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Unformatted text preview: Bio Exam 3 3/11/08 Gregor Mendel pages 251-255- BORN 1822- Monk at the monastery of St. Thomas in Brunn, Czech Republic- Trained in Botany- 1866 published his work Experiments with Palnt Hybrids- 1900 Mendels work was redsiscovered by Hugo de Vries in Holland, Carl Correns in Germany and Erich vox Tschermak in Austrua- particulate rather than blending Mendel worked with edible pea plants- there was John Goss- English 1824 worked with the same plants30 years before Mendel began his work- He observed green and yellow seeds in peas followed time through a number of generations- He observed what Mendel saw Today we speak of Medelian genetic not Gossian- why- Goss didnt record and count number of seeds Why did Mendel succeed?- he chose the right organism to work with, the edible pea plant o the plant self pollinates, ie self fertilizes o stigma and anthers are completely enclosed by petals until after fertilization o therefore there is no cross contamination Figure 14.2- he picked the right traits to follow- simple single gene inheritance- he followed the crosses for several generations- he was quantitative in his observations (counted and recorded)- he had help from his friends Figure 14.3, table 14.1 Definitions/Terminology- Gene discrete unit of hereditary information consisting of a specific sequence of DNA. It often codes for a polypeptide chain (a sequence of amino acids) Gene locus- a particular position along a specific chromosome where a given gene is located Allele- alternative from of a gene- A,a- B,b- Sometimes superscript or lower case letter (Genetics Problems- on blackboard under assignments- a guide to the kinds of questions youll have to answer on the third exam Homozygous- having 2 identical alleles for a trait- AA- Aa- Two superscript big As or big Bs- ii Heterozygous- having two different genes (alleles) for a trait- Aa- Superscript AB- S.s. Ai- S.s Bi Figure 14.4 Genotype- refers to the genetic make up of an individual Phenotype- the physical manifestation of a trait o how it appears- determined by the genotype HOW MANY DIFF ALLELES CAN A DIPLOID INDIVIDUAL HAVE AT A SINGLE GENE LOCUS IF THERE ARE 4 ALLELES IN A POPULATION? 2 Dominant Allele- allele that is fully expressed in the phenotype of a heterozygote- only a single copy is required to express the trait- represented by the capital letter (A) Recessive Allele- in a heterozygous individual the allele that is completely masked (not expressed) in the phenotype- rep by lower case letter (a) Why is it not expressed?...
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This note was uploaded on 08/22/2010 for the course BIOL 1201 taught by Professor Wishtichusen during the Spring '07 term at LSU.
- Spring '07