Genes and Chromosomes: Chromosomes are the carriers of genes.
Genes and Enzymes: A gene specifies the amino acid sequence of a polypeptide chain.
Identification of DNA as the Genetic Material: DNA was identified as the genetic material by bacterial transformation experiments.
The Structure of DNA: DNA is a double helix in which hydrogen bonds form between purines and pyrimidines on opposite strands. Because of specific base pairing—A with T and G with C—the two strands of a DNA molecule are complementary in sequence.
Replication of DNA: DNA replicates by semiconservative replication in which the two strands separate and each serves as a template for synthesis of a new progeny strand.
Colinearity of Genes and Proteins: The order of nucleotides in DNA specifies the order of amino acids in proteins.
The Role of Messenger RNA: Messenger RNA functions as an intermediate to convey information from DNA to the ribosomes, where it serves as a template for protein synthesis.
The Genetic Code: Transfer RNAs serve as adaptors between amino acids and mRNA during translation. Each amino acid is specified by a codon consisting of three nucleotides.
RNA Viruses and Reverse Transcription: DNA can be synthesized from RNA templates, as first discovered in retroviruses.
Restriction Endonucleases: Restriction endonucleases cleave specific DNA sequences, yielding defined fragments of DNA molecules.
Generation of Recombinant DNA Molecules: Recombinant DNA molecules consist of a DNA fragment of interest ligated to a vector that is able to replicate independently in an appropriate host cell.
Vectors for Recombinant DNA: A variety of vectors are used to clone different sizes of DNA fragments.
DNA Sequencing: The nucleotide sequences of cloned DNA fragments can be readily determined.
Expression of Cloned Genes: The proteins encoded by cloned genes can be expressed at high levels in either bacteria or eukaryotic cells.
Amplification of DNA by the Polymerase Chain Reaction: PCR allows the amplification and isolation of specific fragments of DNA in vitro, providing a sensitive method for detecting small amounts of specific DNA or RNA molecules.
Nucleic Acid Hybridization: Nucleic acid hybridization allows the detection of specific DNA or RNA sequences by base pairing between complementary strands.
Antibodies as Probes for Proteins: Antibodies are used to detect specific proteins in cells or cell extracts.
Genetic Analysis in Yeasts: The simple genetics and rapid replication of yeasts facilitate the molecular cloning of a gene corresponding to any yeast mutation.
Gene Transfer in Plants and Animals: Cloned genes can be introduced into complex eukaryotic cells and multicellular organisms for functional analysis.
Mutagenesis of Cloned DNAs: In vitro mutagenesis of cloned DNAs is used to study the effect of engineered mutations on gene function.
Introducing Mutations into Cellular Genes: Mutations can be introduced into chromosomal gene copies by homologous recombination with cloned DNA sequences.
Interfering with Cellular Gene Expression: The expression or function of specific genes can be blocked by antisense nucleic acids, RNA interference, or dominant inhibitory mutants.
