What is a DNA nucleotide? What are its three (3) components?

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.