1 / 24

GENETICS

GENETICS. Mendel and the Gene Idea. Genetics. The study of heredity . Gregor Mendel (1860’s) discovered the fundamental principles of genetics by breeding garden peas. He Used Plants that looked like this:. True Breeding Plants: consistently have offspring with same

sloane-nixon
Download Presentation

GENETICS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. GENETICS

  2. Mendel and the Gene Idea

  3. Genetics • The study of heredity. • Gregor Mendel (1860’s) discovered the fundamental principles of genetics by breedinggarden peas.

  4. He Used Plants that looked like this: True Breeding Plants: consistently have offspring with same trait as parent.

  5. Genetics • Alleles 1. Alternative forms ofgenes. 2. Units that determine heritable traits.

  6. Dominant Alleles Dominant alleles (TT - tall pea plants) a. homozygous dominant Homozygous = two alleles that are the same.

  7. Recessive Alleles Recessive alleles (tt - dwarf pea plants) a. homozygous recessive Homozygous = two of the same alleles Recessive = Hidden allele when dominant is present.

  8. Mixed Alleles Heterozygous (Tt - tall pea plants) Mixed set of alleles. Dominant takes over for physical trait (phenotype).

  9. Phenotype • Outward appearance • Physical characteristics • Examples: 1. tall pea plant 2. dwarf pea plant

  10. Genotype • Arrangement of genes that produces the phenotype • Example: 1. tall pea plant TT = tall (homozygous dominant) 2. dwarf pea plant tt = dwarf (homozygous recessive) 3. tall pea plant Tt = tall (heterozygous)

  11. Punnett square • A Punnett square is used to show the possible combinations of gametes.

  12. T T t t Showing a cross with Pea Plants • tall (TT) vs. dwarf (tt) pea plants

  13. T T produces the 1st generation Tt Tt t Tt Tt t All Tt = tall (heterozygous tall) tall (TT) vs. dwarf (tt) pea plants

  14. T t T t Cross the 1st generation • tall (Tt) vs. tall (Tt) pea plants

  15. T t produces the 2nd generation Tt TT T 1/4 (25%) = TT 1/2 (50%) = Tt 1/4 (25%) = tt Tt tt t 1:2:1 genotype 3:1 phenotype tall (Tt) vs. tall (Tt) pea plants

  16. Monohybrid Cross • Mendel did A breeding experiment that tracks the inheritance of a single trait.

  17. Segregation Principle of Segregation The principle of segregation is explained by the behavior of homologous chromosomes at meiosis.

  18. Law of Independent Assortment • Genes for different traits are separated and distributed to gametes (sex cells) independently of one another

  19. Incomplete Dominance • This is when both alleles contribute to the phenotype of a heterozygous individual to produce a trait that is not exactly like either parents. • Ex: A flower has genes for white petals (W) and red petals (R). When you mix white flowers with red flowers you get pink flowers.

  20. Codominance • Two dominant alleles are expressed at the same time. • The human ABO blood group illustrates another genetic phenomenon – codominance. • The AB phenotype (genotype IA and IB is an example.

  21. Height is a polygenic trait Polygenic Inheritance – When a Single Trait is Influenced by Many Genes

  22. Multiple Alleles • Many genes are present in 3 or more versions (alleles) – this is known as multiple alleles. • The human ABO blood group is determined by three alleles (IA, IB, and i) of a single gene.

  23. Pleiotropy – When One Allele Influences Many Traits

  24. Sex-Linked Traits • Traits carried on sex chromosomes X or Y • Ex: Red green color blindness, Hemophilia

More Related