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Biology LibreTexts

6: DNA and Protein Synthesis

  • Page ID
    22472
  • This chapter contains information on DNA discovery, the central dogma of biology, DNA replication, transcription, and how proteins are synthesized through the process of translation. Additionally, the chapter highlights gene regulation. This chapter also discusses the types of mutations and their causes. The other topics of this chapter include biotechnology and the Human Genome Project. In order to understand personalized medicine, we need to know what genes do, how they interact, and learn all the differences in DNA between people. As you read this chapter, think about how an understanding of the human genome and genetics is essential for discovering how medicines may affect each of us individually.

    • 6.1: Case Study - Why do we need to sequence everybody's genome?
      Pharmacogenomics is based on a special kind of genetic testing. It looks for small genetic variations that influence a person’s ability to activate and deactivate drugs. Results of the tests can help doctors choose the best drug and most effective dose for a given patient. Many drugs need to be activated by the patient’s own enzymes, and inherited variations in enzymes may affect how quickly or efficiently this happens.
    • 6.2: DNA and RNA
      This young woman has naturally red hair. Why is her hair red instead of some other color? And, in general, what gives her the specific traits she has? There is a molecule in human beings and most other living things that is largely responsible for their traits. The molecule is large and has a spiral structure in eukaryotes. What molecule is it? With these hints, you probably know that the molecule is DNA.
    • 6.3: Chromosomes and Genes
      Chromosomes are coiled structures made of DNA and proteins. They are the form of the genetic material of a cell during cell division. Chromosomes are encoded with genetic instructions for making proteins. These instructions are organized into units called genes. Most genes contain the instructions for a single protein. There may be hundreds or even thousands of genes on a single chromosome.
    • 6.4: Protein Synthesis
      Your DNA, or deoxyribonucleic acid, contains the genes that determine who you are. How can this organic molecule control your characteristics? DNA contains instructions for all the proteins your body makes. Proteins, in turn, determine the structure and function of all your cells. What determines a protein’s structure? It begins with the sequence of amino acids that make up the protein. Instructions for making proteins with the correct sequence of amino acids are encoded in DNA.
    • 6.5: Genetic Code
      The genetic code consists of the sequence of nitrogen bases in a polynucleotide chain of DNA or RNA. The bases are adenine (A), cytosine (C), guanine (G), and thymine (T) (or uracil, U, in RNA). The four bases make up the “letters” of the genetic code. The letters are combined in groups of three to form code “words,” called codons. Each codon stands for (encodes) one amino acid, unless it codes for a start or stop signal. There are 20 common amino acids in proteins.
    • 6.6: Mutations
      Mutations are random changes in the sequence of bases in DNA or RNA. The word mutation may make you think of Ninja Turtles, but that's a misrepresentation of how most mutations work. First of all, everyone has mutations. In fact, most people have dozens or even hundreds of mutations in their DNA. Secondly, from an evolutionary perspective, mutations are essential. They are needed for evolution to occur because they are the ultimate source of all new genetic variation in any species.
    • 6.7: Regulation of Gene Expression
      Using a gene to make a protein is called gene expression. It includes the synthesis of the protein by the processes of transcription of DNA and translation of mRNA. It may also include further processing of the protein after synthesis. Gene expression is regulated to ensure that the correct proteins are made when and where they are needed. Regulation may occur at any point in the expression of a gene.
    • 6.8: Biotechnology
      Biotechnology is the use of technology to change the genetic makeup of living things for human purposes. Generally, the goal of biotechnology is to modify organisms so they are more useful to humans. For example, biotechnology may be used to create crops that yield more food or resist insect pests or viruses, such as the virus-resistant potatoes pictured above. Research is also underway to use biotechnology to cure human genetic disorders with gene therapy.
    • 6.9: The Human Genome
      The human genome refers to all the DNA of the human species. Human DNA consists of 3.3 billion base pairs and is divided into more than 20,000 genes on 23 pairs of chromosomes. The human genome also includes noncoding sequences (e.g. intergenic region) of DNA.
    • 6.10: Case Study Parmacogenomics Conclusion and Chapter Summary
      Steve asked his doctor about Pharmocogenomics. The doctor explains to Steve that Pharmacogenomics is the tailoring of drug treatments to people’s genetic makeup, a form of ‘personalized medicine’.

    Thumbnail: DNA double helix. Image used with permission (public domain; NIH - Genome Research Institute).