Genetics Quiz: Inheritance Patterns

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

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?

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?

Homozygote

Autosomal dominant (correct)

Compound heterozygote

Autosomal recessive

What is the probability of an affected child from an affected parent in autosomal dominant inheritance?

50% (B) Signup and view all the answers

Which of the following best defines homologous chromosomes?

Chromosomes that contain identical loci and pair during meiosis (B) Signup and view all the answers

What does the term 'penetrance' refer to in genetics?

The degree to which a phenotype is expressed (A) Signup and view all the answers

Which genotype represents a heterozygote?

AB (C) Signup and view all the answers

What is a compound heterozygote?

Two different mutant alleles at a gene locus (D) Signup and view all the answers

What does incomplete penetrance indicate in the context of autosomal dominant inheritance?

Some individuals with the genotype do not express the phenotype. (B) Signup and view all the answers

Which of the following is an example of autosomal recessive inheritance?

Cystic fibrosis (B) Signup and view all the answers

In X-linked dominant inheritance, which statement is true regarding affected males?

They can pass the condition to their daughters. (B) Signup and view all the answers

What is the typical risk of an affected child being born to carrier parents of an autosomal recessive disorder?

25% risk of an affected child (C) Signup and view all the answers

Variable expressivity in genetics refers to which of the following?

The same genotype can result in different phenotypes. (C) Signup and view all the answers

Which disease primarily exhibits X-linked recessive inheritance patterns?

Hemophilia (A) Signup and view all the answers

What characterizes the inheritance of X-linked recessive disorders in females?

They often require two mutant copies of the gene to express the condition. (D) Signup and view all the answers

What outcome is expected when a normal stature couple has a child with achondroplasia?

It is likely caused by a new mutation. (C) Signup and view all the answers

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.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on key concepts of genetics, including alleles, inheritance patterns, and penetrance. This quiz covers essential topics such as autosomal dominant and recessive inheritance, along with X-linked disorders. Perfect for students wanting to reinforce their understanding of genetic principles.