Sometimes DNA polymerase makes a mistake, and the wrong nucleotide is added to the growing DNA strand. With regard to pyrimidines and purines, two general types of mistakes are possible. The addition of an incorrect pyrimidine instead of the correct pyrimidine (e. g. adding cytosine where thymine should be added) is called a transition. If a pyrimidine is incorrectly added to the growing strand instead of purine (e.g. adding cytosine when an adenine should be added), this type of mistake is called a transversion. If a transition or transversion is not detected by DNA polymerase, a mutation is created the permanently changes the DNA sequence. Though both types of mutations are rare, transition mutations are more frequent than transversion mutations. What are at least three explanations as to why this is the case?

Sometimes DNA polymerase makes a mistake, and the wrong nucleotide is added to the growing DNA strand. With regard to pyrimidines and purines, two general types of mistakes are possible. The addition of an incorrect pyrimidine instead of the correct pyrimidine (e. g. adding cytosine where thymine should be added) is called a transition. If a pyrimidine is incorrectly added to the growing strand instead of purine (e.g. adding cytosine when an adenine should be added), this type of mistake is called a transversion. If a transition or transversion is not detected by DNA polymerase, a mutation is created the permanently changes the DNA sequence. Though both types of mutations are rare, transition mutations are more frequent than transversion mutations. What are at least three explanations as to why this is the case?

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter11: Genome Alterations: Mutation And Epigenetics

Section: Chapter Questions

Problem 18QP: Replication involves a period of time during which DNA is particularly susceptible to the...

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Sometimes DNA polymerase makes a mistake, and the wrong nucleotide is added to the growing DNA strand. With regard to pyrimidines and purines, two general types of mistakes are possible. The addition of an incorrect pyrimidine instead of the correct pyrimidine (e.g., adding cytosine where thymine should be added) is called a transition. If a pyrimidine is incorrectly added to the growing strand instead of purine (e.g., adding cytosine where an adenine should be added), this type of mistake is called a transversion. If a transition or transversion is not detected by DNA polymerase, a mutation is created that permanently changes the DNA sequence. Though both types of mutations are rare, transition mutations are more frequent than transversion mutations. Based on your understanding of DNA replication and DNA polymerase, offer three explanations why transition mutations are more common.
During template-directed synthesis of a new DNA strand it can happen, if there are simple repeated sequences, that either the template strand or the strand being synthesized "slips" a short distance, and this can change the number of repeating sequence units in that stretch of repeated sequence. Which of the following processes involve such slippage? More than one answer is correct. Options: The increase in genomic copy number of a DNA transposon by transposition from a location behind a replication fork to a location ahead of the fork. Introduction of indels during DNA replication. The initial unwinding of the DNA duplex during replication by helicase. Increasing lengths of CAG trinucleotide repeats in the huntingtin gene giving rise to Huntington disease. Synthesis of primer by primase during DNA replication.
A solution contains DNA polymerase and the Mg ²+ salts of dATP, dGTP, dCTP, and TTP. The following DNA molecules are added to aliquots of this solution. Which of them would lead to DNA synthesis? (a) A single-stranded closed circle containing 1000 nucleotide units. (b) A double-stranded closed circle containing 1000 nucleotide pairs. (c) A single-stranded closed circle of 1000 nucleotides base-paired to a linear strand of 500 nucleotides with a free 3' -OH terminus. (d) A double-stranded linear molecule of 1000 nucleotide pairs with a free 3’-OH group at each end.
A DNA strand has the following sequence: 5’-GAACCCGATGGCGATACATTTACCAGATCACCAGC-3’ In which direction would DNA polymerase slide along this strand (from left to right or from right to left)? If this strand was used as a template by DNA polymerase, what would be the sequence of the newly made strand? Indicate the 5’ and 3’ ends of the newly made strand.
DNA polymerase occasionally incorporates the wrong nucleotide during DNA replication. If left unrepaired, the base-pair mismatch that results will lead to mutation in the next replication. As part of a template strand, the incorporated wrong base will direct the incorporation of a base complementary to itself, so the bases on both strands of the DNA at that position will now be different from what they were before the mismatch event. The MER-minus strain of yeast does not have a functional mismatch excision repair system, but it has normal base excision repair and nucleotide excision repair systems. Which of the following statements is correct about differences in the mutation spectrum between MER-minus and wildtype yeast? More than one answer is correct. Options: More point mutations will arise in MER-minus yeast. Fewer point mutations will arise in MER-minus yeast as compared with wildtype. Of the total point mutations that…
The purpose of DNA gyrase in replication is: to relieve positive supercoiling induced by unwinding the DNA during replication. to induce tighter coiling in supercoils. to remove the RNA primers from the lagging strand at each Okazaki fragment to start unwinding and separate the DNA to initiate replication to provide energy to remove a diphosphate fragment from each nucleoside triphosphate.
Deamination of adenine results in the formation of hypoxanthine. Hypoxanthine selectively base pairs with cytosine. If this error is not corrected, what base pair can the original A·T base pair be converted to after cycles of DNA replication?a) G·C b) C·G c) T·A d) A·G
Which of the following statements is TRUE? Synthesis of the lagging strand requires more DNA helicase enzymes than synthesis of the leading strand. The lagging strand is synthesized in a semiconservative fashion while the leading strand is synthesized in a conservative fashion. The leading strand is replicated continuously for the entire length of the chromosome, e.g. while the lagging strand has multiple origins of replication The lagging strand has a higher mutation rate than the leading strand. None of the answers are true.
Single-stranded binding proteins (SSBPs) bind to single-stranded DNA at the replication fork and prevent formation of short hairpin sequences that would otherwise impede DNA synthesis. What sorts of sequences in single-stranded DNA might be able to form a hairpin? Write out an example of a sequence that could form a 5-nucleotide hairpin loop, and draw it.
Which of the following types of DNA damage would be hardest to repair using the DNA repair pathways?A. Complete removal of three nucleotides in the middle of one strand.B. A covalent bond between a base on one strand and a base on the complementary strand.C. Incorporation of a sugar other than deoxyribose into one strand.D. Covalent attachment of a short polypeptide to a single base.E. A covalent bond between a base and a deoxyribose on the same strand. Please explain why it's B
Which of the following best explains the leading daughter DNA strand? The leading strand is synthesized by the enzyme primase. It is polymerized discontinuously by DNA polymerase from 5' - 3' direction which leaves gaps knowns as Okazaki fragments. The gaps within the leading strand are sealed by DNA ligase. It is polymerized continuously by DNA polymerase from 5' - 3' direction.
Sliding-clamp proteins load polymerase onto the primer and maintain its stable association with the template. true or false? DNA polymerases add a deoxyribonucleotide triphosphate to the 3' hydroxyl group of a growing DNA chain (the primer strand). true or false?