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a)
Interpretation:
Long strand of DNA have the higher melting temperature than a shorter one, the reason has to be explained.
Concept Introduction:
Composition of
Base pairing in DNA: The two strands of the DNA double helix run in the opposite directions: one in 5’ to 3’ direction and other from 3’ to 5’ direction (complementary strand). The hydrogen bonding between two strands enhances the stability of the DNA; where the alignment of hydrophobic nitrogenous bases in the interior and hydrophilic phosphate and sugar groups on the exterior, is present that enhance the stability too. Adenine and thymine gives a pair forming two hydrogen bonds and cytosine and guanine gives rise to another pair forming three hydrogen bonds.
Melting temperature of DNA: On Heating DNA, (the process of denaturing the strand) the strand is unfolded or uncoiled.
b)
Interpretation:
The higher melting point is for either DNA with high percentage of G – C base pairs or high percentage of A – T base pairs has to be accounted.
Concept Introduction:
Composition of nucleic acid: Nucleic acid is a polymer of nucleotides. Each nucleotide has three parts: a sugar, a nitrogenous base, and a phosphate group. Two nucleotides are joined by phosphate diester linkage where a free phosphate on 5’ carbon of one nucleotide and a free –OH group on 3’ carbon of another nucleotide is linked.
Base pairing in DNA: The two strands of the DNA double helix run in the opposite directions: one in 5’ to 3’ direction and other from 3’ to 5’ direction (complementary strand). The hydrogen bonding between two strands enhances the stability of the DNA; where the alignment of hydrophobic nitrogenous bases in the interior and hydrophilic phosphate and sugar groups on the exterior, is present that enhance the stability too. Adenine and thymine gives a pair forming two hydrogen bonds and cytosine and guanine gives rise to another pair forming three hydrogen bonds.
Melting temperature of DNA: On Heating DNA, (the process of denaturing the strand) the strand is unfolded or uncoiled.
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Chapter 26 Solutions
Modified Mastering Chemistry With Pearson Etext -- Standalone Access Card -- For Fundamentals Of General, Organic, And Biological Chemistry (8th Edition)
- The base composition of one of the DNA chains of a DNA double helix contains 18 mol-%A, 35 mol-%T, 26 mol-%C, and 21 mol-%G (a) What is the base composition of the complementary DNA chain? (b) Is the total amount of purine bases equal to the total amount of pyrimidine bases for the DNA double helix?arrow_forwardWhen DNA is heated, it denatures; that is, the strands separate because hydrogen bonds are broken and some base-stacking and hydrophobic interactions are disrupted. The higher the temperature, the larger the number of hydrogen bonds that are broken. After reviewing DNA base pair structure, determine which of the following molecules will denature first as the temperature is raised. Explain your reasoning. a. 5′-GCATTTCGGCGCGTTA-3′ 3′-CGTAAAGCCGCGCAAT-5′ b. 5′-ATTGCGCTTATATGCT-3′ 3′-TAACGCGAATATACGA-5′arrow_forwardWhich would you expect to have a higher entropy: DNA in its wellknown double-helical form, or DNA with the strands separated?arrow_forward
- In a DNA Double helix ,why doesn't an A or T form two hydrogen bonds(out of the three possible) with G or C? Explain in detail.arrow_forwardSuppose a piece of DNA is cut into four fragments of varying sizes. Where would you expect to find the larger fragments on the gel (top, middle, or bottom)? Why? Suppose you had 1000 pieces of each of the four fragments, how many bands would appear on the gel?arrow_forwardThe double helical structure of DNA is intrinsically unstable and easily dissociates to form two separate strands. Why? How does this affect the two key biological functions of chromosomal DNA? What would happen if the DNA helices were too stable?arrow_forward
- DRAW A DNA STRAND WITH 10 ADENINE BASES FOLLOWED BY 10 CYTOSINE BASES. IF THAT SAME STRAND BONDED TO A STRAND OF 15 THYMINE BASE AND 5 GUANINE BASES, HOW WOULD THE DOUBLE HELIC SHAPE VARY FROM A TYPICAL DNA DOUBLE HELIX?arrow_forwardDraw the structure of deoxyribose and number the carbon atoms.Describe the numbering of the carbon atoms in deoxyribose withregard to the directionality of a DNA strand. In a DNA doublehelix, what does the term antiparallel mean?arrow_forwardwhy can we not describe the “average” behavior of a DNA molecule? Why is it improbable that proteins needed for DNA structure, for example, form spontaneously from random amino acids?arrow_forward
- What are the features that make the structure of the DNA stable? Explain why the DNA is the genetic material.arrow_forwardIn proteins, a peptide read from the N terminal to the C terminal. Is there a kind of direction in DNA/RNA as well? Briefly explain. What does Chargaff’s rules mean? Who proposed DNA was a double helix? In what decade? If one DNA single strand has the sequence 5’-AATGCAA-3’, what is the sequence of its complementary strand? When DNA replicates, how is it able to “unwind” its double helix?arrow_forwardEach nucleotide pair of a DNA double helix weighs about 1 × 10 −21 g. The human body contains approximately 0.5 g of DNA. How many nucleotide pairs of DNA are in the human body? If you assume that all the DNA in human cells is in the B-DNA form, how far would the DNA reach if stretched end to end?arrow_forward
Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning