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71 Cards in this Set

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Differential expression of a gene depending on whether it is inherited from the mother or the father.
Genomic Imprinting
Phenotype of the heterozygote is the same as the phenotype of one of the homozygotes.
Complete Dominance
Phenotype of the heterozygote is intermediate between the phenotypes of the two homozygotes.
Incomplete Dominance
Phenotype of the heterozygote includes the phenotypes of both homozygotes.
Codominance
When a genotype does not always produce the expeced phenotype.
Incomplete Penetrance
The percentage of individuals having a particular genotype that express the expected phenotype.
Penetrance
The degree to which a character is expressed.
Expressivity
Incomplete Penetrance and variable expressivity result from the influence of _____ and ____ on the phenotype.
Other genes and environmental facors
Causes death at an early stage in development, often before birth.
Lethal Allele
One gene masks the effect of a gene at a different locus.
Epistasis
A ____ ratio is almost always produced by a lethal allele.
2:1
If heterozygotes and homozygotes both die then a lethal allele is ____.
Dominant
If a lethal allele causes death only in homozygotes, then it is ____.
Recessive
Truly dominant lethal alleles can be transmitted. T/F.
False. They cannot be transmitted unless they are expressed after the onset of reproduction, such as Huntington's Disease.
Lethal alleles modify the ratio of progeny resulting from a cross. T/F.
True
More than two alleles are present within a group of individuals.
Multiple Alleles
Multiple Alleles can also be referred to as an ____ ____.
Allelic Series
When multiple alleles exist within a group of organisms, the genotype of an individual diploid organism will consist of ____ alleles.
Two
When working with multiple alleles, the number of genotypes possible can be found using this equation.
[n(n+1)]/2
List two examples of multiple allele systems from the book.
*Color in Mallards
*ABO Blood in Humans
In humans, blood type A can be:
IAIA or IAi
In humans, blood type B can be:
IBIB or IBi
In humans, blood type AB can be:
ONLY IAIB
In humans, blood type O can be:
ONLY ii
Interaction between the effects of genes at different loci where genes at one locus depend on the presence of genes at other loci.
Gene Interaction
Dominance is an interaction between genes at the same locus, or an ____ interaction.
Allelic
Dominance effects the way in which genes are inherited. T/F.
False. Dominance influences the way in which genes are expressed, but not the way in which they are inherited.
If Y is a recessive lethal allele and we cross Yy with Yy, what percent of the offspring will be yellow?
(Y=yellow, y=white)
2/3
List two examples of novel phenotypes produced by gene interaction at two loci.
*Comb shape in chickens
*Color in Peppers
A gene that masks another gene.
Epistatic Gene
A gene whose effect is masked by another gene.
Hypostatic Gene
Epistatic Genes may be dominant or recessive in their effects. T/F?
True.
An example of Recessive Epistasis is:
Coat Color in Labs
An Example of Dominant Epistasis is:
Summer Squash
Normal Gene Interaction without Epistasis F1 generation cross produces what ratio?
9:3:3:1
Gene Interaction with Recessive Epistasis produces what ratio when the F1 generation is crossed?
9:3:4
Gene Interaction with Dominant Epistasis F1 generation cross produces the ratio:
12:3:1
A case where a gene has an effect on an early step which affects subsequent steps is a case of ____.
Epistasis
The equation [n(n+1)]/2 is used to find what?
The number of genotypic combinations in a mutiple allele system.
Duplicative Recessive Epistasis creates a ratio of:
9:7
In duplicative recessive epistasis, there must be __ recessive genes at ___ loci.
Two, one or both
In general, we can use which equation to find progeny proportion?
(1/2) to the 2n power
Name an example of Duplicative Recessive Epistasis
Albinism in Snails
We use this test to find out whether or not two mutations occur at the same locus.
Complementation Test
In the Complementation Test, who is crossed?
Two parents that are homozygous for different mutations.
If a Complementation Test is done, and a wild type phenotype appears, what do we know about the mutations?
The mutations are non-allelic genes.
When we do the complementation test on white and apricot eyed flies, we find that:
The mutations are allelic, or located at the same locus.
Traits which are determined by autosomal genes and are inherited according to Mendel's principles, but are expressed differently in males and females.
Sex-Influenced Characteristics
A trait that has higher penetrance in one sex than the other.
Sex-Influenced Characteristic
What would we say about the penetrance in reference to sex-linked characteristics?
Penetrance is higher in one sex than the other.
What is an example of a sex-Influenced characteristic (non-human)?
Beards in Goats
Encoded in autosomal genes, and expressed in only one sex. Has no penetrance at all in the other sex.
Sex-Limited Characteristic
If we have a case where the genotype of a male and female are the same, but the phenotypes are different, then we have a:
Sex-Limited Characteristic
If a characteristic can be inherited from either parent, but is seen in only one sex, then the trait is
Sex-limited
An example of a Sex-Influenced characteristic in humans is:
Male pattern Baldness
An Example of a Sex-Limited Characteristic in humans is:
Precocious Puberty
Characteristics which are encoded by genes in the cytoplasm
Cytoplasmic Inheritance
The phenotype of the offspring is determined not by its own genotype but by its mother's genotype.
Genetic Maternal Effect
In Genetic Maternal Effect, the genes are inherited from both parents. T/F
True. The genes are inherited from both parents, but the genotype of only the mother determines the phenotype of the offspring.
The genes for a characteristic are inherited only from one parent, usually the mother.
Cytoplasmic Inheritance
An Example of Genetic Maternal Effect is:
Shell coiling in snails
What is the major difference between cytoplasmic inheritance and genetic maternal effect?
In Cytoplasmic Inheritance, genes are transmitted through only one of the sexes, usually the female. In Genetic Maternal Effect, the offspring receives genes from both parents, but takes the phenotype of the mother only.
A genetic trait becomes more strongly expressed or is expressed at an earlier age from generation to generation
Anticipation
The range of phenotypes produced by a genotype in different envoronments is called:
The Norm of Reaction
An allele whose product is functional only at certain temperatures.
Temperature Dependent Allele
When environmental factors alone produce a phenotype that is the same as a genotype.
Phenocopy
Characteristics which have only a few easily distinguisable phenotypes.
Discontinuous Characterisics
Characteristics which have to be described quantitatively because there are so many variations.
Continuous or Quantitative Characteristics
Characteristcs encoded by genes at many loci.
Polygenic Characteristics
One gene effects mutiple characteristics
Pleiotropy
Continuous Characteristics which are both polygenic and influenced by the environment
Multifactorial Characteristics