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PG 30-32 GENETICS

PG 30-32 GENETICS. NOTES AND VOCABULARY. Genetics - the study of heredity . Heredity - a set of characteristics received from parents. Raising useful plants and animals . Prevention and treatment of diseases . Discovering the secrets of life on Earth. Solving crimes .

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PG 30-32 GENETICS

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  1. PG 30-32GENETICS NOTES AND VOCABULARY

  2. Genetics - the study of heredity. • Heredity - a set of characteristics received from parents.

  3. Raising useful plants and animals. • Prevention and treatment of diseases. • Discovering the secrets of life on Earth. • Solving crimes. USES FOR GENETICS

  4. Known as the “father of genetics.” • Was both religious and scientific. • Introduced this branch of science to the world by cross-breeding plants, studying traits being passed along, and producing hybrids. Gregor Mendel

  5. Mendelian inheritance does not take account of recombination or mutation. DIFFERENCE BETWEEN MENDELIAN GENETICS AND NON-MENDELIAN GENETICS

  6. True-breeding (purebred) - an organism with parents having the same traits. • Hybrid - an organism with parents having different traits. • Genes - parts of chromosomes that “carry” traits. • Alleles - different forms of a gene. DEFINITIONS

  7. Dominant - an allele that excludes the recessive form. • Recessive - an allele that is not expressed in the presence of a dominant allele. • AA - HOMOZYGOUS DOMINANT (same big) • Aa - HETEROZYGOUS (AKA: CARRIER - an organism that “carries” a recessive gene that is not expressed.) (different alleles) • aa - HOMOZYGOUS RECESSIVE (same small) ALLELES

  8. Phenotype - displays the physical form of a trait. • Only what you can see when you look at an organism. • Genotype - displays the genetic form of a trait. • Only what the genes express…you may not be able to tell. What is the difference between phenotype and genotype?

  9. Punnett Square - a process used to determine the probability of offspring traits. • Probability - studies the likelihood of occurrence of random events. • Monohybrid - comparing one trait in a Punnett square. • Dihybrid - comparing two traits in a Punnett square. PUNNETT SQUARES

  10. Multiple alleles - a type of gene that is determined by more than 2 alleles. • Complete dominance - a heterozygous condition in which both alleles are partially expressed. This results in an intermediate phenotype. • Incomplete dominance - a form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a combined phenotype. • Codominance - a condition in which both alleles of a gene pair in a heterozygote are fully expressed, with neither one being dominant or recessive to the other. MORE DEFINITIONS

  11. Polygenic traits - traits for which the phenotype (appearance) depends on alleles in multiple genes. • Sex-linked traits - traits associated with a gene that is carried only by the male or female parent. • DNA fingerprinting - a technique to distinguish between individuals of the same species using only samples of their DNA. LAST DEFINITIONS!!!

  12. BLOOD TYPING CHART

  13. Three Conclusions to His Research • Principle of Dominance and Recessiveness One allele in a pair may mask the effect of the other • Principle of Segregation The two alleles for a characteristic separate during the formation of eggs and sperm • Principle of Independent Assortment The alleles for different characteristics are distributed to reproductive cells independently.

  14. Mendelian genetics • Character (heritable feature, i.e., fur color) • Trait (variant for a character, i.e., brown) • True-bred (all offspring of same variety) • Hybridization (crossing of 2 different true-breds) • P generation (parents) • F1 generation (first filial generation) • F2 generation (second filial generation) • Testcross: breeding of a recessive homozygote X dominate phenotype (but unknown genotype)

  15. How can the Chances of an Offspring’s Traits be Determined? • BY USING A PUNNETT SQUARE • Get out your Guinea Pig Dihybrid Cross • I will call up students to fill in one square on the example dihybrid cross on the board until we complete the problem.

  16. What about 2 Traits? • BbLl x BbLl • The Gametes contain one of each of the alleles. (BL). • Each of the offspring contain four alleles exactly like the parents.(BbLl). • Notice the number of possible offspring has increased. • The phenotypic ratio is 9:3:3:1

  17. BbLl x BbLl

  18. Now on your own… Work the Dihybrid Crosses on your own.

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