Term
| the chromosome theory of inheritance |
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Definition
- mendelian genes have specific loci (positions) on chromosomes
- chromosomes undergo segregation and independent assortment
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Term
| what accounts for mendel's laws of segregation and independent assortment? |
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Definition
| the behavior of chromosomes during meiosis, specifically the crossing over that occurs during prophase I |
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Term
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Definition
| the two alleles for each gene seperate during gamete formation |
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Term
| law of independent assortment |
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Definition
| alleles for genes on a nonhomologous chromosome assort independently during gamete formation. genes on a nonhomolog go wherever they want. |
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Term
| what did thomas hunt morgan discover? |
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Definition
| he found a correlation between a particular trait and an individual's sex. specific genes are carried on specific chromosomes |
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Term
| what organism did morgan observe and experiment on? |
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Definition
| drosophila melanogaster, the fruit fly |
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Term
| why was the fruit fly a convenient organism for genetic study? |
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Definition
- high breeding rate
- genereation can be bred every two weeks, short generation time
- they only have four pairs of chromosomes
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Term
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Definition
| normal phenotypes that are found in nature |
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Term
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Definition
| traits alternative to the wild type |
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Term
| four different methods of sex determination were mentioned what were they? |
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Definition
- XY system
- X0 system
- ZW system
- diploid haploid system
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Term
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Definition
| in grasshoppers, when an individual has two X chromosomes, its female. when it has one X chromosome, its a male |
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Term
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Definition
| when an individual has teh chromosomes ZW its a female, ZZ is a male |
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Term
| explain haplo-diploid system |
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Definition
| when teh individual has a diploid, its a girl, hapliod = dude. example bees |
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Term
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Definition
| gene located on either sex chromosome |
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Term
| what are teh requirements for recessive sex linked traits to be expressed? |
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Definition
a female needs two copies of the allele
a male needs only one copy of teh allele |
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Term
| sex linked recessive disorders in humans are more common in which gender? |
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Definition
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Term
| name three disorders that are caused by recessive alleles on the x chromosome in humans? |
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Definition
- color blindess
- duchenne muscular dystrophy
- hemophilia
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Term
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Definition
| a dense object lying along the inside of the nuclear envelope in the cells of female mammals, representing a higly condensed inactivated X chrmosome. occurs when an X chromosome is deactivated randomly. if the female is heterozygous for a gene located on teh x chromosome, she'll be a mosaic for that character |
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Term
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Definition
| genes located on the same chromosome tha ttend to be inherited together |
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Term
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Definition
| the production of offspring with combinations of traits differeing from either parent |
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Term
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Definition
| offspring with a phenotype matching one of the parental phenotypes |
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Term
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Definition
| offspring with nonparental phenotypes, a new combo of traits or recombinants |
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Term
| who constucted teh genetic map? |
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Definition
| Alfred Sturtevant, a student of morgan |
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Term
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Definition
| an ordered list of genetic loci along a particular chromosome |
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Term
| what was sturtevant's prediction? |
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Definition
| the farther apart two genes are, the higher the probability that a crossover will occur between them and therefore the higher the recombination frequency |
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Term
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Definition
| genetic map of a chromosome based on recombination frequencies |
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Term
| duchenne muscular dystrophy |
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Definition
| disease charcterized by a progressive wekening of the muscles na dloss of coordination |
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Term
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Definition
| disorder define dby the absence of one or more proteins required for blood clotting. |
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Term
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Definition
| distance between genes expressed in centimorgans, representing a 1% recombination frequency. map units indicate relative distance not precise locations |
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Term
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Definition
| indicate positions of genes with respect to chromosomal features |
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Term
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Definition
| pairs of homolous chromosomes that don't deperate normally during meiosis |
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Term
| what are the results of nondisjunction? |
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Definition
| one gamete recives two of the of the same type of chromosome and another gamete receives no copy |
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Term
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Definition
| the result of fertilization of gametes in which nondisjunction occurred. offspring with this condition have an abnormal number of a particular chromosome |
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Term
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Definition
| zygote with only one copy of particular chromosome |
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Term
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Definition
| zygote with three copies of a particular chromosome |
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Term
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Definition
| condition in which an organism has more than two complete sets of chromosomes. common in plants and more normal in appreaance than aneuploids |
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Term
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Definition
| (3n) three sets of chromosomes |
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Term
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Definition
| (4n) is four sets chromosomes |
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Term
| four types of changes in chromosome structure |
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Definition
- deletion
- duplication
- inversion
- translocation
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Term
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Definition
| removes a chromsomal segment |
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Term
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Definition
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Term
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Definition
| reverses a segment within a chromosome |
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Term
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Definition
| moves a segment from one chromosome to another |
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Term
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Definition
| aneuploid condition resulting from three copies of chromosome 21. trisomy 21. frequency increases with age ot he mother, correlation unexplained |
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Term
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Definition
| result of an extra chromosome in a male producing XXY |
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Term
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Definition
| monosomy X produces X0 in females who are sterile and is teh only known viable monosomy in humans |
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Term
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Definition
| cry of the cat, result of deletion of chromosome 5. child is born mentally retareded with a catlike cry and usually die in infancy or early childhood |
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Term
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Definition
| CML, caused by translocations of chromosomes |
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Term
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Definition
| phenotype depending on which parent passed along the alleles for the trait |
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Term
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Definition
| genes that are found in organelles in the cytoplasm |
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Term
| what is the chromosomal theory of inheritance and how was it discovered? |
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Definition
| chromosomal theory says that mendelian genes have specific loci along chromosomes, it is the chromosomes that undergo segregation and independent assortment. it was discovered by morgan while he was studying fruit flies. he found a correlation between sex and a particular trait proving that specific genes carry specific chromosomes (in this case, eye color gene on the x chromosome) |
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Term
| explain why sex linked recessive diseases are more common in human males than females |
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Definition
| sex linked diseses are usually located on teh x chromosome and are recessive. in females both alleles need to be recessive for the trait to be inherited, but males only need one allele |
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Term
| what's the difference between sex linked genes and linked genes? |
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Definition
| sex linked genes are located on teh sex chromosomes. linked genes are genes that are just on the same chromosome and tend to be inherited together in genetic crosses |
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Term
| how does meiosis account for recombinant phenotype? |
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Definition
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Term
| explain how linkage maps are constructed |
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Definition
| the father apart two genes are teh higher the probability that a crossover will occur betwen them and therefore the higher the recombination frequency |
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Term
| how does nondisjunction lead to aneuploidy? |
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Definition
| aneuploids are lacking a chromosome. during nondisjuction a gamete forms wrong yieilding two gamets with an unequal amount of chromosomes |
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Term
| what are teh differences among trisomy, triploidy and polyploidy? |
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Definition
| triploidy has three sets of chromsomes 3n, poly is any somatic cell that has more than two complete sets. trisomy trisomy has 2n + 1 chromosomes |
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Term
| why are extranuclear genes not inhertied in a mendelian fashion? |
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Definition
| extranuclear genes are genes located in organelles in cytoplasm, outside the nucleus. they are not distributed to offspring according to the same rules that direct the distribution of nuclear chrmosomes during meiosis. |
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Term
| name two diseases caused by defects in the mitochondrial genes |
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Definition
| mitochondrial myopathy and leber's heredity optic neuropathy |
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