DNA Structure and Function Quiz

DNA Structure

Double Helix Model

• Formulated by James Watson and Francis Crick in 1953.
• Structure consists of two intertwined strands forming a right-handed helix.
• The backbone is composed of alternating sugar (deoxyribose) and phosphate groups.
• The strands run in opposite directions (antiparallel) – one runs 5' to 3', the other 3' to 5'.
• The interior of the helix contains nitrogenous bases that pair specifically.

Nucleotide Composition

• DNA is made up of four nucleotides, each composed of three components:
  • Phosphate group
  • Deoxyribose sugar
  • Nitrogenous base (one of four types)
• The four nitrogenous bases include:
  • Adenine (A)
  • Thymine (T)
  • Cytosine (C)
  • Guanine (G)
• Nucleotides link together through covalent bonds between the phosphate of one nucleotide and the sugar of another.

Base Pairing Rules

• Specific pairing between nitrogenous bases is critical for DNA structure:
  • Adenine (A) pairs with Thymine (T) via two hydrogen bonds.
  • Cytosine (C) pairs with Guanine (G) via three hydrogen bonds.
• This complementary base pairing is essential for DNA replication and transcription.
• The arrangement of base pairs allows for the encoding of genetic information.

DNA Structure

• The double helix structure of DNA was discovered in 1953 by James Watson and Francis Crick.
• The DNA double helix is composed of two intertwined strands arranged in a right-handed spiral.
• Each strand is made up of a backbone of alternating deoxyribose sugar and phosphate groups.
• The strands run in opposite directions, one running from 5' to 3' and the other from 3' to 5', known as antiparallel.
• The inside of the helix contains nitrogenous bases held together by hydrogen bonds.
• Each nucleotide consists of a phosphate group, a deoxyribose sugar, and a nitrogenous base.
• There are four nitrogenous bases in DNA:
  • Adenine (A)
  • Thymine (T)
  • Cytosine (C)
  • Guanine (G)
• Adenine (A) always pairs with Thymine (T), forming two hydrogen bonds.
• Cytosine (C) always pairs with Guanine (G), forming three hydrogen bonds.
• These complementary base pairs are crucial for DNA replication and transcription.
• The specific sequence of base pairs in DNA carries the genetic information.

Test your knowledge on the DNA double helix model, nucleotide composition, and base pairing rules. This quiz covers the fundamental aspects of DNA structure as formulated by Watson and Crick. Perfect for students looking to solidify their understanding of molecular biology.