Questions and Answers
What is the difference between a gene and an allele?
A gene is a stretch of DNA or RNA that determines a certain trait, while an allele is one of the alternative forms of a gene.
What is the difference between phenotype and genotype?
Genotype is the genetic makeup of an organism, while phenotype is the physical characteristics.
What is the difference between a dominant and a recessive allele?
A dominant allele masks the expression of an alternative gene and appears in the heterozygous condition, while a recessive allele is masked by the dominant allele and appears only in homozygous condition.
Who was Gregor Mendel and why is he famous?
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What were Mendel's experiments and what data did he collect from them?
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Why did Mendel select pea plants for his experiments?
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What do the terms heterozygous and homozygous mean?
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Why do we have to specify 'dominant' or 'recessive' with homozygous but not heterozygous?
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What is a Punnett Square?
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What is a monohybrid cross?
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What do we mean by 'complex' inheritance or 'non-Mendelian' inheritance?
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What is the law of independent assortment?
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What is the Law of Segregation?
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What is the rule of dominance?
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What is the difference between codominant and incomplete dominant inheritance?
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What is X-linked inheritance?
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A dominant allele/trait is one that always shows up more often in a population.
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An allele is the same as a gene, but merely a different version of the gene.
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A genotype is the physical expression of the DNA an organism shows.
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Genetics is the branch of biology that involves the study of how different traits are transmitted from one generation to the next.
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For F = furry and f = non-furry; a homozygous dominant and a homozygous recessive parent will always have furry children.
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Punnett Squares show that it only takes having 4 offspring to come up with all possible combinations of alleles.
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The law of independent assortment states that ALL traits are inherited separately from one another.
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What is a stretch of DNA that determines a certain trait?
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The _________ is the physical expression of traits.
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When an organism has two different alleles for the same gene, it is called:
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Parents that breed and are the same except for one trait would create a:
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Which of the following is an example of a homozygous recessive individual?
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Which of the following is an example of a heterozygous individual?
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For cats, B = black fur and b = white fur. A heterozygous parent mates with a homozygous recessive parent. What are the odds that their kitten is a heterozygote?
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For B = black fur and b = white fur: Cross BB with Bb; what is the accurate phenotype ratio?
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A blue fish mates with a red fish and creates a purple-colored offspring. In these fish, color is inherited in what way?
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What do the letters on the inside of a Punnett Square represent?
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The specific location of a gene/DNA sequence is called a(n)?
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The study of heredity is called:
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Who is the father of genetics?
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Gregor Mendel concluded that traits are:
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Hair color and eye color are examples of a person's:
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The principles of probability can be used to:
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A couple has 2 children, both of whom are boys. What is the chance that the parent's next child will be a boy?
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Genes located on homologous chromosomes may have alternate forms that control different forms of a trait. These alternate forms of a gene are called:
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If an individual possesses two recessive alleles for the same trait, the individual is said to be:
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If a pea plant were homozygous recessive for height, how would its alleles be represented?
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When an organism has two alleles for a particular trait that are different, the organism is called:
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A genetic trait that appears in every generation of offspring is called:
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The term for a cross that involves just one trait, such as pod shape, is called:
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When Gregor Mendel crossed homozygous purple-flowered plants with homozygous white-flowered plants, all the offspring were purple because:
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In Mendel's garden pea experiment, he allowed each variety of garden pea to self-pollinate for several generations to produce the original parents or:
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When Gregor Mendel crossed a homozygous tall plant with a homozygous short plant, the F1 plants inherited:
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Mendel's law of segregation states that:
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The phenotype of an organism is:
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A dog's phenotype can be determined by:
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Which of the following describes an organism that has the phenotype Bb?
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An individual heterozygous for a trait and an individual homozygous recessive for the trait are crossed and produce many offspring. These offspring are likely to be:
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Tallness (T) is dominant over shortness (t) in pea plants. Which of the following represents the genotype of a pea plant that is heterozygous for tallness?
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Mendel's finding that the inheritance of one trait had no effect on the inheritance of another became known as the:
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A useful device for predicting the possible offspring of crosses between different genotypes is the:
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The _______ produced by each parent are shown along the sides of a Punnett square.
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What do the letters inside the grid of the Punnett square represent?
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A female guinea pig homozygous dominant for black fur color is mated with a male homozygous for white fur color. In a litter of eight offspring, there would probably be:
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In mink, brown fur color is dominant to silver-blue fur color. If a homozygous brown mink is mated with a silver-blue mink and 8 offspring are produced, how many would be expected to be silver-blue?
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The unknown genotype of an individual with a dominant phenotype can be determined using:
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If a characteristic is sex-linked, it occurs only in females or males.
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Since the allele for colorblindness is located on the X chromosome, colorblindness is sex-linked.
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Which of the following describes hemophilia?
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Study Notes
Genetics Terminology
- Gene: A segment of DNA or RNA that determines a specific trait; can have multiple forms known as alleles.
- Allele: Alternative forms of a gene; for instance, eye color has several alleles (e.g., blue or brown).
- Genotype: The genetic composition of an organism, while phenotype refers to its observable physical characteristics.
Dominance and Inheritance
- Dominant Allele: Masks the expression of a recessive allele; shows in both homozygous and heterozygous conditions.
- Recessive Allele: Only expressed in homozygous conditions; masked by dominant alleles.
- Heterozygous: An organism with two different alleles for the same gene.
- Homozygous: An organism with identical alleles for a specific gene.
Mendel’s Contributions
- Gregor Mendel: Conducted experiments with pea plants, establishing foundational principles of heredity, such as dominance and segregation.
- Mendel’s Laws: Include the Law of Segregation (two alleles for a trait separate during gamete formation) and the Law of Independent Assortment (genes segregate independently).
Punnett Squares and Genetic Crosses
- Punnett Square: A tool for predicting offspring traits based on parental genotypes, indicating possible combinations of alleles.
- Monohybrid Cross: Involves one trait; contrasts one characteristic between two organisms.
- Dihybrid Cross: Involves two traits; compares two characteristics simultaneously.
Patterns of Inheritance
- Codominance: Both alleles in a heterozygous individual contribute equally to the phenotype (e.g., a blue fish crossed with a red fish produces purple offspring).
- Incomplete Dominance: Neither allele is dominant, resulting in a blended phenotype.
X-linked Inheritance
- X-linked Traits: Traits controlled by genes located on the X chromosome; can manifest differently in males and females, crucial for identifying inheritance patterns.
Genetic Probability
- Probability: The principles of probability apply to predict the likelihood of traits in offspring based on their genotypes.
- Phenotypic Ratios: The expected proportion of different phenotypes in offspring based on genetic crosses.
Special Traits
- Sex-Linked Traits: Such as colorblindness and hemophilia, which occur due to alleles on the sex chromosomes and often show different patterns in males and females.
- Test Cross: A method used to determine the genotype of an organism with a dominant phenotype by crossing it with a homozygous recessive individual.
Key Genotypes and Phenotypes
- Homozygous Recessive Example: Represented as "aa."
- Heterozygous Example: Represented as "AB" or "Tt" for tallness.
- Genetic Outcome Example: A cross between a heterozygous parent and a homozygous recessive parent results in a variety of offspring phenotypes.
Importance of Genetics
- Genetics: The study of heredity and how traits are passed from parents to offspring, influencing biodiversity and inheritance patterns in populations.
Studying That Suits You
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Description
Test your knowledge with these flashcards from Unit 8 of your science curriculum. This quiz covers essential genetic concepts such as genes, alleles, phenotypes, and genotypes. Perfect for reviewing before a test or reinforcing your understanding of genetics.
