Podcast
Questions and Answers
What is required for a recessive gene to be expressed in an individual?
What is required for a recessive gene to be expressed in an individual?
- Any allele present in the individual
- A combination of dominant and recessive alleles
- Two recessive alleles (correct)
- At least one dominant gene
If both parents are heterozygous for a single-gene disorder, what is the probability of their child inheriting the disorder?
If both parents are heterozygous for a single-gene disorder, what is the probability of their child inheriting the disorder?
- 50%
- 0%
- 25% (correct)
- 75%
How does the probability of inheriting a recessive disease change if one parent has two recessive alleles?
How does the probability of inheriting a recessive disease change if one parent has two recessive alleles?
- The probability remains at 25%
- The probability decreases to 0%
- The probability increases to 50%
- The probability increases to 75% (correct)
Which of the following conditions is NOT classified as a single-gene disorder?
Which of the following conditions is NOT classified as a single-gene disorder?
What characteristic is commonly seen in mutated genes responsible for single-gene disorders?
What characteristic is commonly seen in mutated genes responsible for single-gene disorders?
Flashcards
Recessive gene expression
Recessive gene expression
A recessive gene is expressed only when both copies of the gene are mutated.
Heterozygous parents
Heterozygous parents
Both parents carry one copy of the mutated gene and one normal gene.
Probability for children inheriting disease (heterozygous parents)
Probability for children inheriting disease (heterozygous parents)
25% chance of inheriting the disease.
Single Parent with two recessive alleles
Single Parent with two recessive alleles
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Probability of inheriting disease (one homozygous recessive parent)
Probability of inheriting disease (one homozygous recessive parent)
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Study Notes
Single-Gene Disorders
- Single-gene disorders arise from a mutation in a single gene.
- Scientists have identified up to 4,000 single-gene disorders.
- Mutated genes are typically recessive.
- Recessive genes are masked by dominant genes.
Recessive Gene Expression
- For a recessive gene to be expressed, an individual must inherit two copies of the recessive allele, one from each parent.
Probability of Inheritance (Heterozygous Parents)
- If both parents are heterozygous for a recessive disease, the probability of a child inheriting the disease is 25%.
Probability with One Recessive Parent
- If one parent carries two recessive alleles, the probability of a child inheriting the disease increases significantly.
Examples of Single-Gene Disorders
- Sickle-cell anemia
- Cystic fibrosis
- Color blindness
- Hemophilia
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Description
Test your knowledge on single-gene disorders, including their characteristics, inheritance patterns, and examples. Learn about the probability of inheritance, particularly focusing on recessive genes and their expression in individuals. This quiz covers key concepts essential for understanding human genetics.
