Here are the answers to your questions: 1. What is a DNA nucleotide? What are its three (3) components? A DNA nucleotide is the basic building block (monomer) of a DNA strand. It is a molecule composed of three distinct components. The three (3) components of a DNA nucleotide are: 1. Deoxyribose sugar (a five-carbon sugar) 2. Phosphate group 3. Nitrogenous base (Adenine, Guanine, Cytosine, or Thymine) 2. How do DNA strands join together to form a 'double helix'? DNA strands join together to form a double helix through specific interactions between their nitrogenous bases and the sugar-phosphate backbone. The two DNA strands are held together by hydrogen bonds* that form between complementary nitrogenous bases on opposite strands. Adenine (A) on one strand always pairs with Thymine* (T) on the other strand, forming two hydrogen bonds. Guanine (G) on one strand always pairs with Cytosine* (C) on the other strand, forming three hydrogen bonds. These hydrogen bonds create a stable ladder-like structure, which then twists into the characteristic double helix shape. The sugar-phosphate backbones form the outer rails of the helix. 3. What are the four (4) bases that make up the four (4) nucleotides found in DNA? What is the base-pairing rule? The four (4) nitrogenous bases that make up the four nucleotides found in DNA are: 1. Adenine (A) 2. Thymine (T) 3. Cytosine (C) 4. Guanine (G) The base-pairing rule (also known as Chargaff's rules for base pairing) states that: Adenine (A) always pairs with Thymine* (T). Guanine (G) always pairs with Cytosine* (C). These specific pairings ensure the consistent width of the DNA double helix and are crucial for DNA replication and transcription.