Part 3 Summary.docx - 1 MENDELIAN GENETICS TERMINOLOGY Gene...

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1. MENDELIAN GENETICSTERMINOLOGYGeneControls physical character of an individualInherited from parents via gametesSequence on chromosomes that makes RNA which make proteinsAlleleAlternate forms of a gene (not all allelic changes result in phenotypic changesE.g. components of blood groups such as A, B, OLocusSite of a specific gene of DNA sequence on a chromosomeIrrespective of whether the locus is a region that is genic or not (locus can be a marker as long as it is a unique sequence on the chromosome)GenotypeIndividual’s collection of genesThe allele combinations in an individual that cause a particular trait or disorder (for diploid organism, e.g. blood group AA, AO, AB, etc) PhenotypeTrait’s visible appearance (e.g. eye colour/height)Physical expression of genotype (not visible) (e.g. a particular protein form, blood group)HomozygotePerson having 2 identical alleles at a particular locus on homologous chromosome (e.g. blood groups AA, BB, OO)HeterozygotePerson possessing different alleles at a particular locus on homologous chromosomes (e.g. blood group AO, AB, BO)HemizygoteDescribes the genotype of males with an X-linked trait, as males only have one X chromosomeDominant TraitAn allele that is expressed when present in even one copy (e.g. blood group A, B)Recessive TraitAn allele whose expression is masked by another alleleChromosomeStructure (a molecule) within a cell nucleus that carries genesA chromosome consists of a continuous molecule of DNA and proteins wrapped around itAutosomeA non-sex-determining chromosome (humans have 22 pairs)Sex chromosomeA chromosome containing genes that specify sex (human male XY, human female XX)1.1. MENDELSLAWS1.1.1. EXPERIMENTS BY MENDEL (EXPERIMENTAL SPECIES: GARDEN PEA PSIUM SATIVUM)1.Species was available in several varieties with well-defined characteristics 2.Pea plants have modified petal known as keel, which covers the reproductive structures of plant, enabling reproduction by self-fertilisation; cross fertilisationalso possible3.Pure-bred(homozygous) varieties wereavailable4.Flower hermaphroditic having male andfemale parts5.Relatively short life cycle6.Large number of offspringproduced from eachmating7.“model” organism chosen to mimic nature oforganisms (or rep humans because wecan’t use humans) criteria =homology like humans; but with advantages likeshort life cycles for faster expt etcStudy of 7 characteristics that bred trueoTrue-breedingline = a variety thatdoes not vary in appearance from generation to generation after several generations of self-fertilisationoMendel studied these characteristics by crossing the variants to each other in monohybrid cross (aka single factor cross)produces monohybrids
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Data and interpretation1.Mendel’s data argued strongly against blending mechanismof heredity (in al 7 cases, F1generation displayedcharacteristics that were distinctly like one of the two parents rather than traits intermediate in character) 1st

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