Overview of Genetics

1. Overview of Genetics Ch. 1

2. Genetics • Is the study of inherited traits and their variation • Is a life science that should not be confused with genealogy • Is also an informational science that is having a huge societal impact Figure 1.1

3. Genes • Contain the instructions within the cells for protein production • Genes are composed of deoxyribonucleic acid (DNA) • Traits are produced by an interaction between the genes and their environment Figure 1.1

4. The Genome • Is the complete set of genetic information for an organism • It includes all of the genes present in an organism • And also DNA sequences that do not encode genes • Genomics is a field that analyzes and compares genomes of different species

6. Levels of Genetics

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

8. Box, Figure 1 Reading1.1, Figure 1

9. Ribonucleic Acid (RNA) • A single stranded polymer of ribonucleotides • Ribonucleotide components: - Phosphate - Sugar: Ribose - Base: Adenine A Guanine G Uracil U Cytosine C • Exists in several types • Uses information on DNA to construct proteins

10. Box, Figure 2 Reading 1.1, Figure 2

11. The Human Genome • Only 1.5% of our DNA encodes protein - About 20,325 protein-encoding genes in all • Rest of the human genome includes highly repeated sequences with unknown functions • Genes known to cause disorders or traits are cataloged in a database - Online Mendelian Inheritance in Man (OMIM) • Proteomics is a field that studies the proteins made in a cell

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

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 - Can cause disease or act as genomic markers

14. Research • Genome-wide association studies track SNP patterns among individuals who share a particular trait or disorder • Gene expression profiling measures which genes are more or less active in particular cell types

15. Chromosomes • Composed of DNA and protein • Found in the nucleus of the cell • Human somatic cells have 46 chromosomes - 22 pairs of autosomes - A pair of sex chromosomes - Females have two X chromosomes - Males have one X & a Y

16. Karyotype A chart displaying the chromosome pairs from largest to smallest Figure 1.2 Figure 1.2

17. Cells • A human body contains approximately 50-100 trillion cells - All cells except RBCs contain the same genome • Differentiation causes cells to differ in appearance and function - Controlled by variation in gene expression • Stem cells are less specialized and can become many different cell types

18. Individual The genotypeof an individual refers to the alleles they carry The phenotype is the visible trait A dominant allele is expressed if the individual carries just one copy A recessive allele is only expressed if the individual carries two copies

19. The Family Individuals are genetically connected into families A pedigree is a diagram used to study traits in families - Can be used to trace multiple genes or genes with large environmental component - Will be discussed in detail in Chapter 4

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

21. Evolution Genome comparisons among species reveals evolutionary relationships - The more similar the sequences are, the more recent the divergence from a common ancestor 98% of human DNA sequences are shared with chimpanzees Humans share genes with mice, pufferfish, fruit flies, yeast, and even bacteria

22. Figure 1.4 Figure1.4

23. Mendelian vs. Multifactorial Traits Mendelian traits are determined by a single gene - Their recurrence is predicted based on Mendel’s laws Multifactorial traits are determined by one or more genes and the environment - Predicting their recurrence is much more difficult Most traits are multifactorial

24. Mendelian vs. Multifactorial Traits Figure 1.5

25. Genes and Disease Risk • Genetic determinism is the idea that the expression of an inherited trait is inevitable • This may be harmful or helpful, depending on its application - As part of a social policy, it is disastrous - Knowing genetic risks can help us make good choices

26. Applications of Genetics Genetics impacts many areas of our lives DNA profiling (DNA fingerprinting) looks at SNPs and short repeated DNA sequences - It has applications in: - Forensics - History and ancestry

27. Forensics Identification of victims of natural disasters or terrorist attacks Matching the DNA of suspects to samples left at the crime scene Helping adopted individuals locate blood relatives

29. History and Ancestry DNA analysis can flesh out historical details - Revealing the offspring of Thomas Jefferson and Sally Hemmings - Revealing the origins of the Jewish Lemba of South Africa

30. History and Ancestry Figure 1.6 Figure 1.7 Figure 1.7

31. Health Care Pharmacogenomics is a field that identifies individual drug reactions based on genetics

32. Health Care Analysis of single-gene illnesses reveals many differences from other diseases

33. Health Care Diseases are increasingly being described in terms of gene expression patterns Tracking gene expression can reveal new information about diseases and show how diseases are related to each other - This is not obvious via traditional medicine

34. Genetic Testing and Treatment Tests to identify about 1,200 single-gene disorders have been available for years - Direct-to-consumer (DTC) genetic testing The Genetic Information Non-discrimination (GINA) act was passed in the US in 2008 Genome information is useful for developing treatment to genetic and infectious diseases

35. Gene therapy attempts to correct certain genetic disorders.

36. Agriculture Traditional agriculture is the controlled breeding of plants and animals Biotechnology is the use of organisms or their parts to produce goods and services Genetically-modified (GM) organisms have new genes or over- or under-express their own genes

37. Transgenic rice manufactures beta-carotene and stores twice as much iron as unaltered rice. A transgenic organism harbors a gene or genes from a different species. These animals make glowing fluorescent protein (gene from a jellyfish) Goats produce spider silk protein in their milk

38. A Global Perspective Genetics and genomics are spawning technologies that may vastly improve the quality of life Human genome information has tremendous potential for the entire globe - Individual nations are using approaches that exploit their particular strengths

39. A Global Perspective