1 / 24

Genetics

Genetics. Gregor Mendel. Genetic Concepts. Phenotype Physical characteristics of organism Result of gene expression Biochemical properties of proteins determine physical characteristics of organism Genotype Set of alleles present in genome of organism Alleles are versions of genes.

moana
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. Gregor Mendel

  3. Genetic Concepts • Phenotype • Physical characteristics of organism • Result of gene expression • Biochemical properties of proteins determine physical characteristics of organism • Genotype • Set of alleles present in genome of organism • Alleles are versions of genes

  4. Segregating Traits in Sweet Pea

  5. Genetic Crosses • Monohybrid • cross between two variants of a single trait • ABO type A x ABO type B • Dihybrid • cross between two variants of two traits • ABO type A, Rh+ x ABO type B, Rh-

  6. Mendel’s Monohybrid Crosses Pea Color Trait Generation G Y P x F1 All Yellow x ¼ of progeny green F2

  7. What Does It Mean, Mendel??? • The disappearance of the green trait in F1 means it is recessive • The appearance of only the yellow trait in F1 means it is dominant • A recessive trait is seen if only recessive alleles of that gene are present • The dominant trait is seen if 1 or 2 alleles of that gene are present • THERE MUST BE TWO ALLELES OF EACH GENE • THE ALLELES SEPARATE DURING REPRODUCTION

  8. Mendel’s Dyhybrid Crosses Pea Color Trait & Height Trait Generation Y G P x All Yellow & Tall F1 x

  9. Mendel’s Dihybrid Cross 9/16 yellow & tall 3/16 green & tall 3/16 yellow & short 1/16 green & short F2

  10. What Does It Mean, Mendel??? • Yellow and Tall are dominant traits; green & short are recessive • EITHER ALLELE CONTROLLING COLOR CAN ASSORT WITH EITHER ALLELE CONTROLLING HEIGHT

  11. Mendel’s Principles • Law of Segregation • There are two alleles (distinct copies) of each gene in the genome of an organism • The two alleles are separated during meiosis and put into separate gametes • Law of Independent Assortment • Any allele of one gene may assort with any allele of any other gene • All possible allelic combinations are possible if enough gametes are produced

  12. Chromosomes & Genes Homologous Chromosomes Sister Chromatids Maternal Homolog Paternal Homolog Loci Alleles Non-Sister Chromatids

  13. Meiosis I

  14. Crossing Over (Not with John Edward) y Y z Z

  15. Meiosis II

  16. Inheritance Patterns • Complete Dominance • Co-dominance • Intermediate Dominance

  17. Complete Dominance/Recessiveness Phenotype: ABO type A Genotype: IAIA, IAO Phenotype: ABO type B Genotype: IBIB, IBO Phenotype: ABO type O Genotype: OO

  18. Co-Dominance • Phenotype: ABO type A • Genotype: IAIB • Both A & B alleles encode functional enzymes • Both enzymes work at same time • Both modifications are made simultaneously • Phenotype is combined effect of both A & B enzymes

  19. Intermediate Dominance • A dosage effect • B better than B’ • BB > BB’ > B’B’ • Red, pink, white flowers • RR > RW > WW

  20. Linkage • Genes on same chromosome are separated by crossing over during meiosis I • Genes located near each other, on the same chromosome, are separated infrequently • Often they are inherited together • This is termed “being linked”

  21. Chromosomal Sex Determination • In most organisms, males & females have a unique pair of chromosomes which determine sex • XY mechanism • Males – XY; females - XX • ZW mechanism • Males – ZZ; females - ZW • X0 mechanism • Males – X_ ; females - XX

  22. Sex Linkage Normal • Genes on the X or Y chromosomes are sex-linked • A phenotype caused by a gene on the X chromosome will appear in males more frequently Normal

  23. DNA

  24. Complementary Base Pairing

More Related