A pedigree is a chart that shows the inheritance of a trait over several generations. A pedigree is commonly created for families, and it outlines the inheritance patterns of genetic disorders and traits. A pedigree can help predict the probability that offspring will inherit a genetic disorder. Pictured below is a pedigree displaying recessive inheritance of a disorder through three generations ( Figure 1.1). From studying a pedigree, scientists can determine the following: If the trait is sex-linked (on the X or Y chromosome) or autosomal (on a chromosome that does not determine sex). If the trait is inherited in a dominant or recessive fashion. Sometimes pedigrees can also help determine whether individuals with the trait are heterozygous (two different alleles) or homozygous (two of the same allele). Some points to keep in mind when analyzing a pedigree are: 1. With autosomal recessive inheritance, all affected individuals will be homozygous recessive. 2. With dominant inheritance, all affected individuals will have at least one dominant allele. They will be either homozygous dominant or heterozygous. 3. With sex-linked inheritance, more males (XY) than females (XX) usually have the trait. Sex-linked inheritance is usually recessive.
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a pedigree shows family relationships.
--> a. true b. false
a pedigree can be useful in understanding inheritance.
--> a. true b. false
in autosomal recessive inheritance, all children of an couple with both parents having the recessive trait
a) will not have the trait. --> b) will all have the trait. c) may or may not have the trait. d) cannot be determined from the information given.
in autosomal dominant inheritance, a homozygous dominant affected father will have children
a) that may or may not be affected. b) that are not affected. --> c) that are all affected. d) cannot tell from the information given.
in sex-linked inheritance, the pedigree will most likely show
--> a) more affected males. b) more affected females. c) an equal number of affected males and females. d) no affected individuals.
in autosomal recessive inheritance, all affected individuals
a) will be heterozygous. b) will be heterozygous recessive. c) will be homozygous dominant. --> d) will be homozygous recessive.
in autosomal dominant inheritance, all affected individuals
--> a) will be homozygous dominant or heterozygous. b) will be homozygous recessive or heterozygous. c) will be heterozygous. d) cannot be determined from the information given.
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