Nucleic Acids

• What is DNA, and why is it important?

  DNA (Deoxyribonucleic Acid) is the hereditary material in all living organisms. It stores genetic information required for growth, development, and reproduction.
• What are the key differences between DNA and RNA?

  • DNA: Deoxyribose sugar, double-stranded, thymine instead of uracil.
  • RNA: Ribose sugar, single-stranded, uracil instead of thymine.
• What does it mean that DNA strands are antiparallel?

  DNA strands run in opposite directions: one runs 5' to 3', and the other runs 3' to 5'. This arrangement is critical for replication
• • What are the three components of a nucleotide?

  1. Phosphate group (circle).
  2. Pentose sugar (pentagon; deoxyribose in DNA, ribose in RNA).
  3. Nitrogenous base (rectangle; A, T, C, G in DNA or A, U, C, G in RNA).
• • Which nitrogenous bases are purines, and which are pyrimidines?
  • Purines (double-ring): Adenine (A), Guanine (G).
  • Pyrimidines (single-ring): Cytosine (C), Thymine (T), Uracil (U in RNA).
• • How do nitrogenous bases pair in DNA and RNA?
  • DNA: A pairs with T (2 hydrogen bonds), C pairs with G (3 hydrogen bonds).
  • RNA: A pairs with U, C pairs with G.
• • How is the sugar-phosphate backbone formed, and why is it important?

  Covalent bonds between the phosphate group of one nucleotide and the sugar of another create the backbone, which provides stability and structure to DNA.
• What role do hydrogen bonds play in DNA structure?

  Hydrogen bonds between complementary bases hold the two strands of DNA together, providing stability while allowing strand separation during replication or transcription.
• • Why is complementary base pairing important?

  It ensures accurate replication and transcription by matching A with T (or U in RNA) and C with G.
• • Describe the structure of the DNA double helix.

  DNA consists of two antiparallel strands twisted into a double helix, with a sugar-phosphate backbone on the outside and nitrogenous bases paired on the inside.
• What are the main roles of DNA in cells?

  1. Long-term storage of genetic information.
  2. Template for replication and transcription.
  3. Provides instructions for protein synthesis.
• • Why is the genetic code considered universal?

  The same codons specify the same amino acids in almost all organisms, providing evidence for common ancestry.
• • How does DNA replicate accurately?

  DNA replication relies on complementary base pairing. Each strand serves as a template for a new strand, ensuring accurate duplication of genetic information.
• What emergent properties arise from the polymerization of DNA and RNA?

  • Ability to store and transmit genetic information.
  • Replication fidelity through complementary base pairing.
  • Catalytic activity (in RNA, e.g., ribozymes).
• • What is polymerization, and how does it relate to DNA and RNA?

  Polymerization is the process of linking nucleotides to form long chains of DNA or RNA. It occurs via condensation reactions that remove water molecules
• • Why is RNA thought to be the first genetic material?

  RNA can act as both genetic material and a catalyst (e.g., ribozymes), supporting the RNA world hypothesis.
• • How does sequence variability in DNA contribute to diversity?

  The limitless combinations of base sequences allow immense genetic diversity, enabling evolution and adaptation.
• List 3 structural differences between DNA and RNA.

  • DNA has thymine, RNA has uracil.
  • DNA is double-stranded, RNA is single-stranded.
  • DNA contains deoxyribose, RNA contains ribose.
• What are the three types of RNA and their roles?

  • mRNA: Carries genetic information to ribosomes.
  • tRNA: Transfers amino acids during translation.
  • rRNA: Catalyzes peptide bond formation in ribosomes
• How does the sugar in nucleotides affect DNA and RNA?

  • Deoxyribose in DNA makes it more stable for long-term storage.
  • Ribose in RNA makes it more reactive for short-term processes
• • How do hydrophilic and hydrophobic properties influence DNA?

  The sugar-phosphate backbone is hydrophilic, allowing DNA to interact with water, while the nitrogenous bases are hydrophobic, stabilizing the internal structure.
• • How does the universal genetic code enable genetic engineering?

  Genes from one organism can be expressed in another (e.g., inserting human insulin genes into bacteria).
• • Why do purines pair with pyrimidines?

  Purines (A, G) are larger molecules, and pairing with smaller pyrimidines (T, C, U) maintains uniform DNA width.
• • What makes DNA more stable than RNA?

  DNA’s double-stranded structure and deoxyribose sugar make it less reactive and more stable than RNA.