9 Questions
What is the approximate diameter of the DNA molecule according to the double helix model?
2 nanometers
What are the two components of the sugar-phosphate backbone of the polynucleotide chain?
Sugar molecules and phosphate groups
What is the function of the phosphate groups in the sugar-phosphate backbone?
They give the backbone a negative charge
What is the composition of a nucleotide?
A sugar molecule, a phosphate group, and a nitrogenous base
According to the base pairing rules, which base pairs with Thymine (T)?
Adenine (A)
What is the function of the phosphodiester bonds in the polynucleotide chain?
They link nucleotides together
What type of bond is formed between the 3' hydroxyl group of one nucleotide and the 5' phosphate group of another?
Phosphodiester bond
What is the approximate pitch of the double helix structure?
3.4 nanometers
What is the characteristic shape of the double helix model of DNA?
A right-handed spiral staircase-like structure
Study Notes
Polynucleotide Chain Structure
Double Helix Model
- The double helix model describes the 3D structure of DNA
- Two complementary polynucleotide chains twisted together
- Chiral, with a right-handed spiral staircase-like structure
- Diameter: approximately 2 nanometers (nm)
- Pitch: approximately 3.4 nm (10 base pairs)
Sugar-Phosphate Backbone
- The backbone of the polynucleotide chain is composed of:
- Sugar molecules (deoxyribose in DNA)
- Phosphate groups
- The sugar and phosphate molecules alternate in a repeating pattern
- The backbone is negatively charged due to the phosphate groups
Nucleotide Composition
- A nucleotide is composed of:
- A 5-carbon sugar (deoxyribose in DNA)
- A phosphate group
- A nitrogenous base (A, C, G, or T)
- Nucleotides are linked together through phosphodiester bonds
Base Pairing Rules
- Adenine (A) pairs with Thymine (T) through two hydrogen bonds
- Guanine (G) pairs with Cytosine (C) through three hydrogen bonds
- Base pairing is complementary, with each base having a specific partner
- Base pairing is responsible for the stability of the double helix structure
Phosphodiester Bonds
- Phosphodiester bonds link nucleotides together in a polynucleotide chain
- Formed through a condensation reaction between the 3' hydroxyl group of one nucleotide and the 5' phosphate group of another
- Phosphodiester bonds are strong covalent bonds that hold the backbone together
Learn about the double helix model of DNA, the sugar-phosphate backbone, nucleotide composition, base pairing rules, and phosphodiester bonds. Understand the structure and composition of DNA molecules.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
