1. Chapter 1 The Science of Genetics © John Wiley & Sons, Inc.

2. Chapter Outline  Three Great Milestones in Genetics  DNA as the Genetic Material  Genetics and Evolution  Levels of Genetic Analysis  Genetics in the World: Applications of Genetics to Human Endeavors © John Wiley & Sons, Inc.

3. Three Great Milestones in Genetics  Gregor Mendel: Genes and the rules of inheritance  James Watson and Francis Crick: the structure of DNA  The Human Genome Project: sequencing DNA and cataloguing genes © John Wiley & Sons, Inc.

4. Mendel: Genes and the Rules of Inheritance (1866)  Genes—hereditary factors responsible for traits  Alleles —different forms (versions) of hereditary factors (genes)  Traits —A physical characteristic brought about by the expression of a gene or many genes.  Rules of Inheritance –Alleles of the same gene separate during gamete formation –Alleles of different genes are inherited independently © John Wiley & Sons, Inc.

5. Gene:DNA sequence (fragment) that holds the information for a trait Trait: a notable feature or quality in an individual that makes us unique Allele:an alternative form (versions) of a gene (one of a pair) that occupy a specific position on a specific chromosome. Variation among non-coding DNA sequences.

6. Locus (plural loci): specific location of a gene (DNA sequence ) on a chromosome Chromosome: nucleoprotein structure observed during cell division Mitosis: One (single) cell division producing two identical daughter cells Meiosis: Two cell divisions resulting in 4 cells NOT genetically identical

7. What is a Gene?  Genes are made of nucleic acids  Nucleic acids are made of building blocks called nucleotides  Nucleotides have three components –Sugar molecule (ribose or deoxyribose) –Phosphate molecule –Nitrogen-containing molecule (adenine-A-, guanine-G-, cytosine- C-, thymine-T-, uracil-U-)  RNA is ribonucleic acid  DNA is deoxyribonucleic acid © John Wiley & Sons, Inc. (OH) !!!! Splicing reaction

8. The Structure of a Nucleotide Nucleoside Nucleotide

9. Watson and Crick: The Structure of DNA (1953)  Nucleotides are linked in a chain through sugar-phosphate interactions  DNA molecules are made of two chains of nucleotides wound around each other in a helix  Base pairs hold the chains together –A pairs with T –G pairs with C © John Wiley & Sons, Inc. ( Rosalind Franklin)

10. The Human Genome Project: Sequencing DNA and Cataloguing Genes  Genome—the collection of DNA molecules that is characteristic of an organism  Genomics is the analysis of DNA sequences that make up a genome  Genomics involves DNA sequencing technology, robotics, and computer science  The Human Genome Project determined the sequence of nucleotides in the DNA of the human genome © John Wiley & Sons, Inc.

11. DNA as the Genetic Material  Information flows from DNA to RNA to protein (Central Dogma).  In all cellular organisms, the genetic material is DNA.  The genetic material –Must be able to replicate –Must contain information –Must be able to change © John Wiley & Sons, Inc.

12. The Central Dogma of Molecular Biology  The flow of information is DNA  RNA  protein. © John Wiley & Sons, Inc.

13. DNA Replication (duplication) © John Wiley & Sons, Inc.

14. DNA Replication  Based on the complementary ( anti-parallel) nature of the two strands of duplex DNA molecules.  When the two parental strands are separated, the separated strands can serve as template for the synthesis of new strands.  New strands are assembled by incorporating nucleotides according to base-pairing rules.  At the end of replication, each template strand is paired with a newly synthesized partner strand.  DNA replication is catalyzed by enzymes. © John Wiley & Sons, Inc.

15. Gene Expression: Using Genetic Information © John Wiley & Sons, Inc.

16. Gene Expression  During transcription, an RNA molecule is synthesized from a DNA template.  This messenger RNA (mRNA) molecules contains the information needed to synthesize a polypeptide.  During translation, the triplet codons in the RNA specify the incorporation of particular amino acids into a polypeptide chain. © John Wiley & Sons, Inc.

17. Proteome/Genome  Proteome/Genome—the collection of all the different proteins (genes) in an organism.  Humans have between 20,000 and 25,000 genes in the genome and hundreds of thousands to millions of proteins in the proteome.  Proteomics/Genomics—the study of all the proteins (genes) in cells. © John Wiley & Sons, Inc.

18. The Central Dogma of Molecular Biology  The flow of information is DNA  RNA  protein.  Some viruses can use RNA as a template for the synthesis of DNA in reverse transcription ( Human?).  Many genes do not encode polypeptides; their end-products are RNA molecules (microRNA and piRNA) © John Wiley & Sons, Inc.

19. Telomeres The end of each chromosome is called a telomere and is distinguished by a set of repeated sequences. New repeats are added by a telomerase, a reverse transcriptase that synthesizes DNA from a RNA template. Telomeres are required for the complete replication of the chromosome because they protect the ends from being degraded. Telomerase activity: “ is thought to have major effects on cell life ”

20. Mutation: Changing Genetic Information © John Wiley & Sons, Inc.

21. Genetics and Evolution  Variation in the DNA sequence makes it possible for species to evolve over time.  Organisms with similar DNA sequences are descended from a common ancestor. © John Wiley & Sons, Inc.

22. A phylogenetic tree  A phylogenetic tree, or phylogeny, represents the historical relationships among organisms. © John Wiley & Sons, Inc.

23.  Evolution depends on the occurrence, transmission, and spread of mutant genes in groups of organisms.  DNA sequence data provide a way of studying the historical process of evolution. © John Wiley & Sons, Inc.

24. Levels of Genetic Analysis © John Wiley & Sons, Inc. Geneticists approach their science from different points of view—from that of a gene, a DNA molecule, or a population of organisms.

25. Classical Genetics  Based on analysis of the outcomes of crosses between different strains of organisms.  Can be coordinated with studies of the structure and behaviour of chromosomes. © John Wiley & Sons, Inc.

26. Molecular Genetics  Studies the replication, expression, and mutation of genes at the molecular level.  Rooted in the study of DNA sequences and the manipulation of DNA molecules. © John Wiley & Sons, Inc.

27. Population Genetics  Individuals within a population may carry different alleles of genes.  Population genetics is based on analyzing allele frequencies in a population and determining whether these frequencies changes over time.  Population genetics includes evolution and the inheritance of complex traits. © John Wiley & Sons, Inc.

28. Genetics in the World: © John Wiley & Sons, Inc. Genetics is relevant in many venues outside the research laboratory.

29. Genetics in Agriculture: Selective Breeding © John Wiley & Sons, Inc.

30. Genetics in Agriculture: Genetically Modified Organisms  Genetically Modified Organisms (GMOs) are have been altered by the introduction of foreign resistance genes. © John Wiley & Sons, Inc.

31. Genetics in Medicine  Inborn Errors of Metabolism are metabolic abnormalities caused to mutant alleles.  Molecular genetics –new ways to detect mutant alleles (BRCA1). –new ways to treat diseases. © John Wiley & Sons, Inc.

32. Genetics in Society  Economic impact—biotechnology industry, pharmaceutical industry.  Legal impact—paternity testing, forensics, identification  Can you patent a gene sequence?  Can you patent a natural product? © John Wiley & Sons, Inc.