Podcast
Questions and Answers
What is the primary cause of monogenic diseases?
What is the primary cause of monogenic diseases?
- Chromosomal abnormalities
- Multiple gene mutations
- Point mutations in single genes (correct)
- Environmental factors
Which of the following publications helped to catalog monogenic diseases?
Which of the following publications helped to catalog monogenic diseases?
- Principles of Genetics
- Mendelian Inheritance (correct)
- Genetic Disorders of the World
- The Human Genome Project
How many recognized monogenic diseases are attributed to mutations in known genes?
How many recognized monogenic diseases are attributed to mutations in known genes?
- 1200
- 2000
- 2800 (correct)
- 1777
What percentage of the genome is known to encode proteins?
What percentage of the genome is known to encode proteins?
What does it mean for a gene to be a 'modifier' in monogenic diseases?
What does it mean for a gene to be a 'modifier' in monogenic diseases?
Approximately how many genes are suspected to have a genetic basis but have unknown causative genes?
Approximately how many genes are suspected to have a genetic basis but have unknown causative genes?
Who was Victor McKusick?
Who was Victor McKusick?
What online resource was developed to manage an increasing number of described monogenic diseases?
What online resource was developed to manage an increasing number of described monogenic diseases?
What is indicated by the need to split the collection of monogenic diseases into more than two volumes?
What is indicated by the need to split the collection of monogenic diseases into more than two volumes?
What percentage of genes in the human genome is estimated to have a known function?
What percentage of genes in the human genome is estimated to have a known function?
What ratio of phenotypes is expected in the second filial generation from a dihybrid cross according to Mendel's experiments?
What ratio of phenotypes is expected in the second filial generation from a dihybrid cross according to Mendel's experiments?
In Mendel's law of independent assortment, what is true about the transmission of different gene pairs?
In Mendel's law of independent assortment, what is true about the transmission of different gene pairs?
What characterizes a backcross?
What characterizes a backcross?
What term is used for the position of a gene on a chromosome?
What term is used for the position of a gene on a chromosome?
How many alleles can exist for a single gene, as illustrated by the beta globin gene example?
How many alleles can exist for a single gene, as illustrated by the beta globin gene example?
Which of the following best describes monogenic diseases?
Which of the following best describes monogenic diseases?
What does the genotype 'S' in the beta globin gene represent?
What does the genotype 'S' in the beta globin gene represent?
What is indicated by phenotypic ratios in Mendel's experiments?
What is indicated by phenotypic ratios in Mendel's experiments?
What type of cross results in a 1:2:1 phenotypic ratio?
What type of cross results in a 1:2:1 phenotypic ratio?
Which of the following describes a dihybrid?
Which of the following describes a dihybrid?
What percentage of known hereditary diseases are associated with specific genes according to the provided information?
What percentage of known hereditary diseases are associated with specific genes according to the provided information?
Which plant species did Mendel choose for his experiments?
Which plant species did Mendel choose for his experiments?
What was the observed phenotypic ratio in the second filial generation (F2) according to Mendel’s experiments?
What was the observed phenotypic ratio in the second filial generation (F2) according to Mendel’s experiments?
Which concept states that members of a gene pair separate into different gametes?
Which concept states that members of a gene pair separate into different gametes?
What term did Mendel use to refer to what we now call genes?
What term did Mendel use to refer to what we now call genes?
In Mendel’s experiments, which phenotype dominated the first filial generation (F1)?
In Mendel’s experiments, which phenotype dominated the first filial generation (F1)?
What hypothesis suggests that different shapes of a phenotype correspond to different appearances of hereditary particles?
What hypothesis suggests that different shapes of a phenotype correspond to different appearances of hereditary particles?
Which of the following is NOT one of Mendel's five core hypotheses?
Which of the following is NOT one of Mendel's five core hypotheses?
What method did Mendel use to ensure he knew which parent was male and which was female?
What method did Mendel use to ensure he knew which parent was male and which was female?
