Introduction to Genetics

1. Introduction to Genetics • Definition of “Genetics” • Proteins • Nucleic Acids • The Central Dogma of Genetics • Historical Perspective

2. A. Definition of “Genetics” • Genetics: Understanding how information for protein structure is transmitted, structured, and expressed • Transmission of genetic information during reproductive processes: Heredity • Structure of genetic information • Expression of genetic information

3. B. Proteins • General properties • Composed of chains of amino acids • There are 20 different amino acids, each with distinctive chemical properties • A protein molecule may contain several hundred amino acids • Each different protein has its own order, or “sequence,” of amino acids • The correct sequence of amino acids is essential for the protein’s function

4. B. Proteins • Functions • Enzymes: enzymes are biological catalysts that control almost every reaction in living systems • Cellular recognition and communication • Structural components of living cells

5. B. Proteins • Levels of protein structure • Primary structure: amino acid sequence • Secondary structure: localized folding of a chain into regions of helix or sheet structure • Tertiary structure: folding of a single polypeptide chain into a three-dimensional structure • Quaternary structure: only in proteins with more than one polypeptide chain; Folding of more than one chain together

6. C. Nucleic Acids • General properties • Composed of chains of nucleotides • There are 4 different nucleotides • A nucleic acid molecule may contain several thousands or millions of nucleotides • Each nucleic acid molecule has its own order, or “sequence,” of nucleotides • The correct sequence of nucleotides is essential for the nucleic acid’s function

7. C. Nucleic Acids • Overall function. • The sequence of nucleotides in a nucleic acid molecule serves as a blueprint to encode the correct sequence of amino acids for a protein. The code for a specific protein is called a “gene.” • Deoxyribonucleic acid (DNA): DNA molecules (chromosomes) serve as the “master blueprint” for all of the cell’s proteins. The DNA molecules are transmitted to offspring during reproduction. • Ribonucleic acid (RNA): RNA molecules serve as “working copies” of the genes for the proteins that the cell is making at any given time.

8. D. Central Dogma of Genetics • DNA replication • Transcription • Translation

9. E. Historical Perspective • Early ideas • Preformation vs. Epigenesis • Dispersive Information vs. Germ Plasm • Mid-1800s – Early 1900s: • Discovery and re-discovery of transmission genetics • Early 1900s – Mid 1900s: • Discovery of the structure of the genetic information • Mid 1900s – Early 2000s: • Mechanisms of genetic expression and regulation • Development of molecular genetics technology