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What is the central concept of Mendelian inheritance?
What is the central concept of Mendelian inheritance?
- The blending of parental traits to create intermediate offspring traits.
- The transmission of traits controlled by a single gene with two alternative alleles. (correct)
- The inheritance of acquired characteristics from parents.
- The transmission of traits controlled by multiple genes.
Which of the following statements accurately describes Gregor Mendel’s contribution to the field of genetics?
Which of the following statements accurately describes Gregor Mendel’s contribution to the field of genetics?
- He discovered the structure of DNA.
- He identified chromosomes as the carriers of genetic information.
- He developed the theory of natural selection.
- He formulated foundational principles of heredity through experimentation with pea plants. (correct)
In genetics, what distinguishes 'factors,' as described by Mendel, from what are known today as genes?
In genetics, what distinguishes 'factors,' as described by Mendel, from what are known today as genes?
- Factors control only physical traits, while genes control all traits.
- Factors are only present in plants, while genes are present in animals.
- Factors are inherited only from the mother, while genes are inherited from both parents.
- There is no difference; Mendel simply used a different term before the concept of the gene was fully developed. (correct)
What is the primary focus of a monohybrid cross?
What is the primary focus of a monohybrid cross?
Before performing crosses, Mendel ensured that his pea plants were 'true-breeding'. What does 'true-breeding' mean in the context of genetics?
Before performing crosses, Mendel ensured that his pea plants were 'true-breeding'. What does 'true-breeding' mean in the context of genetics?
In the context of Mendelian genetics, what is the F1 generation?
In the context of Mendelian genetics, what is the F1 generation?
What phenotypic ratio did Mendel consistently observe in the F2 generation of a monohybrid cross?
What phenotypic ratio did Mendel consistently observe in the F2 generation of a monohybrid cross?
Why is a Punnett square an important tool in studying genetics?
Why is a Punnett square an important tool in studying genetics?
In a monohybrid cross, if the F1 generation has a heterozygous genotype (Tt), what genotypes will be present in the F2 generation?
In a monohybrid cross, if the F1 generation has a heterozygous genotype (Tt), what genotypes will be present in the F2 generation?
How does the genotypic ratio differ from the phenotypic ratio in the F2 generation of a monohybrid cross?
How does the genotypic ratio differ from the phenotypic ratio in the F2 generation of a monohybrid cross?
What is the significance of Mendel's conclusions about hereditary 'factors' in the F1 generation?
What is the significance of Mendel's conclusions about hereditary 'factors' in the F1 generation?
In the context of Mendelian inheritance, if both dominant and recessive factors are present in an offspring, which trait will be expressed?
In the context of Mendelian inheritance, if both dominant and recessive factors are present in an offspring, which trait will be expressed?
What is the purpose of performing a dihybrid cross?
What is the purpose of performing a dihybrid cross?
In a dihybrid cross, what is produced by crossing round-yellow seeds (RRYY) with wrinkled-green seeds (rryy)?
In a dihybrid cross, what is produced by crossing round-yellow seeds (RRYY) with wrinkled-green seeds (rryy)?
In the F2 generation of a dihybrid cross, what phenotypic ratio typically results from the cross of two F1 generation plants (RrYy x RrYy)?
In the F2 generation of a dihybrid cross, what phenotypic ratio typically results from the cross of two F1 generation plants (RrYy x RrYy)?
What is the relationship between Mendel's Laws of Segregation and Independent Assortment?
What is the relationship between Mendel's Laws of Segregation and Independent Assortment?
What does the Law of Segregation state?
What does the Law of Segregation state?
Which of the following is an example of the Law of Independent Assortment?
Which of the following is an example of the Law of Independent Assortment?
How does a dihybrid cross demonstrate the Law of Independent Assortment?
How does a dihybrid cross demonstrate the Law of Independent Assortment?
Considering a dihybrid cross involving seed shape (R=round, r=wrinkled) and seed color (Y=yellow, y=green), what proportion of the F2 generation would be expected to have wrinkled seeds and yellow color?
Considering a dihybrid cross involving seed shape (R=round, r=wrinkled) and seed color (Y=yellow, y=green), what proportion of the F2 generation would be expected to have wrinkled seeds and yellow color?
Mendel’s experimental approach was significant because it demonstrated the importance of which factor in scientific research?
Mendel’s experimental approach was significant because it demonstrated the importance of which factor in scientific research?
Why was it important for Mendel to use pure lines in his experiments?
Why was it important for Mendel to use pure lines in his experiments?
What is the difference between a homozygous and a heterozygous genotype?
What is the difference between a homozygous and a heterozygous genotype?
If 'T' represents the dominant allele for tallness and 't' represents the recessive allele for shortness in pea plants, what is the phenotype of a plant with the genotype 'Tt'?
If 'T' represents the dominant allele for tallness and 't' represents the recessive allele for shortness in pea plants, what is the phenotype of a plant with the genotype 'Tt'?
What is the expected phenotypic ratio of a cross between two heterozygous individuals (Pp x Pp), where 'P' represents the dominant allele and 'p' represents the recessive allele?
