Genetics. Genetics – branch of biology that deals with patterns of inheritance, or heredity. Heredity- biological process by which parents pass on genetic.
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Genetics – branch of biology that deals with patterns of inheritance, or heredity. Heredity- biological process by which parents pass on genetic information to their offspring through their gametes An Austrian monk, Gregor Mendel, is said to be the “father of genetics” because he performed series of experiments on pea plants in the mid 1800’s.
Principles of Mendelian Genetics No knowledge of genes and chromosomes Careful observations of the inheritance pattern of specific traits found in pea plants (mathematical analysis of large numbers of offspring) Concluded- traits controlled by pairs of inherited ‘factors’ with one member of each pair coming from each parent organism.
Major concepts P (parent generation) Organisms that are used to begin studies F 1 (first filial generation) Offspring produced by crossing members of parent generation F 2 (second filial generation) Offspring crossed between members of the F 1 generation
Major concepts Mendel’s Principle of Dominance Ex: cross peas that were pure for contrasting traits; pure tall with pure short. All offspring showed only one of the two contrasting traits. All were tall. Dominant- allele that is expressed – (capital letter) Recessive- allele not expressed (lower case of same letter) http://www.teachersdomain.org/resources/hew06/sci/life/gen/dominantgene/index.html
Homozygous -two genes of a pair of alleles are the same (aka pure) TT or tt Homozygous dominant TT Homozygous recessive tt Heterozygous- two genes of a pair of alleles are different (aka hybrid) Tt Genotype- The genetic makeup of organism- TT, Tt, tt Phenotype- Physical appearance of an organism that results from its genetic makeup. TT & Tt tall, tt short
Punnett Square Diagram that shows possible offspring of genetic cross.
Mendel’s Law of Segregation (video) http://www.teachersdomain.org/resources/hew06/sci/life/gen/mendelinherit/index.html
Segregation and Recombination When gametes are formed during meiosis, the two chromosomes of each homologous pair separate, or segregate randomly. Each gamete contains only one allele for each trait. After gametes fuse during fertilization, the resulting zygote cell contains pairs of homologous chromosomes, but new combination for alleles may be present. Ex: Principle of Segregation.