How did Mendel ensure his parental lines were pure before beginning experiments?
How did Mendel ensure his parental lines were pure before beginning experiments?
What term describes individuals that carry two identical alleles at the same locus?
What term describes individuals that carry two identical alleles at the same locus?
Which genotype indicates someone is a carrier for sickle cell anemia?
Which genotype indicates someone is a carrier for sickle cell anemia?
Which of the following describes the phenotype?
Which of the following describes the phenotype?
What defines a proband in genetic analysis?
What defines a proband in genetic analysis?
What character trait is expressed in individuals with at least one copy of a defective gene?
What character trait is expressed in individuals with at least one copy of a defective gene?
In the context of sickle cell anemia, what does the term recessive imply?
In the context of sickle cell anemia, what does the term recessive imply?
What is a compound heterozygote?
What is a compound heterozygote?
Which blood group is an example of codominance?
Which blood group is an example of codominance?
What does the genotype for an individual with sickle cell anemia typically look like?
What does the genotype for an individual with sickle cell anemia typically look like?
What kind of individual is classified as a healthy carrier?
What kind of individual is classified as a healthy carrier?
Study Notes
Monogenic Diseases Overview
- Monogenic diseases are hereditary conditions caused by mutations in a single gene, generally point mutations.
- Pathogenesis in these diseases is primarily attributable to one mutated gene, although modifiers may involve other genes with minor effects.
- Only 1.4% of the human genome encodes proteins, approximately 22,000 genes identified.
Classification and Recognition of Monogenic Diseases
- Medical geneticist Victor McKusick initiated the collection of monogenic disease descriptions, leading to his publication "Mendelian Inheritance."
- Over time, this collection expanded significantly, necessitating online accessibility via OMIM (Online Mendelian Inheritance In Man).
- Around 2800 monogenic diseases are linked to mutations in known genes.
- An additional 1777 diseases have known gene loci, but unidentified causative genes.
- Nearly 2000 diseases have suspected genetic bases without knowledge of loci or genes.
Mendelian Genetics
- Gregor Mendel conducted foundational experiments with Pisum sativum (pea plants) in the 19th century identifying basic principles of inheritance.
- He established concepts such as inheritance patterns, dominant and recessive traits through systematic crossing of pea plants.
- Mendel's law of uniformity states that crossing two homozygotes results in a uniform F1 generation that is heterozygous.
- The law of segregation explains how gene pairs separate into gametes, creating predictable ratios in offspring.
- The law of independence states that different gene pairs assort independently during gamete formation.
Key Genetic Concepts
- Locus: The specific position of a gene on a chromosome.
- Alleles: Variants of a gene, such as normal beta globin and mutated versions associated with conditions like sickle cell anemia.
- Genotype: The genetic makeup of an individual; e.g., heterozygous (beta A, beta S) or homozygous (beta S, beta S).
- Phenotype: Observable traits influenced by genotype.
- Carrier: A healthy heterozygote who does not express symptoms but can pass on the recessive trait.
- Proband: The first affected individual in a genetic analysis, often denoted in family trees.
Types of Genetic Inheritance
- Dominant Inheritance: Expressed with just one faulty allele; causes phenotype in heterozygotes.
- Recessive Inheritance: Requires two copies of the defective gene to manifest the disease.
- Codominance: A heterozygous state expresses phenotypes distinct from both homozygous states, evident in blood types (e.g., AB blood group).
Summary of Mendel's Hypotheses
- Mendel proposed five main concepts on heredity:
- Existence of genes as hereditary particles.
- Genes appear in pairs as alleles.
- Gametes contain one allele from each gene pair.
- Equal proportions of alleles are distributed in gametes.
- Random fertilization occurs during zygote formation.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Explore the fundamentals of monogenic diseases in this quiz. Learn about the inheritance patterns and the role of point mutations in single-gene disorders. This lesson will provide a clear understanding of how these genetic conditions manifest and how they are categorized.
