Guide Questions Nucleotide 1. What are the common parts of a nucleotide? 2. What is the one part of a nucleotide that differs among different nucleotides? 3. List the different kinds of nitrogen bases. A nucleotide is a chemical compound called a nucleotide. It is named for the base that joins with a molecule of deoxyribose and phosphate to form a nucleotide. For example, if thymine attaches to deoxyribose, the molecule is called a thymine deoxyribose. 3. Complete the right side of the DNA molecule by matching the bases of the other nucleotides. It may be necessary to turn molecules upside down in order to make them fit. Guide Questions: 4. What is the pairing arrangement of the nitrogenous bases? Adenine pairs with thymine. 5. Are there always going to be an equal number of adenine and thymine nucleotides in a molecule? Why? Are there always going to be an equal number of guanine and cytosine nucleotides in a molecule? Why? Adenine always pairs with thymine, and guanine always pairs with cytosine. CILIC Con: GDC S ΤΑ S С?
The Correct Answer and Explanation is:
Answers to Guide Questions:
- What are the common parts of a nucleotide?
- A nucleotide consists of three parts: a phosphate group, a five-carbon sugar (either deoxyribose in DNA or ribose in RNA), and a nitrogenous base.
- What is the one part of a nucleotide that differs among different nucleotides?
- The nitrogenous base is the part that differs. There are four different nitrogenous bases in DNA.
- List the different kinds of nitrogen bases.
- The four nitrogenous bases in DNA are:
- Adenine (A)
- Thymine (T)
- Cytosine (C)
- Guanine (G)
- The four nitrogenous bases in DNA are:
- What is the pairing arrangement of the nitrogenous bases?
- In DNA, adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C).
- Are there always going to be an equal number of adenine and thymine nucleotides in a molecule? Why? Are there always going to be an equal number of guanine and cytosine nucleotides in a molecule? Why?
- Yes, there will always be equal numbers of adenine and thymine because they always pair together. Likewise, guanine always pairs with cytosine, so their quantities will also be equal. This is due to the base pairing rules that maintain the DNA’s double helix structure.
Textbook-Style Explanation
A nucleotide is the basic building block of nucleic acids such as DNA and RNA. Each nucleotide is made up of three main components: a phosphate group, a five-carbon sugar (deoxyribose in DNA and ribose in RNA), and a nitrogenous base. The nitrogenous base is the only part of the nucleotide that varies, and it determines the identity of the nucleotide. In DNA, there are four types of nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
In the structure of DNA, nucleotides are arranged in two long strands that form a double helix. The nitrogenous bases from each strand pair with one another through hydrogen bonds in a very specific way: adenine always pairs with thymine (A-T) and guanine always pairs with cytosine (G-C). This specific pairing is called complementary base pairing and ensures that the DNA can be accurately copied during processes like DNA replication.
Because of this base pairing rule, the number of adenine bases in a DNA molecule will always be equal to the number of thymine bases. Similarly, the number of guanine bases will always match the number of cytosine bases. This equality is known as Chargaff’s Rule, and it is essential for maintaining the uniform width and stable structure of the DNA double helix. The consistency of base pairing also allows scientists to determine the sequence of one DNA strand if they know the sequence of its complementary strand.
