3. These questions will explore the probability of children inheriting a dominant disorder from their parents. a. If the disorder is dominant to being normal and we use the letter ββAββ for allele symbols, what allele is ββAββ? What allele is ββaββ? b. What is the probability that a child will inherit a dominant disorder if one parent is homozygous for the trait and the other is normal? c. What is the probability that a child will inherit a dominant disorder if both parents are homozygous for the trait? d. Assign gene symbols and determine the genotype of the individuals in this pedigree. How can you tell that this pedigree is following a dominant trait? e. Challenge! What is the probability that the individual at the end of the pointer is heterozygous? 4. These questions will explore the probability of children inheriting a recessive disorder from their parents. a. If the disorder is recessive to being normal and we use the letter ββAββ for allele symbols, what allele is ββAββ? What allele is ββaββ? b. What is the probability that a child will inherit the recessive disorder if one parent has the disorder and the other parent is homozygous normal? c. What is the probability that a child will inherit a recessive disorder if both parents are heterozygous for the trait? d. Assign gene symbols and determine the genotype of the individuals in this pedigree. How can you tell this pedigree is following a recessive trait? e. Challenge! What is the probability that the individual at the end of the pointer is heterozygous? Assume this individual is homozygous.
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For a dominant disorder, the allele "A" is the dominant allele (causing the disorder), and "a" is the recessive allele (normal). Show moreβ¦
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Challenge question: practicing probability Two parents want to know if their child will be affected by a rare recessive disorder that runs in both their families. Both parents are unaffected but have a 50% chance of being a carrier. What is the chance their child will be unaffected, but still be a carrier of the recessive allele? This is challenging because each parent has a 1/2 chance of being homozygous for the unaffected allele so they can only pass on an unaffected allele...OR each parent has a 1/2 chance of being heterozygous AND thus have a 1/2 chance of passing on the dominant allele. Because a parent cannot be both DD and Dd (these are mutually exclusive possibilities), we'll need to use the sum rule for part of this calculation to take both possibilities into account. A 1/8 B 1/16 C 3/8 D 3/16 E 1/512 Human pedigree pattern identification: Example 1 The allele that causes the affected phenotype is _____. (Can you explain why?) A definitely autosomal dominant B definitely autosomal recessive C could be either dominant or a very common autosomal recessive allele
Bryan V.
Refer to the pedigree below for this question. Individuals who are shaded have the autosomal recessive disorder. Since it is a rare disorder, assume that anyone entering the pedigree (someone whose parents are not in the pedigree) is homozygous, unless there is evidence to the contrary. Those who are not shaded show the dominant phenotype. Let A and a represent the dominant and recessive alleles, respectively. Fill in the table below to indicate the genotype or probability function for the genotype of each individual. Give all probabilities as fractions that are simplified to the lowest value. Type your fractions in #/# format without spaces. For example, one-half should be entered as 1/2. Failure to correctly follow these directions will result in your answer being marked as incorrect. Fill in the table below to indicate the genotype or the genotype probability of the individual. Two are completed as examples. Individual Genotype Probability Formula I-2 0 AA + 1 Aa + 0 aa I-4 AA + Aa + aa II-2 AA + Aa + aa II-6 AA + Aa + aa II-7 1/3 AA + 2/3 Aa + 0 aa III-2 AA + Aa + aa III-3 AA + Aa + aa Give all probabilities as fractions that are simplified to the lowest value. Type your fractions in #/# format without spaces. Suppose that III-3 and III-8 have a child. What is the probability that their first child is genotype Aa?
Supreeta N.
A couple has four children, two boys and two girls. The father is affected by a single gene disorder but the mother is not. All four children are affected by the same disorder as the father. Which one of the following is NOT possible? (heterozygous and homozygous refer to the gene associated with the disorder) The allele that causes the disorder is dominant; the father is heterozygous and the mother is homozygous The allele that causes the disorder is dominant; the father is homozygous and the mother is homozygous The allele that causes the disorder is recessive; the father is homozygous and the mother is homozygous. The allele that causes the disorder is recessive; the father is homozygous and the mother is heterozygous
Sri K.
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