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Chapter 10 - BSC 1010 Dr Presley Chapter 10 GENETICS Mendel...

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BSC 1010 Dr. Presley Chapter 10 THE FOUNDATIONS OF GENETICS - 5,000 years ago or more, people were using applied genetics in agriculture - plants provided excellent subjects for research: a) grown in large quantities, b) produced large number of offspring, c) relatively short generation time, d) many had both male and female reproductive organs (monoecious) capable of self-fertilization, e) easy to control matings. - widely held blending theory – once an inheritable trait was combined, this trait could not be separated again, resulting in organisms that are more uniform in the population - Kölreuter – noted contributions for both male and female plant to genetics of plants, used reciprocal crosses - 1866 Gregor Mendel laid the foundation for the science of genetics based on mathematical studies of varieties of peas - Mendel’s work was ignored until 1900 - Time line for CHROMOSOMAL BASIS OF INHERITANCE 1875: cytologists work out details of mitosis 1890: cytologists work out details of meiosis 1902: parallels drawn between genetics and cytology studies GREGOR MENDEL mathematical biologist, quantitative approach to study of nature Augustinian monk, 1843 studied to be a natural science teacher – but failed the teacher’s examination continued his studies of the new mathematics = statistics had no knowledge of “meiosis” or “chromosomes” studied common pea (closed flower) 7 different characteristics (on separate chromosomes) Table10.1, p.190 his experimental plan is shown in Fig. 10.1, p. 188 Study Mendel’s Monohybrid Experiment 1 –Study Figure 10.3 on p. 191 Mendel – proposed the “particulate theory” of heredity (1865) - parents transmit to their offspring inheritable factors (genes) that remain separate factors from one generation to the next. - remember that he had not studied meiosis and did not know about DNA - his work was not accepted, ignored until 1900 TERMS TO KNOW : GENETICS - study of principles of heredity and variation in organisms CHARACTER - in inheritable feature such as flower color, seed shape TRAIT - one of the variant forms of a character expressed in the phenotype - results through the gene control of protein synthesis GENE - a specific portion of a DNA that provides instruction in its base sequence ALLELE - alternative form of gene at a locus on homologous chromosomes LOCUS - position of a gene sequence on a pair of homologous chromosomes Study gene locus for alleles in Fig. 10.5 on page 193 DOMINANT ALLELE - always expressed RECESSIVE ALLELE - not expressed in presence of dominant allele HOMOZYGOUS - possess 2 of the same alleles at locus of homologous chromosomes HETEROZYGOUS - alleles not alike at the locus DIPLOID= has 2 alleles per trait HAPLOID = has 1 allele per trait GENOTYPE - genetic make up, establishes genetic potential of the organism - we will express genotypes by a series of alphabetic letters PHENOTYPE - physical expression of genetic make up - influenced by environment - we will express phenotypes by description of the traits
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Chapter 10 - BSC 1010 Dr Presley Chapter 10 GENETICS Mendel...

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