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39 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Allele |
an alternate form that a gene may have for a single trait; can be dominant or recessive |
ex) X and y
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Autosome |
any chromosome that is not a sex chromosome |
ex) chromosomes numbers 1 through 22 |
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Back cross |
To cross (a hybrid) with one of its parents or with an individual genetically identical to one of its parents |
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Cline |
a gradation in one or more characteristics within a species or other taxon, especially between different populations |
ex) large population of trees, where those in the South have larger leaves than those in the North |
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Codominance |
When two alleles are dominant and affect the phenotype in two different but equal ways |
ex) A and B blood types |
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Continuous variation |
variation that has no limit on the value that can occur within a population |
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Cross |
a method of hybridization or the hybrid so produced |
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Dihybrid cross |
A cross between two individuals, concentrating on two definable traits |
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Discontinuous variation |
variation in phenotypic traits in which types are grouped into discrete categories with few or no intermediate phenotypes |
ex) human blood groups (only four types) |
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Dominant |
A trait expressed preferentially over another trait |
ex) Aa (capital A) |
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F1 |
Offspring of a cross between true breeding plants, homozygous for the trait of interest |
ex) first generation |
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F2 Generation |
Offspring of a cross involving the F1 generation |
ex) second generation |
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Genetic counseling |
the process of helping people understand and adapt to the medical, psychological and familial implications of genetic contributions to disease |
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Genomic imprinting |
the epigenetic phenomenon by which certain genes are expressed in a parent-of-origin-specific manner. If the allele inherited from the father is imprinted, it is thereby silenced, and only the allele from the mother is expressed |
ex) diseases such as Angelman syndrome |
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Genotype |
The genetic constitution of an organism with respect to a trait. For a single trait on an autosome, an individual can be homozygous for the dominant trait, heterozygous, or homozygous for the recessive trait |
ex) Yellow seeds are dominant, but yellow seeded plants could have a genotype of either YY or Yy. |
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Heterozygous |
having two different alleles for a trait |
ex) Aa |
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Homozygous |
Both alleles for a trait are the same in an individual |
ex) AA or aa |
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Incomplete dominance |
creates a blended phenotype; one allele is not completely dominant over the other |
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Independent assortment |
formation of random combinations of chromosomes in meiosis and of genes on different pairs of homologous chromosomes by the passage according to the laws of probability of one of each diploid pair of homologous chromosomes into each gamete independently of each other pair |
ex) helps variation |
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Lethal allele |
Mutated genes that are capable of causing death |
ex) sickle cell anemia
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Linkage |
genes that are inherited together on the same chromosome |
ex) three inheritance patterns are possible: non-linkage, Partial linkage, and complete linkage |
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Monohybrid cross |
Involving the study of only one character |
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Multiple Alleles |
When a gene has more than two alleles |
ex) blood type |
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Non-disjunction |
the failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division |
ex) usually resulting in an abnormal distribution of chromosomes in the daughter nuclei |
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Non-nuclear inheritance |
the inheritance of genetic information from sources other than the chromosomes |
ex) DNA in chloroplasts and mitochondria |
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Pedigree analysis |
the study of an inherited trait in a group of related individuals to determine the pattern and characteristics of the trait, including its mode of inheritance, age of onset, and phenotypic variability |
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Phenotype |
The physical traits that appear in an individual as a result of its genotype |
ex) color, fur texture, etc. |
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Phenotypic plasticity |
the ability of one genotype to produce more than one phenotype when exposed to different environments |
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Polygenetic inheritance |
combined effect of two or more genes on a single character |
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Punnett square |
a diagram that is used to predict an outcome of a particular cross or breeding experiment |
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Pure-breeding (aka true-breeding) |
produce offspring of the same variety |
ex) AA x AA = AA |
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Recessive |
The opposite of dominant. A trait that is preferentially masked |
x) aa (lowercase) |
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Segregation |
the formation of unique gametes from the genotype of the parents |
ex) Mendel’s Law of Segregation |
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Selfing |
causing (an animal or plant) to breed with or fertilize one of the same hybrid origin or strain |
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Sex chromosome |
A type of chromosome in the genome that is involved in the determination of the sex as well as the development of sexual characteristics in an organism. It occurs in pairs in somatic cells while singly in sex cells |
ex) gametes |
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Sex-limited traits |
a genetic trait exhibited by one sex only, although not determined by an X-linked gene |
ex) milk production in mammals |
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Sex linked gene |
A gene located on a sex chromosome, usually the X-chromosome |
ex) color blindness |
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Test cross |
the crossing of an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype |
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Trait |
a distinguishing quality or characteristic, typically one belonging to a person |
ex) hair/ eye color, etc. |
