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Understanding Genetics: Mendel's Laws, Traits, and Genetic Manipulation

Learn about Gregor Mendel's laws of inheritance, dominant and recessive traits, and genetic manipulation techniques such as selective breeding and recombinant DNA. Explore the concept of trisomy and its implications in human genetic conditions.

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Understanding Genetics: Mendel's Laws, Traits, and Genetic Manipulation

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  1. Genetics Def: the study of reproduction and the results of the combination of chromosomes. Gregor Mendel – (1822 – 1884) Austrian Monk who is considered “Father of Genetics” Mendel’s Laws 1. Law of Segregation - Chromosomes separate (segregate) into different gametes during meiosis. 2. Law of Independent Assortment All Chromosomes segregate independent of each other. None are connected to each other. Seed shape & Seed color are inherited independently of each other. YyRr: GametesYR, Yr, yR, yr

  2. Mendel talked about traits and called the genes for those traits alleles. Allele - the different genes for a trait The traits that you got when sperm and egg came together was NOTHING but probability. A roll of the dice or a flip of a coin

  3. Mendel also gave us the genetics terms Dominant and Recessive If both traits are present in a Genotype and one is expressed over the other Dominant - Having a homozygous rec. Genotype is the only way a recessive trait can be expressed is to be (both parents must carry the trait) Recessive - Example: Your Mom gives you the gene for having a Unibrow (recessive) and your father gives you the gene for having two eye brows (dominant) What are you? Mom Dad

  4. Let’s look at some traits DOMINANT Black color This dog’s genetics could be two ways We show it like this: “B” from one parent, “B” from the other parent OR “B” from one parent, “b” from the other parent “BB” is Homozygous Dom. for the trait. Recessive lighter color “Bb” is Heterozygous for the trait. This dog’s genetics CAN ONLY be shown one way: “b”from one parent, “b”from the other parent Recessive traits are ALWAYShomozygous rec.; thus it would be “bb”

  5. OK, now for a problem: If I have a heterozygous black male and a golden female that mate, X what is the chances of having golden puppies in the litter? b b B b 50% black 50% golden 100% golden You can make a Punnett square b b Bb Bb 50% B bb bb b

  6. What do we do if we want to predict the offspring with two traits? • Dihybrid Cross: tool used to predict the offspring of parents with TWO traits YyRr x YyRr -Determine the gametes -Show the cross • Ex:

  7. Definitions to know: Genotype: what the genes say (heterozygous or homozygous). Phenotype: physical appearance of the organism (black or golden). P Generation: the parents in the problem F1 Generation: the first “filial” – child, first generation after the parents. F2 Generation: the second generation after the parents.

  8. Everything is not always clear cut: Incomplete Dominance: One allele can not completely dominate the other. Codominance: When both dominant alleles show in the offspring. Red White Roan offspring

  9. Multiple Allele Traits: Example: Traits having more than one allele that can be found in the population. Human Blood Types Type A, Type B, Type AB, Type O Four distinctly different types Polygenic Traits: Example: Traits that are controlled by several genes at the same time. Human hair color Black, BrownBlonde &Red Four major colors blended through more than a dozen different allele groups.

  10. Genetic Engineering Definition: manipulating the genes of an organism due to selective breeding or microbiological processes Selective Breeding: selecting certain individuals to be the parents of the future generations. All of these things are products of selective breeding

  11. Hybridization: Crossing two “wild” species to try to get a hybrid with the best traits of the parent species. Hybrid Vigor: Having an offspring species that is better in many ways than either of the parent species

  12. Chromosomes You have two for each “pair”. One from Mom, and one from Dad Mom Dad But what happens if there are three for a “pair”? The situation is called Trisomy: Having three chromosomes for a pair of chromosomes.

  13. Some Trisomy situations: Trisomy 21 (Down syndrome) Trisomy 18 (Edwards syndrome) Trisomy 13 (Patau syndrome) Trisomy 8(Warkany syndrome 2) Of these, Trisomy 21 and 18 are the most common. Both cause delayed growth, mental issues, and physical limitations. How can a Doctor know if a person has a specific Trisomy situation?

  14. Karyotyping: This involves catching the chromosomes when they are compacted ready for cell division. Then they must be paired up with their “match” When all the chromosomes in the human genetic makeup are paired, it looks like this: For simplicity, geneticist only use one half of each of the Chromosome to do the matching. Each half is a Chromatid

  15. Genetic Manipulation: Recombinant DNA: The process of manipulating a gene by taking genes from one organism and moving them to another. Step 1– Isolation of target gene. Lets say that there is a gene in this corn that is drought resistant. enzymes Researchers use enzymes to isolate and cut the gene out (excise) from the original corn. Target Gene

  16. Step 2- Copy the gene Using a machine called a PCR (polymerase chain reaction), the geneticist make thousands of copies of the gene Step 3– Insertion of gene Using enzymes again, the geneticist inserts the gene into the genetic code of the target plant. Step 4– Testing of results Field Biologists set out plots to test the drought resistance of the new plants.

  17. Organisms that have the genes of other organisms are called: Transgenic organisms Examples: Transgenic Yeast cells Produces human insulin Drought-resistant Barley Can live in little water and some in salty water environments Herbicide resistant and Pest Resistant Corn Plants that will not die when weeds around them are sprayed, and some species that pests do not want to eat

  18. Cloning Target sheep Donor sheep nucleus Process: Take a cell from your organism and an egg from a donor female. Take the nucleus from the donor egg. Fuse the two cells by electro-shock. Introduce the right hormones to begin division becoming an embryo. Implant the embryo into the donor female. Embryo The cloned organism is born.

  19. Review for Genetics Test Define: • Genetics 2. Gregor Mendel 3. Allele • 4. Dominant 5. Recessive 6. Homozygous pairs • 7. Heterozygous pairs 8. Genotype 9. Phenotype • 10. P Generation 11. F2 Generation 12. F1 Generation • 13. Incomplete Dominance 14. Co-dominance • 15. Multiple Allele Trait 16. Polygenic Trait 17. Monosomy • 18 Polysomy 19. Hybrid vigor 20 Genetic engineering • 21. Hybridization 22. cloning 23. recombinant DNA Questions: • What are the two “laws” that are attributed to Mendel? • How do they affect genetics?

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