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Genetics: A Scientific Revolution

Genetics: A Scientific Revolution. Ohio’s Standards – do not copy.

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Genetics: A Scientific Revolution

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  1. Genetics: A Scientific Revolution

  2. Ohio’s Standards – do not copy • • Life is specified by genomes. Each organism has a genome that contains all of the biological information needed to build and maintain a living example of that organism. The biological information contained in a genome is encoded in its deoxyribonucleic acid (DNA) and is divided into discrete units called genes. • • “Genes are segments of DNA molecules. The sequence of DNA bases in a chromosome determines the sequence of amino acids in a protein. Inserting, deleting or substituting segments of DNA molecules can alter genes. • • An altered gene may be passed on to every cell that develops from it. The resulting features may help, harm or have little or no effect on the offspring’s success in its environments. • • Gene mutations (when they occur in gametes) can be passed on to offspring. • • Genes code for protein. The sequence of DNA bases in a chromosome determines the sequence of amino acids in a protein. • • “The many body cells in an individual can be very different from one another, even though they are all descended from a single cell and thus have essentially identical genetic instructions. Different genes are active in different types of cells, influenced by the cell’s environment and past history.” (AAAS)

  3. Heredity: transmission of traits from parents to offspring Inheritance: genes acquired by offspring

  4. Genetics: study of understanding how characteristics are inherited - Utilizes laws of probability

  5. Gregor Mendel: founder of genetics • Austrian monk • Worked with pea plants and studied how traits were inherited • Tested 15 traits over 28,000 generations • Work was ridiculed initially • Basis for evolution

  6. Alleles: one versions of a gene Ex. • Tall vs. short • Brown eyes vs. blue eyes -Expressed with letters (WW, Ww, Bb)

  7. Gene: segment of DNA that codes for a trait (protein)

  8. Genotype & Phenotype Genotype:the genetic make up of an organism • Expressed in lettered alleles Phenotype: outward characteristics of an organism result of genes

  9. Dominant Allele: the allele whose properties are expresses as phenotype

  10. Recessive Allele: allele whose properties are not observed

  11. Mendel’s 1st ExperimentsMonohybrid Cross 3 Generations: P Generation: pure traits F1 Generation: offspring of P Gen F2 Generation: offspring of F1 Gen -

  12. Law of Segregation: • Traits separate themselves during gamete formation (meiosis) - Dominance, incomplete dominance, sex-linked traits

  13. Dihybrid Crosses: two traits at once

  14. Law of Segregation: traits are inherited independently -frequently violated -genes can be linked (on the same chromosome)

  15. Human Genetics

  16. Discrete Traits • Individual traits • Have or have not • Not many examples in humans

  17. Continuous Traits: -traits on a continuum EX. Human height, nose length, size of feet

  18. Pleiotropy: one gene controlling many traits Ex. Albinism: skin color, visual acuity Phenylketonuria: reduced hair and skin pigment, mental retardation

  19. Epistasis: one gene affects the expression of other genes • May turn off, on; reduce or amplify a trait Ex.

  20. Homozygous: having two identical alleles

  21. Heterozygous: having two different alleles

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