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| The idea that genetic material contributed by both parents mixes in a manner analogous to the way blue and yellow paints blend to make green paint |
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| A heritable feature that varies among individuals |
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| Each variant for a character |
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| A true-breeding plant is one that, when self-fertilized, only produces offspring with the same traits. The alleles for these type of plants are homozygous. |
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| refers to having identical alleles for a single trait (YY or yy) |
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| The mating or crossing, of two true breeding varieties |
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| The true breeding parents |
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| Offspring of the P generation |
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| The offspring of the self pollinated F1 generation |
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Definition
Mendel's law of segregation states that allele pairs separate or segregate during gamete formation, and randomly unite at fertilization. There are four main concepts involved in this idea. They are:
1. There are alternative forms for genes. This means that a gene can
exist in more than one form. For example, the gene that determines pod color
can either be (G) for green pod color or (g) for yellow pod color.
2. For each characteristic or trait organisms inherit two alternative forms
of that gene, one from each parent. These alternative forms of a gene are
called alleles.
The F1 plants in Mendel's experiment each received one allele from the green
pod parent plant and one allele from the yellow pod parent plant. True-breeding
green pod plants have (GG) alleles for pod color, true-breeding yellow pod
plants have (gg) alleles, and the resulting F1 plants have (Gg) alleles.
3. When gametes (sex cells) are produced, allele pairs
separate or segregate leaving them with a single allele for each trait.
This means that sex cells contain only half the compliment of genes. When
gametes join during fertilization the resulting offspring contain two sets of
alleles, one allele from each parent. For example, the sex cell for the green
pod plant had a single (G) allele and the sex cell for the yellow pod plant had
a single (g) allele. After fertilization the resulting F1 plants had two alleles
(Gg).
4. When the two alleles of a pair are different, one is dominant and the
other is recessive. This means that one trait is expressed or shown, while
the other is hidden. For example, the F1 plants (Gg) were all green because the
allele for green pod color (G) was dominant over the allele for yellow pod
color (g). When the F1 plants were allowed to self-pollinate, 1/4 of the F2
generation plant pods were yellow. This trait had been masked because it is
recessive. The alleles for green pod color are (GG) and (Gg). The alleles for
yellow pod color are (gg). |
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Definition
| A dominant trait is one which will be expressed if one of the parents has the gene for that trait |
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| A recessive trait is one that will be expressed only if both parents carry the trait. |
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| has no noticeable effect on the organism's appearance (lowercase letter symbolizes a recessive allele, y) |
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| determines the organisms appearance (capital letter symbolizes dominance, Y) |
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| a handy diagrammatic device for predicting the allele composition of offspring from a cross between individuals of known genetic makeup |
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| An organism that has two different alleles for a gene (Yy)... produce different allele, are not true breeders |
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| an organisms appearance or observable traits |
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| an organisms genetic makeup |
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| Breeding an organism of unknown genotype with a recessive homozygote... If all the offspring are the same, the organism has a homozygous dominate allele, if the offspring have a 1:1 ratio then the organism has a heterozygous allele. |
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| The hybrid of parents that differ at only one gene locus, for which each parent is homozygous with a different allele. meaning one parent was YY and the other was yy and all the offspring were Yy. |
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Definition
| a cross between monohybrids (the F2 group) |
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Definition
the offspring of two individuals that differ with respect to two pairs
of genes; an individual heterozygous for two pairs of genes (one parent is YYSS and the other is yyss producing offspring that were YySs) |
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Definition
| a cross between dihybrids (the F2 group) (9:3:3:1 ratio)...supports independent assortment |
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| Law of independent assortment |
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Definition
| Each pair of alleles segregates independently of each other pair of alleles during gamete formation. (this only applies to genes located on different chromosomes) |
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Definition
| to determine the probability two events (say two coins tosses to both be heads), multiple the probability of one event by the probability of the other |
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| the probability that any one of two or more mutually exclusive events will occur is calculated by adding their individual probabilities |
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| F1 offspring always look like one of the two parental varieties (phenotypes of heterozygote and the dominate homozygote are indistinguishable) |
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| F1 hybrids have a phenotype somewhere between those of the two parental varieties |
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| the two alleles each affect the phenotype is separate-distinguishable ways. |
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| an inherited disorder in humans... the brain of a child with tay sachs disease cannot metabolize certain lipids because a crucial enzyme does not work properly... Lipids begin to accumulate in the brain, the child begins to suffer seizures, blindness, and degradation of motor & mental performance and dies within a few years |
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| genes that have multiple phenotypic effects.... a single gene can affect a number of characteristics in an organism |
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| The phenotypic expression of a gene at one locus alters that of a gene at a second locus... think about the black lab example, black labs are either BB or Bb while chocolate labs are bb, but in order for the labs to be brown of black they must also have EE or Ee, if they have ee then the lab with be yellow... ratio for this is 9:3:4= black, chocolate, yellow |
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| A heritable feature that varies continuously over a range rather that in an either-or fashion |
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| an additive effect of two or more genes on a single phenotypic character |
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| the range of phenotypes produced by a single genotype due to environmental influences. |
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| Many factors, both genetic and environmental, collectively influence phenotype. |
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| a diagram of a family tree with conventional symbols, showing the occurrence of heritable characters in parents and offspring over multiple generations. |
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| One who is phenotypically normal in regard to a disorder, heterozygotes may transmit the recessive allele to their offspring. |
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| most common lethal genetic disease in the US... causes abnormally high concentrations of extracellular chloride, which causes the mucus that coats certain cells to become thicker, which leads to poor absorption of nutrients, chronic bronchitis, and recurrent bacterial infections |
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Definition
| Most common with people of African decent... substitution of a single amino acids in the hemoglobin protein of red blood cells, cause the cell to become sickle shaped under physical stress, high altitudes. This sickle shape can cause the blood cells to clump and clog small blood vessels which can lead to many problems in the body. Heterozygotes are not only carriers but can also suffer for the disease. |
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