Testes determining factor
the gene product comes from the SRY gene that underlies male genital development?
Mullerian inhibiting substance
One of the two testicular hormones and it results in regression of female internal duct structure in XY males
incomplete dominence
Refers to the phenotype of a heterozygote that is intermediate between the phenotypes of the two homozygotes.
codominence
Type of allelic interaction in which the heterozygote simultaneously expresses traits of both homozygotes.
incomplete penetrance
Refers to a genotype that does not always express the expected phenotype. Some individuals possess the genotype for a trait but do not express the phenotype.
penetrance
Percentage of individuals with a particular genotype that express the phenotype expected of that genotype.
expressivity
Degree to which a trait is expressed
lethal allele
Causes the death of an individual organism, often early in development, and so the organism does not appear in the progeny of a genetic cross. Recessive lethal alleles kill individual organisms that are homozygous for the allele; dominant lethals kill bot
multiple alleles
Presence in a group of individuals of more than two alleles at a locus. However, each member of the group has only two of the possible alleles.
compound heterozygote
An individual with two different recessive alleles at a locus that results in a recessive phenotype.
gene interaction
Interaction between genes at different loci that affect the same characteristic.
hypostatic gene
Gene that is masked or suppressed by the action of a gene at a different locus.
complementation test
Test designed to determine whether two different mutations are at the same locus (are allelic) or at different loci (are nonallelic). Two individuals that are homozygous for two independently derived mutations are crossed, producing F1 progeny that are he
complementation
Two different mutations in the heterozygous condition are exhibited as the wild-type phenotype; indicates that the mutations are at different loci.
sex influence charectaristic
Characteristic encoded by autosomal genes that are more readily expressed in one sex. For example, an autosomal dominant gene may have higher penetrance in males than in females or an autosomal gene may be dominant in males but recessive in females.
sex limited charectaristic
Characteristic encoded by autosomal genes and expressed in only one sex. Both males and females carry genes for sex-limited characteristics, but the characteristics appear in only one of the sexes.
genetic maternal effect
Differential expression of a gene that depends on the sex of the parent that transmitted the gene. If the gene is inherited from the father, its expression differs from that if the gene is inherited from the mother.
genomic imprinting
Differential expression of a gene that depends on the sex of the parent that transmitted the gene. If the gene is inherited from the father, its expression differs from that if the gene is inherited from the mother.
epigenetics
Phenomena due to alterations to DNA that do not include changes in the base sequence; often affect the way in which the DNA sequences are expressed. Such alterations are often stable and heritable in the sense that they are passed from one cell to another
anticipation
Increasing severity or earlier age of onset of a genetic trait in succeeding generations. For example, symptoms of a genetic disease may become more severe as the trait is passed from generation to generation.
temperature sensitive allele
expressed only at certain temperatures
phenocopy
An environmentally caused trait that occurs in a familial pattern, mimicking inheritance and is the same as the phenotype produced by a genotype.
discontinuous charectaristic
Exhibits only a few, easily distinguished phenotypes. An example is seed shape in which seeds are either round or wrinkled.
continuous charectaristic
Displays a large number of possible phenotypes that are not easily distinguished, such as human height.
quantitative charectaristic
Continuous characteristic; displays a large number of possible phenotypes, which must be described by a quantitative measurement
polygenic charectaristic
encoded by genes at many loci
pleiotropy
A single gene having multiple effects on an individuals phenotype (more than one phenotypic expression)
multifactorial charectaristic
determined by multiple genes and environmental conditions
epistastic gene
Masks or suppresses the effect of a gene at a different locus.
Complete dominence
Refers to an allele or a phenotype that is expressed in homozygotes (AA) and in heterozygotes (Aa); only the dominant allele is expressed in a heterozygote phenotype.
phenotypic ratio of incomplete dominence
1:2:1
variable expressivity
A trait seen in all individuals carrying the mutant gene but expressed differently among individuals
heteroplasmy
Presence of both normal and mutated mtDNA, resulting in variable expression in mitochondrial inherited disease
Interaction between genes at the same locus (allelic interaction) is
Dominence
The differential expression of a gene depending on whether it is inherited from the male or female parent is termed
genomic imprinting
Sex-influenced characteristics are determined by what type of genes?
both x and y genes
Assume that ptosis (droopy eyelid) is inherited as an autosomal dominant human trait. Among 100 people who are known to be heterozygous for the ptosis allele, 80 have ptosis and 20 have normal eyelids. What is the penetrance for ptosis?
80%
A sex- _____ characteristic is encoded by autosomal genes that are expressed only in one sex.
sex limited
A homozygous beardless male goat is crossed with a homozygous bearded female goat. What are the phenotypes of the offspring?
all males have beards and females are beardless
The percentage of individuals having a particular genotype that express the expected phenotype is the
penetrance
Males can inherit a gene for a sex-limited trait from
both parents since they are inherited autosommally
A cross between two heterozygotes produces a 2:1 phenotypic ratio in the progeny. Which is occurring in this cross?
lethal allele
A middle-aged acquaintance discloses to you that he has begun experiencing involuntary muscle movements. Other members in his family history, such as a grandmother, had experienced these symptoms, but their symptoms developed after the age of 60. What con
anticipation
Martha has blood type AB. Where are the alleles for the A and B antigens located? Assume that no crossing over has taken place.
on different homologous chromosomes
Reciprocal cross
When you switch the sex on a cross you get different results with reciprocal crosses so imprinted traits , cytoplasmic inherited traits and sex linked changed when sexes are switch