Genetics and inheritance
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This document summarizes key concepts in genetics and inheritance, including Mendel's experiments with pea plants, his laws of segregation and independent assortment, genetic crosses, and degrees of dominance. It discusses how Mendel used pea plants to discover the basic principles of heredity, including that alleles segregate independently and each organism inherits one allele for each trait from each parent. The summary also outlines the concepts of complete, incomplete, and codominance.
Genetics and inheritance
- 1. LIFE SCIENCES GRADE 12 UNIT 5 GENETICS AND INHERITANCE By Vilakazi N.S 216010009
- 2. THE PROCESS OF HYBRIDIZATION Genetics: the study of heredity Heredity: relations between successive generations. Gregory Mendel was the father of genetics. Mendel discovered the basic principles of heredity by breeding garden peas in carefully planned experiments. Advantages of pea plants for genetic study: Cross-pollination (fertilization between different plants) can be achieved by dusting one plant with pollen from another. True breeding : breeding varieties of organisms with only one variety of type.
- 3. LAW OF SEGREGATION P-generation – true breeding parents F1-generation- hybrid offspring of the P-generation F2-generation- hybrid offspring of the F1 generation Alleles-alternative versions of a gene Locus- position of a gene in a chromosome Homozygous- identical alleles e.g(BB) Heterozygous- different alleles e.g(Bb)
- 4. LAW OF INDEPENDENT ASSORTMENT Two alleles for a heritable character separate during gamete formation and end up in different gametes.
- 5. GENETIC CROSSES Each pair of alleles segregate independently of each other pair of alleles during gamete formation. (applies to different non-homologous chromosomes) Genotype-genetic composition of a gene Phenotype- physical appearance of a gene
- 6. DEGREES OF DOMINANCE 1. MONOHYBRID CROSS-cross between 2 organisms where we look at one pair of contrasting traits.(determine outcome of F1 generation) 2. DIHYBRID CROSS- cross between 2 organisms where we look at two pairs of contrasting traits at the same time.
- 7. SUMMARY OF GENETICS Complete dominance One allele suppresses the expression of the other allele. Incomplete dominance: phenotype of F1 hybrids is somewhere between the phenotypes of the 2 parental varieties – neither allele completely dominant (White x Red = Pink) Codominance, 2 dominant alleles affect the phenotype in separate, distinguishable ways. (Red and white flowers = White and red visible.)
- 8. REFERENCES Chromosomes carry hereditary info (genes) Chromosomes (and genes) occur in pairs New combinations of genes occur in sexual reproduction Monohybrid vs. Dihybrid crosses Mendel’s Principles: Dominance: one allele masks another Segregation: genes become separated in gamete formation Independent Assortment: Members of one gene pair segregate independently from other gene pairs during gamete formation ADDITIONAL RESOURCES https://www.youtube.com/watch?v=ya7h-Y-9l8c https://www.youtube.com/watch?v=bVk0twJYL6Y
- 9. Hartwell, L. (2010). Genetics: From Genes to Genomes 4th Edition. McGraw Hill. London. Available from slide share: https://www.slideshare.net/rspawar007/genetics-70106620 Assessed: 13 December 2016