Which of the following is true with regards to the leading strand during DNA replication?
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Both the strands of the parental DNA double helix serve as templates No worries! We‘ve got your back. Try BYJU‘S free classes today! On the template with polarity 3’ No worries! We‘ve got your back. Try BYJU‘S free classes today! On the template with polarity 5’ No worries! We‘ve got your back. Try BYJU‘S free classes today! Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses Solution The correct option is DAll the aboveDuring DNA replication, both the strands of the parental DNA double helix serve as templates. A template strand is simply the strand from which a new complementary strand is synthesised. Complementary to the 3'→5’ template, the leading strand is synthesised along the 5'→3’ direction. The lagging strand is synthesised discontinuously, and complementary to the 5’→3’ template. Ultimately, one round of DNA replication results in the splitting of a single parental DNA molecule to form two daughter DNA double helices, exactly identical to the parental DNA.The Elements of Life In biology, the elements of life are the essential building blocks that make up living things. They are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. The first four of these are the most important, as they are used to construct the molecules that are necessary to make up living cells. These elements form the basic building blocks of the major macromolecules of life, including carbohydrates, lipids, nucleic acids and proteins. Carbon is an important element for all living organisms, as it is used to construct the basic building blocks of life, such as carbohydrates, lipids, and nucleic acids. Even the cell membranes are made of proteins. Carbon is also used to construct the energy-rich molecules adenosine triphosphate (ATP) and guanosine triphosphate (GTP). Hydrogen is used to construct the molecules water and organic compounds with carbon. Hydrogen is also used to construct ATP and GTP. Nitrogen is used to construct the basic building blocks of life, such as amino acids, nucleic acids, and proteins. It is also used to construct ATP and GTP. Oxygen is used to construct the basic building blocks of life, such as carbohydrates, lipids, and nucleic acids. It is also used to construct ATP and GTP. Phosphorus is used to construct the basic building blocks of life, such as carbohydrates, lipids, and nucleic acids. If you're seeing this message, it means we're having trouble loading external resources on our website. If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. All GRE Subject Test: Biochemistry, Cell, and Molecular Biology ResourcesWhat 3' functional group must be free in order to add the next nucleotide during DNA synthesis? Possible Answers: Amine Hydroxyl Carboxylic acid Phosphate Explanation: DNA synthesis requires a free 3' hydroxyl (-OH) group to add the next nucleotide base. Drugs that block DNA replication often have a modified 3' hydroxyl group, which prevents the addition of the next nucleotide and results in chain termination. Magnesium is a necessary component of DNA polymerization, but is not found in the DNA molecule. What is the purpose of magnesium in the polymerization of DNA? Possible Answers: It binds to the two leaving groups during the DNA polymerization reaction It is a cofactor for DNA polymerase III None of these answers are correct It binds nucleotides in the cytosol and helps import them into the nucleus Correct answer: It binds to the two leaving groups during the DNA polymerization reaction Explanation: In order for a nucleotide to be added to a growing DNA molecule, two reactions must occur involving magnesium. First the 3'-OH group on the end of the growing DNA molecule is bound by magnesium and removed from the deoxyribose sugar so that the phosphate from the new nucleotide can bind in its place. Second, nucleotides exist in the nucleus as dNTPs (deoxyribose nucleoside triphosphates). This means that there are three phophates attached to the deoxyribose sugar on the free nucleotide. Only one phosphate (the primary phosphate) binds to the growing DNA molecule. Magnesium binds the other two phosphates and removes them from the dNTP so that the reaction can continue. Which enzyme is responsible for removing the RNA primers added during DNA replication? Possible Answers: DNA polymerase I DNA polymerase III Primase DNA ligase Correct answer: DNA polymerase I Explanation: In order for DNA polymerase III to lengthen the new DNA strands, RNA primers must be put in place as a template. Once the strands are done being made, the RNA primers are removed and replaced with DNA nucleotides by DNA polymerase I. What is the main reason for there being both a leading and a lagging strand during DNA replication? Possible Answers: DNA polymerase can only read in the 3'-to-5' direction There are not enough RNA primers to have both strands be synthesized simultaneously DNA polymerase can only synthesize one strand at a time Only one strand is available to be read at any given time Correct answer: DNA polymerase can only read in the 3'-to-5' direction Explanation: When the DNA helix is opened by DNA helicase, both strands are available to be read by DNA polymerase. However, since DNA polymerase can only read from 3'-to-5', one strand must be synthesized in segments (called Okazaki fragments), rather than one continuous strand. The leading strand is read in the 3'-to-5' direction away from the replication fork, while the lagging strand is read in the 3'-to-5' direction toward the replication fork. This results in a leading and a lagging strand due to the antiparallel structure of DNA. Which of the following enzymes is not involved in the process of replicating DNA in a replication bubble? Possible Answers: Topoisomerase Polymerase Methyltransferase Ligase Primase Correct answer: Methyltransferase Explanation: The correct answer is methyltransferase, which is involved in the methylation of DNA post transcription. The other 4 enzymes are directly involved in the DNA replication bubble. Topoisomerase unwinds the replication fork, polymerase elongates new DNA strands, primase creates primers on the discontinuous 5' to 3' side of the replication bubble, and ligase joins the Okazaki fragments on the discontinous 5' to 3' side. Why do microsatellites, such as the one that causes Huntington's disease, occur in genomes? Possible Answers: Microsatellites are caused by insertion of DNA material by viruses The body is better able to interpret microsatellite sequences into proteins, so they are more common in the genome Microsatellites are a result of very slow evolutionary processes None of these DNA polymerase "stutters" on repeated bases during DNA replication and adds or deletes bases Correct answer: DNA polymerase "stutters" on repeated bases during DNA replication and adds or deletes bases Explanation: Microsatellites are generally composed of many repeated bases over and over again, which result from mistakes by DNA polymerase. Polymerase tends to create more errors in cases where many bases are repeated, often creating neutral mutations that evolve extremely quickly. Which of the following is true with regards to the leading strand during DNA replication? Possible Answers: It can read the template strand in the 5' to 3' direction. It does not require an RNA primer. It requires the joining of Okazaki fragments. It only requires one DNA polymerase III in order to complete the strand. Correct answer: It only requires one DNA polymerase III in order to complete the strand. Explanation: In DNA replication, the synthesis of new strands can be accomplished in both directions. In each direction, you will have both a leading strand and a lagging strand. While both new strands require an RNA primer in order to get started, the leading strand can be continuously synthesized because the template strand is exposed in a 3' to 5' direction. As a result, only one DNA polymerase III is required for this strand. Keep in mind that while the new strand is synthesized in a 5' to 3' direction, the template strand is read in a 3' to 5' direction. This allows for the new strand to be complementary to the template. All GRE Subject Test: Biochemistry, Cell, and Molecular Biology ResourcesWhat is the leading strand during DNA replication?The leading strand is a single DNA strand that, during DNA replication, is replicated in the 3' – 5' direction (same direction as the replication fork). DNA is added to the leading strand continuously, one complementary base at a time.
What is true about the leading strand of DNA?The leading strand is synthesized continuously in the forward direction (same direction as the movement of the replication fork). On the other hand, the other parent strand that runs in the 5' to 3' direction is not synthesized continuously but rather piece-by-piece.
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