Textbook Question
For the following fragment of DNA, determine the number of hydrogen bonds and the number of phosphodiester bonds present:
5'-ACGTAGAGTGCTC-3'
3'-TGCATCTCACGAG-5'
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7. DNA and Chromosome Structure
DNA Structure
2:23 minutesProblem 8a
Textbook Question
The following figure (Figure 1.6) presents simplified depictions of nucleotides containing deoxyribose, a nucleotide base, and a phosphate group. Use this simplified method of representation to illustrate the sequence 3'-AGTCGAT-5' and its complementary partner in a DNA duplex.
What kind of bond joins the C to G within a single strand?
Verified step by step guidance1
Understand the structure of a DNA nucleotide: Each nucleotide consists of three components: a deoxyribose sugar, a phosphate group, and a nitrogenous base (A, T, G, or C). The sequence 3'-AGTCGAT-5' represents the order of these bases in a single strand of DNA.
Illustrate the sequence 3'-AGTCGAT-5': Start by drawing the deoxyribose sugar and phosphate backbone. Attach the nitrogenous bases (A, G, T, C, G, A, T) to the 1' carbon of each sugar, ensuring the 3' and 5' ends are labeled appropriately.
Determine the complementary strand: DNA is double-stranded, and the complementary strand is formed by pairing A with T and G with C. Write the complementary sequence in the 5' to 3' direction, which will be 5'-TCAGCTA-3'.
Illustrate the DNA duplex: Draw the complementary strand antiparallel to the original strand (3'-AGTCGAT-5'). Connect the complementary bases (A-T and G-C) with hydrogen bonds. Remember, A-T pairs have two hydrogen bonds, and G-C pairs have three hydrogen bonds.
Answer the bond question: Within a single strand, the bond joining the C to the G is a phosphodiester bond. This covalent bond links the 3' carbon of one nucleotide's sugar to the 5' phosphate group of the next nucleotide, forming the sugar-phosphate backbone of the DNA strand.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Nucleotides
Nucleotides are the building blocks of DNA and RNA, consisting of three components: a sugar (deoxyribose in DNA), a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, or thymine in DNA). The sequence of these nucleotides encodes genetic information, and their arrangement determines the structure and function of nucleic acids.
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Complementary Base Pairing
In DNA, complementary base pairing refers to the specific pairing of nitrogenous bases across the two strands of the double helix. Adenine pairs with thymine (A-T) and guanine pairs with cytosine (G-C) through hydrogen bonds, which stabilize the DNA structure and ensure accurate replication and transcription of genetic information.
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Phosphodiester Bond
A phosphodiester bond is a type of covalent bond that links nucleotides together in a single strand of DNA or RNA. It forms between the phosphate group of one nucleotide and the hydroxyl group on the sugar of another, creating a sugar-phosphate backbone that provides structural integrity to the nucleic acid molecule.
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