Podcast
Questions and Answers
In a cross between two homozygous black furred animals ($BB$), what is the probability of their offspring having white fur?
In a cross between two homozygous black furred animals ($BB$), what is the probability of their offspring having white fur?
- 50%
- 25%
- 0% (correct)
- 75%
If two parents with black fur ($BB$) produce offspring, what percentage of the offspring will have the same genotype and phenotype as the parents?
If two parents with black fur ($BB$) produce offspring, what percentage of the offspring will have the same genotype and phenotype as the parents?
- 100% (correct)
- 75%
- 25%
- 50%
What type of gamete(s) can a homozygous parent with the genotype $bb$ produce?
What type of gamete(s) can a homozygous parent with the genotype $bb$ produce?
- Only gametes carrying the 'b' allele (correct)
- Gametes carrying either the 'B' or 'b' allele in equal proportions
- Only gametes carrying the 'B' allele
- No gametes, as this is a recessive trait
What is the expected outcome (genotype and phenotype) of a cross between a homozygous dominant ($BB$) and a homozygous recessive ($bb$) individual?
What is the expected outcome (genotype and phenotype) of a cross between a homozygous dominant ($BB$) and a homozygous recessive ($bb$) individual?
What is the probability that a parent with a $BB$ genotype will produce a gamete carrying the $B$ allele?
What is the probability that a parent with a $BB$ genotype will produce a gamete carrying the $B$ allele?
In genetics, what is the term for the offspring resulting from a cross between two homozygous parents with different phenotypes?
In genetics, what is the term for the offspring resulting from a cross between two homozygous parents with different phenotypes?
What is always true of members of the F1 generation when complete dominance is exhibited?
What is always true of members of the F1 generation when complete dominance is exhibited?
If all offspring from a particular cross are heterozygous, what can be inferred about the genotypes of the parents?
If all offspring from a particular cross are heterozygous, what can be inferred about the genotypes of the parents?
What is the probability of each parent ($Bb$) producing a gamete carrying the $b$ allele?
What is the probability of each parent ($Bb$) producing a gamete carrying the $b$ allele?
The offspring resulting from a cross between two F1 generation individuals are referred to as the:
The offspring resulting from a cross between two F1 generation individuals are referred to as the:
In a cross between two heterozygous individuals ($Bb$), what is the probability that the offspring will also be heterozygous ($Bb$)?
In a cross between two heterozygous individuals ($Bb$), what is the probability that the offspring will also be heterozygous ($Bb$)?
In a cross between two heterozygous individuals ($Bb$), what is the probability of an offspring exhibiting the recessive phenotype?
In a cross between two heterozygous individuals ($Bb$), what is the probability of an offspring exhibiting the recessive phenotype?
Considering a simple Mendelian trait with complete dominance, what is the expected phenotypic ratio in the F2 generation resulting from a cross between two heterozygous individuals?
Considering a simple Mendelian trait with complete dominance, what is the expected phenotypic ratio in the F2 generation resulting from a cross between two heterozygous individuals?
Why is a cross between two heterozygous individuals not considered pure-breeding?
Why is a cross between two heterozygous individuals not considered pure-breeding?
In the context of genetic probability, what does a probability of 1 indicate?
In the context of genetic probability, what does a probability of 1 indicate?
Flashcards
Homozygous
Homozygous
Having two identical alleles for a trait (e.g., BB or bb).
Phenotype
Phenotype
The physical appearance of an organism based on its genotype.
Genotype
Genotype
The genetic makeup of an organism (e.g., BB, Bb, bb).
Gametes
Gametes
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Punnett Square
Punnett Square
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Probability in Genetics
Probability in Genetics
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F1 Generation
F1 Generation
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Dominant Allele
Dominant Allele
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Recessive Allele
Recessive Allele
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Heterozygous
Heterozygous
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Complete Dominance
Complete Dominance
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F2 Generation
F2 Generation
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Phenotypic Ratio
Phenotypic Ratio
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Pure-Breeding
Pure-Breeding
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Probability
Probability
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Study Notes
- A Punnett square predicts offspring genotypes and phenotypes from a cross.
- Gamete types from one parent are on the Punnett square's right side, while those from the other parent are at the top.
- Offspring genotypes and phenotypes are shown in the Punnett square's boxes.
Homozygous Parents with Black Fur
- Crossing two homozygous parents result in all gametes carry the B allele.
- All offspring from homozygous parents (BB) have the same genotype and phenotype as their parents (BB, black fur).
- The probability of black fur offspring is 1; the probability of white fur offspring is 0.
- Pure-breeding is breeding two homozygous individuals for a gene, resulting in homozygous offspring with the same genotype for the trait.
F1 Generation Cross
- The first filial generation (F1) results from crossing two homozygous individuals with different phenotypes, i.e dominant and recessive.
- The black fur allele (B) is dominant, and the white fur allele (b) is recessive.
- Gametes from a BB parent carry the B allele, and gametes from a bb parent carry the b allele.
- All offspring have a Bb genotype and black fur phenotype.
- F1 generation members are heterozygous and express the dominant phenotype with complete dominance.
Crosses Between Heterozygous Individuals
- The second filial generation (F2) comes from a cross between two F1 individuals or two heterozygous individuals with the dominant phenotype.
- Heterozygous parents produce B and b gametes, each with a probability of 0.5 (1/2).
- The probability of a Bb genotype 2 in 4 (0.5).
- The probability of a BB genotype is 1 in 4 (0.25).
- The probability of a bb genotype is 1 in 4 (0.25).
- The probability of black fur is 3 in 4 (0.75).
- The probability of white fur is 1 in 4 (0.25).
- The phenotypic ratio of black to white fur is 3:1.
- Heterozygous individuals with the same phenotype can produce offspring that are different and breeding between heterozygous individuals isn't pure-breeding.
Probability in Genetics
- A 3 in 4 chance of black fur doesn't guarantee 3 out of 4 offspring will have black fur.
- Probability and actual outcomes may differ unless the probability is 0 or 1.
- This is similar to a coin toss, where a 1 in 2 chance of heads or tails doesn't guarantee equal results in a few tosses.
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Description
Learn how to use a Punnett square to predict offspring genotypes and phenotypes from a cross. Explore how gamete types from each parent determine the genetic makeup of offspring. Understand homozygous crosses and the F1 generation.
