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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.