Podcast
Questions and Answers
In a scenario where a disease is caused by a dominant negative mutation, what is the most likely outcome if a cell contains both the mutated gene and several copies of the functional gene?
In a scenario where a disease is caused by a dominant negative mutation, what is the most likely outcome if a cell contains both the mutated gene and several copies of the functional gene?
- The functional gene copies compensate for the mutated gene, resulting in a normal phenotype.
- The mutated gene interferes with the functional genes, leading to a disease phenotype. (correct)
- The cell selectively expresses the functional genes, ignoring the mutated gene.
- The cell undergoes apoptosis due to the presence of the mutated gene.
Considering the concept of anticipation in trinucleotide repeat disorders, which of the following scenarios is most likely to be observed across generations?
Considering the concept of anticipation in trinucleotide repeat disorders, which of the following scenarios is most likely to be observed across generations?
- A consistent age of onset and severity of symptoms across all generations.
- A later age of onset and milder symptoms in subsequent generations.
- A random distribution of age of onset and symptom severity, unrelated to parental phenotypes.
- An earlier age of onset and more severe symptoms in subsequent generations. (correct)
In the context of sex-influenced traits, if a particular autosomal gene variant is associated with a specific phenotype that is more commonly observed in males than in females, which mechanism is most likely at play?
In the context of sex-influenced traits, if a particular autosomal gene variant is associated with a specific phenotype that is more commonly observed in males than in females, which mechanism is most likely at play?
- The gene is located on the Y chromosome, leading to its expression only in males.
- The gene is subject to genomic imprinting, with expression occurring only from the paternally inherited allele.
- Hormonal differences between males and females affect the expression of the gene. (correct)
- The gene undergoes epigenetic modification specifically in females, silencing its expression.
If a researcher observes a novel genetic mutation where individuals with the same genotype exhibit a wide range of phenotypic expressions, from mild to severe, even within the same family, which genetic principle is most likely responsible for this observation?
If a researcher observes a novel genetic mutation where individuals with the same genotype exhibit a wide range of phenotypic expressions, from mild to severe, even within the same family, which genetic principle is most likely responsible for this observation?
Considering a scenario where gene A influences hair color and gene B independently affects the expression of gene A, what genetic phenomenon is being exemplified?
Considering a scenario where gene A influences hair color and gene B independently affects the expression of gene A, what genetic phenomenon is being exemplified?
If a geneticist discovers that a single gene mutation leads to multiple, seemingly unrelated symptoms affecting different organ systems, what genetic principle is most likely at play?
If a geneticist discovers that a single gene mutation leads to multiple, seemingly unrelated symptoms affecting different organ systems, what genetic principle is most likely at play?
Suppose a genetic test reveals that an individual carries a genotype known to cause a specific disease with 70% penetrance. What does this percentage most accurately indicate?
Suppose a genetic test reveals that an individual carries a genotype known to cause a specific disease with 70% penetrance. What does this percentage most accurately indicate?
In a scenario where an individual is heterozygous for two co-dominant alleles, each coding for a distinct protein product, what would be the expected phenotypic expression?
In a scenario where an individual is heterozygous for two co-dominant alleles, each coding for a distinct protein product, what would be the expected phenotypic expression?
An individual with blood type AB marries an individual with blood type O. What are the possible blood types of their offspring, considering the co-dominance of A and B alleles?
An individual with blood type AB marries an individual with blood type O. What are the possible blood types of their offspring, considering the co-dominance of A and B alleles?
In the context of autosomal recessive diseases, what is the probability that a child will inherit the disease if both parents are known carriers?
In the context of autosomal recessive diseases, what is the probability that a child will inherit the disease if both parents are known carriers?
Flashcards
Dominant Genes
Dominant Genes
Alleles that require only one copy to express the associated phenotype.
Co-dominance
Co-dominance
When two alleles are both expressed equally, resulting in a phenotype that shows both traits.
Dominant Negative Disorder
Dominant Negative Disorder
A mutation that causes a dysfunctional gene product, interfering with the function of the normal protein.
