23 Questions
Which genetic disease is inherited as a dominant allele in humans?
Huntington’s disease
What is the frequency of Marfan syndrome, caused by a dominant allele, in humans?
1/10,000
Which disease exhibits a dominant pattern of inheritance in pedigrees?
Familial hypercholesterolemia
What are the characteristics of autosomal recessive inheritance?
If it appears in more than one family member, typically it is seen only within a sibship, not in other generations
How can dominant traits be recognized in pedigrees?
Affected children always have at least one affected parent
What dominance relationship is defined when the phenotype of the heterozygote resembles one of the two parents?
Complete dominance
What does the R allele encode?
Starch branching enzyme (Sbe1)
What is the result of the r allele not making Sbe1?
Wrinkled peas
Which gene encodes the Stay green enzyme (Sgr)?
Y allele
What happens when the y allele does not make Sgr?
Chlorophyll is not broken down and the peas remain green
According to the molecular principles, what does a recessive allele usually not encode?
A functional protein
What is the effect of the absence of Sbe1 due to the r allele?
Buildup of sucrose and unbranched starch
Which allele usually determines a normally functioning protein according to the molecular principles?
Dominant allele
What is the function of Sgr encoded by the Y allele?
Helps break down chlorophyll
What is the result of chlorophyll not being broken down due to the y allele?
The peas remain green
What is the effect of a recessive allele on a protein's activity according to the molecular principles?
It usually does not encode a functional protein
In incomplete dominance, what is the phenotypic ratio when crossing two heterozygous individuals?
1:2:1
What type of dominance relationship results in F1 hybrids displaying traits of both parents?
Codominance
Which allele controls the type of sugar polymer on the surface of red blood cells in codominance?
Gene I
What does variation in dominance relations between alleles depend on?
The biochemical functions of the proteins
What molecular explanation is provided for incomplete dominance in snapdragon flower color?
The normal allele produces an enzyme involved in pigment production
What is the phenotype ratio when crossing two heterozygous individuals in complete dominance?
3:1
Which type of dominance relationship does not affect the transmission of alleles?
Complete dominance
Test your knowledge on the molecular explanation for Mendel's pea traits including shape and color. Understand the role of specific alleles and enzymes in determining pea traits.
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