2.1.3 DNA Double Helix

• The DNA double helix is a spiral-shaped structure composed of two polynucleotide strands.
• The two polynucleotide strands in the DNA double helix are parallel to each other.

  False
• What are the three components of a DNA nucleotide?

  Phosphate, sugar, base
• Match the nitrogenous base pairs with the number of hydrogen bonds between them:

  Adenine (A) - Thymine (T) ↔️ 2

  Guanine (G) - Cytosine (C) ↔️ 3
• What is the relationship between adenine and thymine in DNA according to Chargaff's rules?

  A equals T
• The two polynucleotide strands in the DNA double helix are arranged in an anti-parallel manner.
• What are the three components of a DNA nucleotide?

  Phosphate group, deoxyribose sugar, nitrogenous base
• A 5-carbon sugar in the DNA nucleotide is called deoxyribose
• Nitrogenous bases in DNA form complementary pairs that determine genetic information.
• Match the DNA component with its description:

  Phosphate Group ↔️ Forms the backbone of DNA

  Deoxyribose Sugar ↔️ A 5-carbon sugar

  Nitrogenous Bases ↔️ Determine genetic information
• What do Chargaff's rules state about the base composition of DNA?

  A = T, G = C</latex>
• Adenine (A) pairs with Thymine (T) using two hydrogen bonds.
• How many hydrogen bonds are formed between Guanine (G) and Cytosine (C)?

  Three
• Hydrogen bonds between complementary base pairs hold DNA strands together.
• Match the base pair with the number of hydrogen bonds:

  A-T ↔️ 2

  G-C ↔️ 3
• Non-covalent forces between adjacent base pairs in DNA are called stacking interactions.
• What are the two polynucleotide strands in the DNA double helix called?

  Anti-parallel
• The DNA double helix has a pitch of 3.4 nanometers per turn.
• The DNA double helix is held together by hydrogen bonds between complementary base pairs.
• How many hydrogen bonds are formed between Adenine (A) and Thymine (T)?

  Two
• Guanine (G) forms three hydrogen bonds with Cytosine (C).
• What type of sugar is found in a DNA nucleotide?

  Deoxyribose
• Each DNA nucleotide consists of a phosphate group, deoxyribose sugar, and a nitrogenous base.
• Arrange the structural features of the DNA double helix in order of their contribution to stability:

  1️⃣ Hydrogen Bonds

  2️⃣ Stacking Interactions

  3️⃣ Anti-Parallel Arrangement

  4️⃣ Specific Dimensions
• What is the arrangement of the two polynucleotide strands in the DNA double helix called?

  Anti-parallel arrangement
• Hydrogen bonds in the DNA double helix are formed between complementary base pairs A-T and G-C.
• What type of interactions between adjacent base pairs contribute to the stability of the DNA double helix?

  Stacking interactions
• The DNA double helix is approximately 2 nm wide.
• Steps involved in the process of DNA replication

  1️⃣ Unwinding the double helix

  2️⃣ Complementary base pairing

  3️⃣ Joining of new nucleotides

  4️⃣ Proofreading
• Hydrogen bonds and stacking interactions contribute to the stability of the DNA double helix.
• Why is complementary base pairing essential during DNA replication?

  Ensures accurate duplication
• The sequence of bases in DNA determines the genetic information transcribed into RNA.
• What is the equation representing the helical structure of the DNA double helix?

  $\text{Helical Structure} =$$2 \times \text{Polynucleotide Strands} +$$\text{Hydrogen Bonds} +$$\text{Base Pair Complementarity}$