Concept explainers
Videos
If a parental DNA strand has the base sequence A-T-T-G-C-A-C-T, DNA polymerase would synthesize a new strand with the sequence
a. A-T-T-G-C-A-C-T.
b. T-A-A-C-G-T-G-A.
c. C-G-G-T-A-C-A-G.
d. The sequence of the new strand cannot be determined from the information given.
Introduction:
Deoxyribonucleic acid (DNA) carrying the genetic information, is a double-helical structure. At the time of the replication, two strands of the DNA unwound from each other. The sole purpose of this mechanism is for the formation of the new strands which are complementary to each other. This is also known as Chargaff’s rule.
Answer to Problem 1MC
Correct answer:
According to the base pairing rule, if a parental DNA strand has A-T-T-G-C-A-C-T base sequence, its complementary strand will be formed having a T-A-A-C-G-T-G-A base sequence.
Explanation of Solution
Explanation for the correct statement:
Option (b) is given as, T-A-A-C-G-T-G-A. The formation of the new strands follows the complementarity rule. This states that A (adenine) will always pair with T (thymine) with a double bond whereas, G (guanine) will always pair with C (cytosine) with a triple bond. According to this rule, option (b) is correct.
Explanation for incorrect answers:
Option (a) is given as, A-T-T-G-C-A-C-T. Pairing either purine with purine or pyrimidine with a pyrimidine, imparts a strong repelling force thereby, hampering in the hydrogen bond formation between the bases. So, it is an incorrect answer.
Option (c) is given as, C-G-G-T-A-C-A-G. Formation of bonds depends upon the specific structure of the bases which allows them to form the hydrogen bond between them. Adenine shares only two atoms for the bond formation, which only welcomes thymine with its two atoms for the same. So, it is an incorrect answer.
Option (d) is given as the sequence of the new strand cannot be determined from the information given. Once the information about the bases is provided from one strand, it is possible to retrieve the other strand’s bases via Chargaff’s rule. As per the rule, A will always pair with T by two hydrogen bonds and G will always pair with C with three hydrogen bonds. So, it is an incorrect answer.
Hence, option (a), (c), and (d) are incorrect.
Therefore, it can be concluded that the retrieval of the other strand information at the time of replication is easy and useful. Once the information is provided about either of the strands, the further process can be studied with the help of complementary rule.
Want to see more full solutions like this?
Chapter 12 Solutions
Biology: Life on Earth (11th Edition)
- When two adjacent bases in the same strand of DNA dimerize (form a covalent bond between them), what happens to the DNA? a. the original strand of DNA now contains a new DNA sequence b. the original strand of DNA is prevented from opening during replication, so this section of DNA will not be replicated c. the original strand of DNA is methylated, which causes the bases to mismatch d. the original strand of DNA is kinked, which prevents DNA polymerase from working properly e. the original strand of DNA is unaffected, so no additional mutations arisearrow_forwardIn DNA replication, a primer is _____. a. what the original DNA strands are called b. a molecule that provides the energy for nucleotide attachments c. a regulatory protein that turns on the gene that starts DNA replication d. an enzyme that breaks the hydrogen bonds between base pairs e. a short piece of nucleic acid that serves as an attachment point for DNA polymerasearrow_forwardWhich of the following would be most likely to cause a mutation? A. the addition of nucleotides to the 3’ end of the growing strand B. the insertion of a mismatched nucleotide into a DNA strand C. the unwinding of the DNA strand D. the synthesis of short stretches of DNAarrow_forward
- Each time double-stranded (ds) DNA is replicated, the resulting copies of DNA include: A. One parent (original) strand and one daughter (new) strand B. Either two parent (original) strands or two daughter (new) strands C. Four parent strands D. Four daughter strandsarrow_forwardDuring DNA replication, the helicase enzyme binds to DNA and Select one: a. prevents the DNA strands from rewinding back into the helical shape b. cuts the double stranded DNA into single strands c. provides the starting point where new nucleotides can be added d. adds new nucleotides to the template strandarrow_forwardHow are nucleotides connected to each other in a single strand of DNA? A. The nitrogenous bases and acids link the separate nucleotides into a chain. B. The phosphate group of one nucleotide binds to the sugar on the next nucleotide. C. The hydroxy group of one nucleotide stabilizes the phosphate group of the adjacent nucleotide. D. The sugar of one nucleotide binds directly to the sugar of the adjacent nucleotide.arrow_forward
- During DNA replication: A. The two DNA strands separate, each strand then becomes a template for the assembly of a complementary strand. Each new DNA helix has one old strand with one new strand. B. The two DNA strands separate, each strand then becomes a template for the assembly of a similar strand. Each new DNA helix has one old strand with one new strand. C. The two DNA strands separate, each strand then becomes a template for the assembly of a similar strand. Each new DNA helix has two new strands. D. The two DNA strands separate, each strand then becomes a template for the assembly of an identical strand. Each new DNA helix has one old strand with one new strand.arrow_forwardDNA strands are anti-parallel and DNA polymerase can only synthesize DNA in a 5' to 3' direction. How does the enzyme synthesize both strands at the same time? A. The leading strand is sythesised in Okazaki fragments B. The lagging strand is synthesised in short Okazaki fragments. C. Only one strand is replicated. D. There are more than one DNA polymerase involved.arrow_forwardIn the dideoxy-sequencing reaction, what terminates DNA synthesis at a particular base? a. The absence of a base on the ddNTP halts the DNA polymerase. b. The ddNTP causes a break in the sugar–phosphate backbone. c. DNA polymerase will not incorporate a ddNTP into the growing DNA strand. d. The absence of a 3′-OH group on the ddNTP prevents the addition of another nucleotide.arrow_forward
- DNA polymerase adds nucleotides to Select one: a. the 5′ end, and the leading strand elongates in the 3′ to 5′ direction b. the 3′ end, and the leading strand elongates in the 5′ to 3′ direction c. the 5′ end, and the leading strand elongates in the 5′ to 3′ direction d. the 3′ end, and the leading strand elongates in the 3′ to 5′ directionarrow_forwardIn DNA replication, what is meant when we say it is “semi-conservative”? a. One new DNA molecule contains the parent strands and the other DNA molecule contains only new strands b. Both new DNA strands contain a parent strand and a template strand c. The new DNA molecules are exactly like the original strand d. Some of the genes are replicated, some aren’tarrow_forwardFrom which end of a strand of nucleic acid does DNA polymerase I REMOVE nucleotides? A) 5' B) 3' C) 2' D) N-term E) C-termarrow_forward
Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning