Podcast
Questions and Answers
What defines an allele?
What defines an allele?
- A genetic constitution of an individual
- Observable physical manifestations of a genotype
- A pair of chromosomes during meiosis
- Alternative forms of a gene at the same locus (correct)
How does autosomal dominant inheritance affect generations?
How does autosomal dominant inheritance affect generations?
- Affected individuals are usually homozygotes
- It only affects males
- It skips generations frequently
- Affected individuals usually have affected parents (correct)
In which inheritance pattern is one mutated copy of a gene sufficient to cause a condition?
In which inheritance pattern is one mutated copy of a gene sufficient to cause a condition?
- Homozygote
- Autosomal dominant (correct)
- Compound heterozygote
- Autosomal recessive
What is the probability of an affected child from an affected parent in autosomal dominant inheritance?
What is the probability of an affected child from an affected parent in autosomal dominant inheritance?
Which of the following best defines homologous chromosomes?
Which of the following best defines homologous chromosomes?
What does the term 'penetrance' refer to in genetics?
What does the term 'penetrance' refer to in genetics?
Which genotype represents a heterozygote?
Which genotype represents a heterozygote?
What is a compound heterozygote?
What is a compound heterozygote?
What does incomplete penetrance indicate in the context of autosomal dominant inheritance?
What does incomplete penetrance indicate in the context of autosomal dominant inheritance?
Which of the following is an example of autosomal recessive inheritance?
Which of the following is an example of autosomal recessive inheritance?
In X-linked dominant inheritance, which statement is true regarding affected males?
In X-linked dominant inheritance, which statement is true regarding affected males?
What is the typical risk of an affected child being born to carrier parents of an autosomal recessive disorder?
What is the typical risk of an affected child being born to carrier parents of an autosomal recessive disorder?
Variable expressivity in genetics refers to which of the following?
Variable expressivity in genetics refers to which of the following?
Which disease primarily exhibits X-linked recessive inheritance patterns?
Which disease primarily exhibits X-linked recessive inheritance patterns?
What characterizes the inheritance of X-linked recessive disorders in females?
What characterizes the inheritance of X-linked recessive disorders in females?
What outcome is expected when a normal stature couple has a child with achondroplasia?
What outcome is expected when a normal stature couple has a child with achondroplasia?
Flashcards
Allele
Allele
Alternative forms of a gene found at the same location on homologous chromosomes.
Pedigree
Pedigree
A diagram showing family relationships and the occurrence of a specific trait over generations.
Autosomal Dominant Inheritance
Autosomal Dominant Inheritance
Inheritance patterns where a single mutated gene is sufficient to cause a condition.
Homozygote
Homozygote
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Heterozygote
Heterozygote
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Phenotype
Phenotype
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Genotype
Genotype
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Homologous Chromosomes
Homologous Chromosomes
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Penetrance
Penetrance
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Variable Expressivity
Variable Expressivity
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De Novo Mutation
De Novo Mutation
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Autosomal Recessive Inheritance
Autosomal Recessive Inheritance
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X-Linked Recessive Inheritance
X-Linked Recessive Inheritance
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X-Linked Dominant Inheritance
X-Linked Dominant Inheritance
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Autosomal Inheritance
Autosomal Inheritance
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Study Notes
Course Information
- Faculty of Medicine, Gala University
- Fall 2024
- Course: BMS141, Lecture #3 Genetics
- Topic: Mendelian Inheritance
Learning Outcomes
- Recall key genetic terms
- Understand and compare characteristics of autosomal, sex-linked, dominant, and recessive inheritance patterns.
- Calculate probabilities of genotypic and phenotypic outcomes based on parental genotypes and inheritance modes.
- Define penetrance and expressivity.
Genetic Terms
- Allele: Alternative forms of a gene located at the same locus on homologous chromosomes.
- Dominant/Recessive: Alleles that affect the phenotype.
- Homologous chromosome: Chromosome pairs during meiosis that contain identical loci.
- Genotype: The genetic makeup of an individual.
- Phenotype: Observable physical characteristics resulting from the genotype.
- Homozygote: Genotype with two identical alleles for a gene (can be normal or abnormal).
- Heterozygote: Genotype with two different alleles for a gene.
- Compound heterozygote: Two different mutant alleles at the same gene locus.
- Pedigree: A diagram showing family history, relationships, and occurrence of a hereditary condition.
Modes of Inheritance
-
Mendelian (Traditional): Inheritance patterns based on chromosomes.
-
Autosomal Dominant (AD): One mutated gene copy is enough to cause the condition, appearing in each generation. Males and females affected equally, with male-to-male transmission possibility. Affected individuals have a 50% chance of passing the condition to their offspring.
- Examples: Achondroplasia, Marfan syndrome, Osteogenesis imperfecta.
- Concepts: Penetrance (proportion of affected individuals with the same genotype), Complete penetrance (100% expression), Incomplete/Reduced penetrance (not all individuals expressing the phenotype). Variable Expressivity (condition severity varies). New mutations.
-
Autosomal Recessive (AR): Two mutated gene copies are needed for the condition (homozygous). Males and females affected equally. Parents are unaffected carriers. Risk of having an affected child is 25%, a carrier child 50%, and normal child 25% with an affected carrier pregnancy.
- Examples: B thalassemia, Cystic fibrosis.
-
X-Linked Dominant (XLD): Both males and females express the disease state. Affected males cannot pass the condition to sons but all daughters will. Affected females have a 50% chance of passing the condition in each pregnancy to male or female children.
- Examples: X-linked hypophosphatemic rickets.
-
X-Linked Recessive (XLR): Affected is expressed in males but not usually expressed or rarely expressed in females. One mutant gene copy manifests in males. Males cannot pass on to male children. All daughters of affected males will be carriers. A carrier woman has a 50% chance of having an affected son and a 50% chance of having a carrier daughter.
- Examples: Duchenne muscular dystrophy.
-
Y-Linked: Only males affected. Passed from males to their male children.
Additional Notes
- Diagrams and images are provided as part of the presentation.
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