5.biological inheritance
- 2. GENETIC INHERITANCE Mendel (XIX century) demonstrated that hereditary characteristics are determined by independent factors which are transmitted from generation to generation. Chromosomes are the carriers of genetic information. Mendel independent factors are fragments of DNA that determine the characteristic of a specific trait.
- 3. BASIC CONCEPTS GENE: Unit of DNA that transmit genetic information ALLELE: Each variant of a gene GENOTYPE: Set of genes that an individual has FENOTYPE: Observable traits that an individual has
- 4. HOMOZIGOUS: both alleles are the same HETEROZIGOUS: both alleles are different Dominant allele prevent the alternative gene (recessive allele) from appearing
- 5. When both alleles are equally strong are called co-dominant and cause intermediate inheritance
- 6. MENDEL’S LAWS Mendel discovered the basic principles of heredity by breeding garden peas in carefully planned experiments Mendel chose a plant whose varieties displayed “pure” traits, which had been selected long before and which remained constant from generation to generation, making them easy to identify. He used a self-pollinating plant. The petals enclose the stamens and the pistil completely, which means that the plant crosses with itself, so accidental crossing with different plants is avoided, and pure strains can be obtained.
- 7. Traits studied by Mendel
- 8. Principle of uniformity (1st law)
- 9. Principle of segregation (2nd law)
- 10. Principle of independent assortment (3rd law)
- 11. Test cross The additional experiment which Mendel carried out, to prove that alleles come in pairs and separate at the moment when gametes form, consisted of crossing F1 (yellow seeds) with the pure paternal line of green seeds (recessive homozygote). Let’s take the yellow seed to be Aa. Green seed Semilla verde Yellow amarilla Semilla seed F1 F1 Aa x a aa a A In this case, 50% green seeds and 50% yellow seeds are obtained. If the yellow seed had been AA, all of the seeds would have been yellow (Aa). Aa Aa aa aa a
- 12. Watch the video
- 19. LINKED GENES
- 22. EXERCISE
- 23. DETERMINING SEX
- 24. A single gene determines sex
- 25. ZZ/ZW
- 30. GENE MUTATIONS