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Human Genetics

Human Genetics

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Human Genetics

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  1. Human Genetics Concepts and Applications Eighth Edition Powerpoint Lecture Outline Ricki Lewis Prepared by Dubear Kroening University of Wisconsin-Fox Valley

  2. Chapter 1 Overview of Genetics

  3. Genetics • Is a life science • Is the study of inherited variation and traits • Genes are the units of heredity • Genes are composed of Deoxyribonucleic Acid (DNA) • Traits are produced by an interaction between the genes and the environment

  4. Genes • Contain the instructions within the cells for protein production Figure 1.1

  5. TheGenome • Is the complete set of genetic information for an organism • It includes: • All of the genes present in an organism and • Other DNA sequences that do not encode genes • Human genome was sequenced in 2000

  6. Levels of Genetics Figure 1.2

  7. Deoxyribonucleic Acid (DNA) • A double stranded polymer consisting of a chain of nucleotides • Deoxyribonucleotide components: • Phosphate • Sugar: Deoxyribose • Base: • Guanine G Adenine A • Thymine T Cytosine C • The sequence of the bases code for the amino acid sequence in a protein

  8. Reading1.1, Figure 1

  9. Ribonucleic Acid (RNA) • Single stranded polymer of ribonucleotides • Ribonucleotides components: • Phosphate • Sugar: Ribose • Base: • Guanine G Adenine A • Uracil U Cytosine C • Several types • Uses information on DNA to construct proteins

  10. Reading 1.1, Figure 2

  11. Genome • Proteomics – which genes are expressed in cell types • Only 1.5% of the DNA in the human genome encodes protein • Rest includes highly repeated sequences with unknown functions • Includes about 24,000 protein encoding genes • Cataloged in database • Mendelian Inheritance in Man (MIM)

  12. Genes • Alleles are variants of genes • They form by mutation • Mutations in sperm or egg cells are passed on to the next generation • May be positive, negative, or neutral • Examples

  13. Variations • Polymorphisms are variations in the DNA sequence that occur in at least 1% of the population • Single nucleotide polymorphisms (SNPs) are single base sites that differ among individuals and are important as markers

  14. Chromosomes • Composed of DNA and protein • Found in the nucleus of the cell • Human cells have 46 chromosomes • 22 pairs of autosomes • The sex chromosomes X and Y • Females have two X chromosomes • Males have one X and a Y

  15. A Karyotype is a chart of the chromosomes organized by the size of the chromosome pairs. Figure 1.2

  16. Cells • All cells with a nucleus in the body contain the same genetic information • Differentiation causes cells to differ in appearance and function. This is controlled by variation in gene expression. • Stem cells are less specialized and can become many different cell types

  17. Levels of Organization • Cells • Tissues • Organs • Organ systems • Organism Figure 1.3

  18. Individual • The genotype of an individual is the alleles they carry • The phenotype is the visible trait • Dominant alleles are expressed if the individual carries one or two copies of the allele • Recessive alleles are only expressed if the individual carries two copies of the allele

  19. The Family • Inheritance of traits can be observed in families. • A pedigree indicates the structure of a family • schematically. Figure 1.2

  20. A Population • Is a group of interbreeding individuals • The gene pool is the alleles in a population • Evolution is the changing allelic frequencies in populations over time. Figure 1.2

  21. Evolution • Comparison of DNA sequences indicates the amount of similarity between two species. • 98% of human DNA sequences are shared with chimpanzees. • Humans share genes with mice, fish, fruit flies, yeast, and bacteria. Figure1.4

  22. Review of Genetic Terms Table 1.1

  23. Most Genes Do Not Function Alone • Mendelian traits are determined by a single gene • Most traits are multifactorial and not controlled by a single gene. They are influenced by more than one gene and the environment • Some illnesses may occur in different forms: Mendelian, multifactorial, and non- inherited

  24. Genes and Disease Risk • Mendelian traits have simple inheritance • Multifactorial traits more complicated • BRCA1 gene and breast cancer • Ethnic influences as well as environmental • Knowing risk can help us make good choices

  25. Applications of Genetics • Forensics • Identifying victims, DNA at crime scenes, overturning convictions, adoptions • Rewriting history • Thomas Jefferson offspring, the Jewish Lemba • Common ancestory

  26. Figure 1.7

  27. Applications of Genetics Health care • Prediction of disease • Genetic testing, concerns over privacy • Development of treatments • Family planning

  28. Applications of Genetics Agriculture • Biotechnology • Crop and animal breeding • Genetically modified foods

  29. Applications of Genetics • Ecology • Metagenomics – sequencing DNA from a habitat • Sargasso Sea, air samples, human body • Global perspective and human health