Nucleotides used in the replication of DNA __________ .
a. Carry energy
b. Are found in four forms, each with a deoxyribose sugar, a phosphate, and a base
c. Are present in cells as triphosphate nucleotides
d. All of the above are correct.

Verified step by step guidance

1. Step 1: Understand the structure of nucleotides used in DNA replication. Each nucleotide consists of three components: a deoxyribose sugar, a phosphate group, and a nitrogenous base. This corresponds to option (b).
2. Step 2: Recognize that nucleotides used in DNA replication are present as triphosphate nucleotides (e.g., dATP, dTTP, dGTP, dCTP). The triphosphate form provides the energy needed for the polymerization reaction. This corresponds to option (c).
3. Step 3: Recall that the energy for DNA synthesis comes from the high-energy phosphate bonds in the triphosphate nucleotides. When a nucleotide is added to the growing DNA strand, two phosphate groups are cleaved off, releasing energy. This relates to option (a).
4. Step 4: Since all the statements (a), (b), and (c) are correct and describe different aspects of nucleotides used in DNA replication, the correct answer is that all of the above are true.
5. Step 5: Summarize that nucleotides used in DNA replication carry energy, exist in four forms each with a deoxyribose sugar, phosphate, and base, and are present as triphosphate nucleotides, confirming that option (d) is the comprehensive choice.

Key Concepts

Structure of DNA Nucleotides

DNA nucleotides consist of three components: a deoxyribose sugar, a phosphate group, and one of four nitrogenous bases (adenine, thymine, cytosine, or guanine). These nucleotides are the building blocks of DNA and determine its genetic code.

Energy Carried by Nucleotide Triphosphates

Nucleotides used in DNA replication exist as triphosphates (dNTPs), which carry high-energy phosphate bonds. The energy released from breaking these bonds drives the polymerization of nucleotides into a DNA strand.

Forms and Availability of Nucleotides in Cells

In cells, nucleotides are present primarily as triphosphate forms, which serve as substrates for DNA polymerase during replication. The four types correspond to the four bases, ensuring accurate DNA synthesis.