Haploinsufficiency
Haploinsufficiency
Signup and view all the flashcards
Penetrance
Penetrance
Signup and view all the flashcards
Somatic Instability
Somatic Instability
Signup and view all the flashcards
Anticipation
Anticipation
Signup and view all the flashcards
Sex-Influenced Traits
Sex-Influenced Traits
Signup and view all the flashcards
Epistasis
Epistasis
Signup and view all the flashcards
Pleiotropy
Pleiotropy
Signup and view all the flashcards
Study Notes
Dominant vs. Recessive Genes
- Dominant genes need only one copy to express the phenotype.
- Recessive genes need two copies to express the phenotype.
- The Rh factor in blood is an example; RH+ is dominant, while RH- is recessive.
- Genotypes for Rh factor can be homozygous Rh+, heterozygous, or homozygous Rh-.
- Phenotypes will be Rh positive for homozygous Rh+ and heterozygous individuals.
- Phenotypes will be Rh negative for homozygous Rh- individuals.
Co-dominance vs. Classic Dominance
- Co-dominance occurs when two alleles are both expressed equally.
- In classic dominance, one allele completely dominates over the other.
- Blood type AB is an example of co-dominance; both A and B proteins are expressed.
- Blood type A (genotype AO or AA) and blood type B (genotype BO or BB) are examples of classic dominance.
Dominant Inheritance Patterns
- Dominant negative disorders: A mutation in one allele causes a dysfunctional gene product, and even one functional allele cannot compensate.
- Huntington's disease and some p53 tumor suppressor gene mutations are examples.
- Haploinsufficiency: One functional allele is insufficient to maintain normal function, leading to disease.
- Ehlers-Danlos syndrome is an example of haploinsufficiency.
Carrier Status
- Carriers of a recessive allele have one normal and one mutated allele.
- Carriers do not express the disease phenotype but can pass on the mutated allele.
- In autosomal recessive diseases, like cystic fibrosis, an individual with a Cc genotype is a carrier.
Incomplete Dominance
- In incomplete dominance, neither allele is completely dominant, and the heterozygote shows a blended phenotype.
- Snapdragon flowers, where RR (red) and WW (white) produce RW (pink) offspring, exemplify incomplete dominance.
- Eye and hair color in humans can exhibit incomplete dominance.
Penetrance
- Penetrance: The proportion of individuals with a specific genotype that express the associated phenotype.
- Complete penetrance is when everyone with the genotype develops the disease phenotype.
- An example is Achondroplasia (dwarfism).
- Incomplete penetrance: Some individuals with the disease-causing genotype may not express the disease phenotype.
- An example is hereditary breast cancer (BRCA1 mutation).
Variable Expressivity
- Variable expressivity: Individuals with the same genotype express the same disease, but the severity or symptoms vary.
- Marfan syndrome is an example of variable expressivity, where symptoms range from mild to severe.
Trinucleotide Repeat Disorders
- Trinucleotide repeat disorders are caused by the expansion of a three-nucleotide sequence within a gene.
- Examples include Huntington’s disease and Fragile X syndrome.
- The repeats expand in size over generations, causing earlier onset and more severe symptoms (anticipation).
Somatic Instability and Anticipation
- Somatic instability: The expansion of trinucleotide repeats occurs in somatic cells, exacerbating the disease.
- Anticipation: Offspring of affected individuals experience symptoms earlier due to increased repeat number.
Sex-Influenced and Sex-Limited Traits
- Sex-influenced traits: Autosomal genes where expression of the trait is influenced by the sex of the individual.
- Male pattern baldness is an example, where the allele is dominant in males but recessive in females.
- Sex-limited traits: Found on autosomes but expressed only in one sex.
- Horns in sheep are an example where only males develop them.
Epistasis
- Epistasis: A gene interaction where one gene can mask the expression of another gene.
- Eye color is influenced by multiple genes.
Pleiotropy
- Pleiotropy: A single gene or variant affects multiple unrelated traits or systems.
- Marfan syndrome, caused by a mutation in the fibrillin gene, leads to various symptoms, including skeletal deformities and cardiovascular problems.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
