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| occurs when a single gine affects multiple phenotypic traits |
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| occurs when an allele at one locus affects the phenotype expression of an allele at another locus |
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| phenotype for heterozygotes is intermediate between the the phenotype of the homozygous. |
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| the phenotype of both alles are exhibited in the heterozypte |
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| example is blood type which is determined by three alleles |
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Definition
when multiple genes have an additive affect on a single phenotypic character.
these traits are called complex or quantitative and are usually continuous |
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| occurs when a heterozygote fully expresses one allele, masking the other |
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| the range of phenotypes that result from the an individual's environment |
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| multifactorial characters |
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Definition
| when both environment and genes influence the phenotype of these characters |
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| the way geneticist determine an individual's genotype |
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| a diagram showing the occurence of heritable characters in parents and offspring over generations |
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| how can one get a recessive disorder |
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Definition
| when both parents are carriers or both parents have it. |
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| What are the four example of recessive genetic disorders |
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Definition
| Albinism, Cystic fibrosis, Sickle Cell disease, Tay-Sachs disease |
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| Dominant Allele Disorders |
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Definition
Achondroplasia
Huntington's disease- results in lethal degeneration of the nervous system; starts at 35 to 40 yrs of age
Marfan Syndrome - connective tissue disorder
Polydactyly disease - more than normal number of digits |
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Term
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Definition
| free earlobes, widow's peak, Hair in mid-digits, normal extension of thumb, and left over right thumb cross |
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| Chromosome Theory of Inheritance |
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Definition
current model of inheritance that links genetics to chromosomes:
1.genes have specific loci on chromosomes
2. Alleles at the same locus separate during mieosis, which is mendel's 1st law: law of segregation
3. Alleles on different loci on different chromosomes assort independently from each other, which is Mendel's second law: law of Independent Assortment |
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| the scientist who was skeptical about Mendel's theory and started doing experiments on the drosopphili fly |
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| most common type in population |
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| what is meant by "the sex chromosomes are heteromorphic" |
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Definition
| this means that the X and Y chromosomes have different shapes |
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| Why are recessive sex-linked traits mor often seen in males |
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Definition
| becasue they only need one recessive alleles to show it because they only get one X, but females need two in ordetfor it to show |
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Definition
| phenomenon that explains why females express the sex-linked trait twice as strongly if they have two copies of the sex-linked gene |
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Term
| When a femalk has two copies of a sexlinked gnen |
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Definition
| dense regions of nucleic acis founf only in the somatic cells of women. this form inactivates one X chromosomes leaving women with only one active chromosome |
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Definition
| occurs when an individuals have mxtures of different genetically funtional cells |
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| a phenomenon in which an expression on an allele in an offspring depends on whether the allele in inherited from the male or female parent |
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| scientists that performed an experiment that proved that DNA is the genetic material |
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Definition
Colin MacLeod
Maclyn McCarty
Oswald Avery |
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| Scientists who, in 1952, performed experiemnts that identified DNA as the gentic material of the bacteriophage T2, which infects E. coli and casues the production of new phages. |
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Definition
| Alfred Hershey and Margaret Chase |
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Term
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Definition
| a virus that infects bacteria by injecting somethinginto the bacteria cell |
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