What is the expected phenotypic ratio of a cross between two heterozygous individuals (Pp x Pp), where 'P' represents the dominant allele and 'p' represents the recessive allele?
What is the purpose of test cross?
What is the purpose of test cross?
Which cross could be used to perform a test cross?
Which cross could be used to perform a test cross?
In a test cross, if all the offspring display the dominant trait, what can be inferred about the genotype of the parent with the dominant phenotype?
In a test cross, if all the offspring display the dominant trait, what can be inferred about the genotype of the parent with the dominant phenotype?
What result from a test cross would indicate that the parent with the dominant phenotype is heterozygous?
What result from a test cross would indicate that the parent with the dominant phenotype is heterozygous?
How does understanding Mendelian inheritance contribute to modern genetics?
How does understanding Mendelian inheritance contribute to modern genetics?
Flashcards
What is inheritance?
What is inheritance?
The passing of traits from parents to offspring.
What is Mendelian inheritance?
What is Mendelian inheritance?
Crosses involving a single gene with two alternative alleles.
What are Mendelian crosses?
What are Mendelian crosses?
Experiments to study inheritance patterns.
What is a monohybrid cross?
What is a monohybrid cross?
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What is phenotype?
What is phenotype?
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What is genotype?
What is genotype?
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What does homozygous mean?
What does homozygous mean?
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What does heterozygous mean?
What does heterozygous mean?
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What is self-cross?
What is self-cross?
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What is the F1 generation?
What is the F1 generation?
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What is the F2 generation?
What is the F2 generation?
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What is a dominant allele?
What is a dominant allele?
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What is a recessive allele?
What is a recessive allele?
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What is a Punnett square?
What is a Punnett square?
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What is a dihybrid cross?
What is a dihybrid cross?
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Study Notes
- Genetics is the study of inheritance and variation in organisms
Mendelian Inheritance
- Austrian monk Gregor Mendel first explained how characteristics are passed between generations in the mid-19th century
- Mendel discovered the principles of heredity by experimenting with garden peas (Pisum sativum) for eight years
- Mendel established different terminologies used in genetics, such as factors (later genes, alleles), dominant, recessive, genotype, homozygous, heterozygous, phenotype, and more
- Mendelian inheritance is the patterns of inheritance of traits controlled by a single gene with two alternative alleles, from parent to offspring
- Mendel's principles of heredity include the law of segregation and the law of independent assortment
Mendelian Crosses
- Gregor Mendel, known as the father of genetics, experimented with pea plants (Pisum sativum)
- Mendel studied seven pairs of different characters of pea plants with contrasting traits that exist in two forms
- Examples of traits studied include seed shape (round vs. wrinkled), seed color (yellow vs. green), flower color (purple vs. white), and stem length (tall vs. short)
- Mendel conducted monohybrid crosses, dihybrid crosses, and test crosses to determine the mechanism of inheritance
Monohybrid Cross
- Involves the study of the inheritance of a single character from each parent
- Mendel verified the purity of plants through self-crosses, ensuring tall plants produced only tall offspring and dwarf plants produced only dwarf offspring
- Cross-pollination of pure lines for contrasting characters resulted in the F1 generation, where only one trait was visible
- Self-pollination of the F1 generation gave rise to the F2 generation, where both traits were observed in a 3:1 ratio of dominant to recessive traits
- Dominant traits appear in the F1 generation, while recessive traits appear for the first time in the F2 generation
- Capital letters denote dominant alleles, and lowercase letters denote recessive alleles
- A Punnett square is a chart used to determine the expected ratios of genotypes and phenotypes in offspring providing probabilities
- The phenotypic ratio in the F2 generation is 3:1 (3 tall, 1 short), and the genotypic ratio is 1:2:1 (1 TT, 2 Tt, 1 tt)
- Round (RR), yellow (YY), inflated (II), green (GG), purple (PP), axial (AA), and tall (TT) were identified as dominant traits, while wrinkled (rr), green (yy), constricted (ii), yellow (gg), white (pp), terminal (aa), and short (tt) were identified as recessive traits
- Each parent starts with two hereditary "factors," one dominant and one recessive
- Factors separate in the parent, with only one factor from each parent contributed to the offspring
- Each offspring inherits one factor from each parent
- If the dominant factor is present, it will be expressed, even if the recessive factor is also present
- The recessive factor will be expressed if only recessive factors are present
Dihybrid Cross
- A cross between two traits of individuals at a time
- The cross between round-yellow seed (RRYY) and wrinkled-green seed (rryy) resulted in all round yellow seeds (RrYy) in the F1 generation
- The cross between F1 generations (RrYy x RrYy) resulted in round-yellow, wrinkled-yellow, wrinkled-green, and round-green offspring
- Phenotypic ratio of 9:3:3:1 (9 round-yellow, 3 round-green, 3 wrinkled-yellow, 1 wrinkled-green)
- Genotypic ratio of 1:2:2:4:1:2:1:2:1
- Mendel discovered the laws of segregation and independent assortment from monohybrid and dihybrid crosses
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