lengths. These fragments are then separated by size using gel electrophoresis, and the sequence can be determined by reading the positions of the terminated fragments.

RNA lacks the base thymine (which is found in DNA) and has uracil instead. This is because RNA and DNA are both nucleic acids, but they have slightly different structures. DNA contains the base thymine, while RNA replaces thymine with uracil. This difference in bases is important because it affects the pairing of nucleotides during DNA replication and RNA transcription. Thymine pairs with adenine in DNA, while uracil pairs with adenine in RNA. This distinction allows RNA to serve as a template for protein synthesis, while DNA remains as the genetic material.

The correct answer is "The totality of genetic information belonging to a cell or an organism." This statement accurately describes a genome as the complete set of genetic material, including all the genes and non-coding DNA, present in a cell or an organism. It encompasses all the hereditary information that determines the characteristics and functions of an individual.