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How many copies of an allele need to be present for someone to have cystic fibrosis?
Both cystic fibrosis and sickle cell anemia are single mutation diseases - one mutation in a single gene is enough to cause the disease. However, for cystic fibrosis both alleles of the gene must be mutated for the disease to develop. For sickle cell anemia, only one allele can carry the mutation and some signs of the disorder will be present. Having two alleles with the mutation causes much more significant disease.
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What does it mean that CF is a recessive gene?
The phenotype associated with a recessive gene is only expressed when two copies of the gene are present. For example, if a person has both a recessive allele and a dominant allele for CF, the person does not have CF. The person only has CF if he/she has two copies of the recessive allele.
Is cystic fibrosis controlled by a dominant allele or by a recessive allele?
It is controlled by a recessive allele. The gene encodes a chloride ion channel that is required to make sweat, mucus and a few other things. One copy of the gene is sufficient to prevent cystic fibrosis, and it is only when both copies are defective that the person would have the disease and show symptoms.
What only contributes to the phenotype when 2 copies are present?
Recessive alleles only contribute to the phenotype when two copies are present. This means that both copies of the gene must carry the recessive allele in order for it to be expressed phenotypically. If only one copy is present, the dominant allele will be expressed instead.
True False Cystic fibrosis is caused by a mutation that is the dominant allele of a gene?
False. Cystic fibrosis is caused by a mutation in the CFTR gene, which is a recessive allele. An individual must inherit two copies of the mutated gene (one from each parent) to develop the condition.
What the 2 alleles are that control a specific characteristic?
The two alleles that control a specific characteristic are typically referred to as the dominant allele and the recessive allele. The dominant allele is expressed in the phenotype when present with a recessive allele, while the recessive allele is only expressed when two copies are present.
What is a dominant allele called dominant'?
A dominant allele is called dominant because its effects will be expressed in the phenotype when present in the genotype, regardless of whether the individual has one or two copies of the allele.
What does this tell you about the allele for white hair in horses?
The allele for white hair in horses is present in this individual, as evidenced by the white hair present. This individual likely carries two copies of the allele, as white coat color is typically a recessive trait in horses.
What is trait called that appear only when both alleles are present?
A trait that appears only when both alleles are present is called a recessive trait. In this case, the trait is masked when the dominant allele is present, but becomes visible when two copies of the recessive allele are inherited.
Is an allele that produces a trait in the heterozygous condition recessive?
No. A recessive allele will not be expressed phenotypically in the heterozygous state. A recessive allele can only be expressed phenotypically in the homozygous state.
Which traits oberved were dominant and recessive?
In genetics, dominant traits are those that are expressed when an individual has one or two copies of the dominant allele, while recessive traits are only expressed when an individual has two copies of the recessive allele and no dominant allele present. Dominant traits often mask recessive traits in heterozygous individuals.
What terms is a comparison between the number of copies of a particular allele and the number of copies of that a gene?
The comparison between the number of copies of a particular allele and the total number of copies of a gene is referred to as allele frequency. Allele frequency represents how common an allele is in a population, expressed as a proportion or percentage of the total gene copies for that gene. It is a key concept in population genetics, helping to understand genetic diversity and evolutionary dynamics within a population.
What is the form of a gene that is hidden or masked when any other form of that same gene is present?
The hidden or masked form of a gene is called recessive. Recessive genes are only expressed when an individual carries two copies of the recessive allele. When a dominant allele is present, it will be expressed instead of the recessive allele.
