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Chapter 11: Intro to Genetics

Chapter 11: Intro to Genetics. Work of Gregor Mendel. Who is Gregor Mendel. Gregor Mendel (1822-1884) Austrian Augustinian Monk (Catholic) “Father of Modern Genetics” Worked with pea plants (Why?) Considered true breeding plants Could control their pollination

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Chapter 11: Intro to Genetics

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  1. Chapter 11: Intro to Genetics Work of Gregor Mendel

  2. Who is Gregor Mendel • Gregor Mendel (1822-1884) • Austrian • Augustinian Monk (Catholic) • “Father of Modern Genetics” • Worked with pea plants (Why?) • Considered true breeding plants • Could control their pollination • Design of flower made it safer • Ideas did not catch on right away

  3. What is Genetics? • The study of biological inheritance • What are true breeding plants? • Plants that are self-pollinating • Create specific traits in the plant • Offspring will be identical • What is cross breeding? • Producing plants from different parents • Ex: Crossing a yellow plant and green plant

  4. Genes and Alleles What are genes? Factors that are passed from one parent to offspring Each gene controls a specific trait What are alleles? Variations on a gene Each parents has 2 alleles

  5. What is the Principle of Dominance? • Principle of Dominance • Some alleles are dominant • Some alleles are recessive • When both are present, the dominant allele will always show over the recessive allele • The only time the recessive shows is when no dominant allele is there

  6. What is Segregation? • Segregation • Separating alleles • 25% of all plants showed recessive traits • Recessive traits appear in 2nd generation • Separation of alleles occurred during gamete formation • Gametes: the sperm and egg cells (sex cells)

  7. Chapter 11: Intro to Genetics Applying Mendel’s Principles

  8. Probability • What is Probability? • Likelihood a particular event will happen • All genetics can be determined based off of probability • How does segregation tie into probability? • Each gene has 2 alleles • Homozygous: Both alleles for a gene are the same (TT) • Heterozygous: The alleles for a gene are different (Tt) • This can lead to the difference between genotype and phenotype

  9. What is the difference between genotype and phenotype? • What is phenotype? • The physical traits/characteristics of an organism • This can show if a plant is tall or short (Ex.) • What is genotype? • The genetic makeup of an organism • This shows up as TT or Tt or tt (Letters not traits) • What is the connection between them? • Organisms can have different genotypes but still have the same phenotype • TT and Tt will still produce the same physical trait

  10. Punnett Squares: A way to predict outcome of a genetic cross

  11. What is Independent Assortment? • This is all based off of the idea that one trait can be affected by the alleles for another trait • What he found: • Genes for different traits can segregate independently • These traits have no effect on other traits

  12. Summary of Mendel’s Work • What he learned: • 1. Biological characteristics are inherited through genes which are passed from parent to offspring • 2. A dominant and recessive gene occur when two or more alleles are present • 3. Each adult has two copies of a gene • 4. Alleles for different genes segregate independently

  13. Chapter 11: Intro to Genetics Other Patterns of Inheritance

  14. Co-dominance • The idea that one allele is equal to another • Neither has dominance over the other • Both characteristics will show up in the trait • Cow has both brown and white visible

  15. Incomplete Dominance • Similar to co-dominance • One allele is stronger than the other • However both alleles will show up in the trait • Can be mixed together • White and red colors mix to make pink appear

  16. Multiple Alleles • Appears within a population and not just an individual • Having more than 2 possible alleles for a gene • Allows for multiple dominance • Many different eye colors within a population

  17. Polygenic Traits • Trait controlled by 2 or more genes • Example: Skin color

  18. Chapter 11: Intro to Genetics Meiosis

  19. Chromosome Numbers • Diploid Cells • Human Cells • 2 sets of chromosomes • Designated as “2N” • Haploid Cells • Gametes (Sex Cells) • Sperm and Egg Cells • Designated as “N”

  20. What is Meiosis? • What is meiosis? • Cell division for sex cells • Half the number of chromosome • Allows for fusion during fertilization • Diploid cells are separated which creates the haploid cells • Meiosis can be divided into 2 different stages

  21. Stages of Meiosis I • Prophase I • Copied chromosome matches up with its homologous (identical) chromosome • Tetrads cross over creating new combos

  22. Stages of Meiosis I • Metaphase I • Spindle fibers attach to chromosomes

  23. Stages of Meiosis I • Anaphase I • Chromosomes pull apart to opposite ends

  24. Stages of Meiosis I • Telophase I and Cytokinesis • Nuclear membrane forms • Cell separates into haploid cells

  25. Stages of Meiosis II • Prophase II • 2 Connected daughter cells are created

  26. Stages of Meiosis II • Metaphase II • Chromosomes line up

  27. Stages of Meiosis II • Anaphase II • Separate and move to end of the cell

  28. Stages of Meiosis II • Telophase II and Cytokinesis • Nuclear membrane forms • 4 haploid cells created

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