Questions and Answers
What is the term for the pattern where a dominant allele is present but its effect is not visible?
In a case of incomplete dominance, what is the phenotype of the heterozygous offspring?
What is the term for the situation where the heterozygote has a more beneficial trait than either homozygote?
What is the reason for penetrance, according to the molecular perspective?
Signup and view all the answers
What is the term for the pattern where the heterozygote expresses both alleles simultaneously without forming an intermediate phenotype?
Signup and view all the answers
Why may heterozygotes have increased resistance to infection by microorganisms?
Signup and view all the answers
What is the result of a cross between homozygous red-flowered and homozygous white-flowered parents, in terms of flower color?
Signup and view all the answers
In dominant and recessive alleles, what is the main difference between the dominant and recessive alleles?
Signup and view all the answers
What is a characteristic of simple Mendelian inheritance?
Signup and view all the answers
What is the main goal of examining different patterns of Mendelian inheritance?
Signup and view all the answers
What is the term applied to the inheritance of alleles that obey Mendel's laws and follow a strict dominant/recessive relationship?
Signup and view all the answers
What can occur when a single gene has three or more alleles?
Signup and view all the answers
What is the result of a single copy of a dominant allele in a heterozygote?
Signup and view all the answers
What is an example of a complex inheritance pattern?
Signup and view all the answers
What is the relationship between genetic polymorphism and Mendelian inheritance?
Signup and view all the answers
What is the result of a mutation in a gene?
Signup and view all the answers
What is the blood type of an individual carrying the A and B alleles?
Signup and view all the answers
In X-linked inheritance, what percentage of the protein produced by a single copy of the dominant allele is sufficient to produce the dominant trait in a heterozygous female?
Signup and view all the answers
What type of inheritance pattern involves the effect of sex on the phenotype of the individual?
Signup and view all the answers
Which type of inheritance pattern involves traits that occur in only one of the two sexes?
Signup and view all the answers
What is the main difference between sex-influenced and sex-limited inheritance patterns?
Signup and view all the answers
In X-linked inheritance, what is the expression of the copy of the gene that males carry?
Signup and view all the answers
What is an example of codominance?
Signup and view all the answers
What regulates the molecular expression of genes in sex-influenced and sex-limited inheritance patterns?
Signup and view all the answers
Study Notes
Inheritance Patterns
- Incomplete Penetrance: A dominant allele is present, but its effects are not seen due to environmental influences or counteracting proteins from other genes.
Incomplete Dominance
- A heterozygote has a phenotype that is intermediate between the two corresponding homozygotes, e.g., a cross between red-flowered and white-flowered parents produces pink-flowered offspring.
Overdominance
- A heterozygote has a trait that is more beneficial than either homozygote.
- Three ways heterozygotes gain benefits:
- Increased resistance to infection by microorganisms
- Producing more forms of protein dimers with enhanced function
- Producing proteins that function under a wider range of conditions
Extensions of Mendelian Inheritance
- Mendelian inheritance describes patterns that obey two laws: the Law of Segregation and the Law of Independent Assortment.
- Simple Mendelian inheritance involves a single gene with two different alleles that display a simple dominant/recessive relationship.
Codominance
- The codominant alleles encode proteins that function slightly differently from each other, and the function of each protein in the heterozygote affects the phenotype uniquely.
- Example: blood typing, where an individual carrying the A and B alleles will have an AB blood type.
X-linked Inheritance
- Inheritance of genes located on the X chromosome.
- In mammals and fruit flies, males have one copy of X-linked genes, whereas females have two copies.
- If a pair of X-linked alleles shows a simple dominant/recessive relationship, 50% of the protein produced by a single copy of the dominant allele in a heterozygous female is sufficient to produce the dominant trait.
Sex-influenced Inheritance
- The effect of sex on the phenotype of an individual.
- Some alleles are recessive in one sex and dominant in the opposite sex.
- Sex hormones may regulate the molecular expression of genes, influencing the phenotypic effects of alleles.
Sex-limited Inheritance
- Traits that occur in only one of the two sexes.
- Example: breast development in mammals.
- Sex hormones that are primarily produced in only one sex are essential to produce a particular phenotype.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Understanding inheritance patterns, including incomplete penetrance and how environmental influences affect gene expression.