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38 Cards in this Set
- Front
- Back
Genotype
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actualgenetic make up of an individual.
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dominant
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expressionthat is alwaysexpressed if its gene is present in the genotype.
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Recessive
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expressionthat is expressed onlywhenits allele is the only form of the gene present in the genotype.
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incompletedominance
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Neitherallele is dominant to the other, thus each is expressed in theheterozygous genotype producing an intermediate phenotype. EX. Red(RR) and White (R’R’) snapdragons produce pink (RR’).
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Epistasis
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Acondition in which one gene pair has theability to mask or prevent the expression of another gene pair. EX.Coat color and pigment deposition in mice
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Co-dominance
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inheritancecharacterized by full expression of both alleles in the heterozygote.
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homozygous |
conditionwhere both members of a pair of gene are the same (ex. AA or aa ) |
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heterozygous |
conditionin where two expressions of a gene pair are different (ex. Aa) |
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alleles |
differentforms of the same gene. |
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locus |
locationof the gene on the chromosome. |
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gene-
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Theunit of DNA along a chromosome that codes for a singlecharacteristic (Mendelian definition) or the unit of DNA thatcodes for a specific polypeptide (molecular definition).
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synapsis |
Pairingof homologous chromosomes |
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cross-over |
Theexchange or mixing of similar genetic |
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chiasmata |
criss-crossingof the non-sister chromatids |
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karyotype |
displayof metaphase chromosomes where homologs are paired together andphotographed. |
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pleiotrophy |
Theability of a single gene pair to have multiple effects. EX. Gene for Sickle-cell Anemia. |
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sexchromosomes |
chromosomesinvolved in sex determination. in males they're the X and Ychromosomes.
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polygenicinheritance |
Acharacteristic that isdetermined by the quantitative effect of multiple pairof genes. |
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Duplication |
Inthis situation a portion of a chromosomebreaks and attaches to its homologue, thus those genes arerepresented twice on the chromosome carrying the duplicated segment. Having an abnormal number of genes is often lethal in animals. |
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Translocation |
n a portion of a chromosomebreaks and rejoins with a non- homologous chromosome. This type ofabnormality can result in an increased number of genes in a gamete orcan impact coordination of a metabolic path |
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deletion |
Aportion of a chromosome is lost fromthe genome, thus these genes are not present in the gamete. The loseof genes from the genotype is serious and often lethal. |
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Inversion |
inan inversion a section of a chromosomebreaks and rejoins with the same chromosome, but in a reversedorder. The proper sequence of genes is often important in thecoordination of metabolic pathways. If the inversion affects such apathway then it can have a serious impact. |
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linkedgenes |
Refersto genes located on the same chromosome;Linked genes do not normally assort independentofeach other. Linked genes usually assort together. Independentassortment of chromosomes and unlinkedgenes. |
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autosomes |
chromosomesnot involved in sex determination although they may carry genes forsecondary sexual characteristic. |
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independentassortment of homologous chromosomes |
statesthat the members of one pair of homologous chromosomes segregateindependent of all other homologous pair during gamete formation. |
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Genotype
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actualgenetic make up of an individual.
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Phenotype |
actualexpression of a characteristic. |
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Characteristic |
heritablefeature such as flower color. |
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trait |
variationsof a character such as white or purple flowers. |
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truebreeding |
plantsself pollinate,offspring are identicle to parents |
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hybrid
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matingof individuals with different expressions of a character
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lawof segregation-
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statesthat the members of a gene pair separate during gamete formation meaning that each gamete receives only one gene from each pairduring meiosis.
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testcross
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crossbetween an individual expressing a dominant phenotype with anindividual expressing the recessive expression of the same character
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ruleof addition
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Theprobability of an event that can occur in two or more ways is the sumof the separate probabilities of the different ways. EX. Parents areboth heterozygous for a given characteristic "Aa". What isthe probability of their having a child that is also "Aa"? The probability of the "A" allele being in the egg and "a"in the sperm is 1/2 X 1/2 = 1/4. The probability of the "a"allele being in the egg and the "A" in the sperm is 1/2 X1/2 = 1/4. Thus the probability of an "Aa" child is 1/4 +1/4 = 1/2.
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rule of multiplication
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The probability that independent events will occur simultaneously is the product of their individual probabilities. EX. The probability of giving birth to a daughter is 1/2 at any one birth. The probability of three consecutive daughters being born to a couple is 1/2 X 1/2 X 1/2 = 1/8.
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multiple alleles
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In this type of inheritance there are more than two alleles for the same characteristic in the general population, although any one individual only has two genes for the characteristic. EX. ABO blood group.
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Pedigrees
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Family history for a particular trait.Shows the relationship of parents to children over many generations.
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Barr body
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Condensed inactivated X chromosome.
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