Chapter 10

Molecular Biology of the Gene - Key Concepts

• Measles Overview

  • Caused by a contagious virus characterized by a red rash.

  • Nearly eradicated in the U.S. until outbreaks, like in California (2014).

  • Understanding of nucleic acids (DNA & RNA) is crucial for combating viruses.

• Big Ideas in Genetic Material

  • Structure of genetic material

  • DNA replication

  • Flow of genetic information from DNA to RNA to protein

  • Genetics of viruses and bacteria

• Scientific Experiments

  • Frederick Griffith (1928): Discovered transformation in bacteria; genetic material was inherited.

  • Hershey and Chase: Showed DNA is genetic material using phages; injected DNA in bacteria leads to new phages.

• Nucleotides Structure

  • DNA & RNA are polymers of nucleotides, which comprise:

  • Nitrogenous base

  • Five-carbon sugar

  • Phosphate group

  • DNA contains adenine (A), cytosine (C), thymine (T), and guanine (G).

  • RNA contains uracil (U) instead of thymine and ribose instead of deoxyribose.

• DNA Structure

  • Double-helix model proposed by Watson and Crick, featuring complementary base pairing (A-T, G-C).

  • DNA replication is semiconservative; each old strand serves as a template for a new strand.

• Flow of Genetic Information

  • Transcription: DNA is used to synthesize RNA.

  • Translation: RNA is translated into proteins.

  • Genetic code composed of codons (triplet codes) translates nucleotide sequence into amino acids.

• Mutations

  • Changes in genetic information can occur due to errors during replication or by physical/chemical mutagens.

• Viruses

  • Consist of nucleic acid in a protein coat.

  • Can enter lytic (active replication) or lysogenic (integration into host DNA) cycles.

  • Emerging viruses (e.g., HIV, Coronavirus) pose health threats.

• Prions

  • Infectious proteins causing diseases by inducing misfolding of normal proteins.

• Key Understanding Goals

  • Summarize Griffith’s, Hershey’s, and Chase’s experiments on DNA as genetic material.

  • Distinguish structures of DNA and RNA.

  • Explain DNA structure's role in replication.

  • Outline the DNA replication process.