Chapter 12: Mendelian Genetics Flashcards
List and explain the four components of Mendel’s hypothesis that led him to deduce the law of segregation.
1: The adult plants carry a pair of factors that govern each trait.
2: If an individual’s pair of genes consist of different alleles one is dominant over the other, which is recessive.
3: The pair of alleles that control a character segregate as gametes are formed; half the gametes carry one allele, and the other half carry the other.
4: The alleles of the genes that govern the two traits assort independently during the formation of gametes.
Define the following terms: true breeding, hybridization, mono hybrid cross, P generation, F1 generation, F2 generation.
True Breeding: a form of breeding that passes traits without change from one generation to the next when bred with themselves.
Hybridization:
Mono hybrid cross: a cross between two individuals that are each heterozygous for the same pair of alleles.
P generation: Parental generation of a test cross
F1 generation: First generation of a test cross
F2 generation: Second generation of a test cross
Use a Punnet square to predict offspring of a monohybrid cross, stating phenotypic and genotypic ratios of F2 generation.
3:4
Phenotypic expression of traits
Dominant: recessive
1:2:1
Genotypic,
homozygous dominant: heterozygous dominant: homozygous recessive.
Distinguish between following pairs of terms: homozygous and heterozygous, dominant and recessive, genotype and phenotype
Homozygous means a pair of the same alleles. Heterozygous means a pair of different alleles.
Dominant means an allele is expressed phenotypically in spite of the other allele. Recessive alleles are expressed only when the paired allele is the same.
A Genotype is the pair of alleles that govern the trait.
A phenotype is a physical trait.
Explain how a test cross can be used to determine if an individual with dominant phenotype is homozygous or heterozygous
By performing a test cross (a cross with a homozygous recessive genotype) we can determine if a dominant phenotype has a homozygous genotype by seeing if a recessive trait manifests in the F1 generation.
Use a Punnet square to predict the results of a dihybrid cross and state phenotype and genotype ratios of F2 generation.
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Use rule of multiplication to calculate probability that an F2 individual will be homozygous recessive or dominant.
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Given a Mendelian cross, use the rule of addition to calculate the probability that a particular F2 individual will be heterozygous.
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Use the laws of probability to predict, from a trihybrid cross between two individuals that are heterozygous for all three traits, the expected proportion of offspring that would be
A: homozygous dominant for all three
B: heterozygous for all three
C: homozygous recessive for two and heterozygous for the third.
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Explain why it was important Mendel used large sample sizes in his experiments.
By using large sample sizes, Mendel was able to decrease his margin of error regarding the ratio of phenotypes and ensure recessive traits had a chance to manifest from a heterozygous parent.
Give an example of incomplete dominance and explain why it does not support the blending theory of inheritance.
Labrador retrievers…
Explain how phenotypic expression in the heterozygote differs from complete dominant, incomplete dominance, and co-dominance.
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Describe the inheritance of the ABO system and explain why the I(A) and I(B) are said to be co-dominant.
They are co-dominant because they both express their phenotype without masking the other. Since O is defined as a lack of the phenotype of I(A) or I(B) it is recessive.
Define and give examples of pleiotropy and epistasis
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Given a simple family pedigree, deduce genotypes for specific family members.
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