Bio Notes for Third Test

Bio Notes for Third Test - Bio Notes for Third Test Gregor...

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Bio Notes for Third Test Gregor Mendel – Pages 251-255 - Born 1822 - Monk at the monastery of St. Thomas in Brunn, Czech Republic - Trained in botany, mathematics and physics at the University - In 1866 published his work “experiments with Plant Hybrids” - 1900 Mendel’s work was rediscovered by Hugo de Vries I Holland, Carl Correns in Germany and Erich von Tschermak in Austria - “ Particulate rather than blending Worked with edible pea plants There was a long history of previous work on peas Why did Mendel succeed and others not? John Goss - English in 1824 worked with the same plants 30 years before Mendel began his worl - He observed green and yellow seeds in peas followed them through a number og generations - He observed what Medel Saw Today we speak of Mendelian genetics not Gossian Genetics Why?- Goss did not record the number of seeds Why did Mendel succeed? - He chose the right organism to work with, the edible pea plant. - The plant usually self pollinates, i.e., self fertilizes - Stigma and anthers are completely enclosed by petals until after fertilization
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- Therefore there is no cross contamination - He picked the “right” traits to follow – simple single gene inheritance - He followed the crosses for several generations - He was quantitative in his observations - He had a little help from his friends Definitions/ terminology Gene - Discrete unit of hereditary information consisting of a specific sequence of DNA - Often codes for a polypeptide chain Gene locus - A particular position along a specific chromosome where a given gene is located Allele - Alternative form of a gene - E.g. A, a or B, b - Sometimes indicated with superscript or lowercase letter Genetic problems - On blackboard - A guide to the kinds of questions you’ll have to answer on the third exam - Has file with answers Homozygous - Refers to having 2 identical alleles for a trait - AA - aa - superscripted Heterozygous
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- having two different genes (alleles) for a trait - Aa - Ia Ib superscripted Genotype - The genetic makeup of an individual Phenotype - The physical manifestation of a trait- how it appears - Determined by the genotype How many different alleles can a diploid individual have at a single gene locus if there are 4 alleles in the population? TWO Dominant allele - Allele that is fully expressed in the phenotype of heterozygote - Only a single copy is required to express the trait - Represented by a capital letter Recessive allele - In a heterozygous individual the allele that is completely masked ( not expressed ) in the phenotype - Represented by lower case letter (a) Why is it not expressed? - Inactive or defective enzyme Generations - P – parental - F1 – Filial one – offspring of the parental generation – hybrids - F2 – offspring of cross between F1 (hybrid) individuals Punnett Square- four boxes, top represents gametes of parents, fig 14.5
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Medel’s first Law - The two members of a gene pair separate from each other into the gametes - Each gamete carries one member of the gene pair
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This note was uploaded on 04/19/2008 for the course BIOL 1201 taught by Professor Wishtichusen during the Spring '07 term at LSU.

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Bio Notes for Third Test - Bio Notes for Third Test Gregor...

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